ISBN 978-4-908553-67-7

Guideline of Ocean Observations
Volumes 1 -10
Fourth Edition

The Oceanographic Society of Japan
April 2020

This page left intentionally blank.

Foreword for the 4th edition
In recent years, climate change has emerged with serious consequences in many regionsof the world.

Materials released into the ocean by human activities are diversifying, andthe abundance in the ocean continues to increase.

In such a changing marine

environment, technological innovations in oceanographic observation are progressing
rapidly.

On the other hand, it is required to share these technologies properly in thecommunity and provide data that guarantees traceability and comparability.

It is alsoessential to hand down these technologies and the basic knowledges to theoceanographers of the next generation.
The Oceanographic Society of Japan (JOS) has established an editorial committee for
Guideline of Ocean Observations to capture the latest trends in ocean observation andprovide the community with state-of-the-art guidelines.

JOS decided to make thisguideline both in Japanese and English, so that not only ocean scientists in Japan but inother countries can share those knowledges.
The first edition of Guideline of Ocean Observations was published in September 2015
with an overview of oceanographic observations and the latest oceanographic andanalytical methods.

After that, two revisions were made, and by April 2018, a total of

10 volumes and 40-chapter guidelines were arranged.
In this 4th edition, 12 chapters are newly added, and the contents of almost all chapters
are satisfied.

In addition, two chapters have been updated in this edition.

For thisguidelines, 44 authors working on a broad area of oceanography are involved in thewriting.
We hope that these guidelines will be used by many researchers around the world andcontribute to the advancement of oceanography.

Editor in chief for 4th edition
Guideline of Ocean Observations
Shigeyoshi Otosaka

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Foreword for the 3rd edition
Under the academic/social needs to cope with global environmental problem such as
climate changes and ocean acidification, technical innovation on ocean observations
have been progressed rapidly in recent years. Progresses are also ongoing in the fieldof world-wide organization of ocean observation by using common observation
procedures and standard/reference materials because it is obviously vital to publish datathat guarantees traceability and comparability with appropriate reference materials or
certified reference materials and that is clear about its uncertainties. Aiming to catchup such year-to-year progress in the ocean observations field, and to provide
state-of-the-art guideline of ocean observations to the communities, the Oceanographic
Society of Japan (JOS) has established the editorial committee of Guideline of Ocean
Observations in 2015, and published the Guideline of Ocean Observations describing
the most up-to-date oceanographic observation methods and analytical techniques. The
first edition of this Guideline of Ocean Observations were published in September
2015.
In the 2nd edition, several improvements had made in the table-of-contents page,reflecting the addition of authors and reviewers in some chapters. Some descriptions
regarding sea ice observations (Vol.7, Chap.5) had updated reflecting the changes interminology of sea ice by WMO Sea-Ice Nomenclature (2014). Also, link address of“Guide to best practice for ocean CO2 measurements” in Vol.3 had changed from
Carbon Dioxide Information Analysis Center (CDIAC) to the Ocean Carbon Data
System located within the NOAA National Centers for Environmental Information(NOAA-OCADS). Several chapters in sediment observation (Vol.5) andnatural/artificial radioactivity (Vol.9) are also added.
In this 3rd edition, several improvements had also made in the table-of-contents page,reflecting the addition of authors and reviewers in some chapters. We hope that theseguidelines will be used by many researchers worldwide and will contribute to theadvance of oceanography.
Thereafter this Guideline in English version will be renewed under the review of theeditorial committee, updating description corresponding to technical progresses as wellas adding new observation items if necessary.
Editor in chief for 3rd edition
Guideline of Ocean Observations
Tsuneo Ono

This page left intentionally blank.

Foreword for the 2nd edition
Under the academic/social needs to cope with global environmental problem such as
climate changes and ocean acidification, technical innovation on ocean observations
have been progressed rapidly in recent years. Progresses are also ongoing in the fieldof world-wide organization of ocean observation by using common observation
procedures and standard/reference materials because it is obviously vital to publish datathat guarantees traceability and comparability with appropriate reference materials or
certified reference materials and that is clear about its uncertainties. Aiming to catchup such year-to-year progress in the ocean observations field, and to provide
state-of-the-art guideline of ocean observations to the communities, the Oceanographic
Society of Japan (JOS) has established the editorial committee of Guideline of Ocean
Observations in 2015, and published the Guideline of Ocean Observations describing
the most up-to-date oceanographic observation methods and analytical techniques. The
first edition of this Guideline of Ocean Observations was published in December 2016.
Thereafter this Guideline is renewed every year under the review of the editorialcommittee, updating description corresponding to technical progresses as well as adding
new observation items if necessary.

In this 2nd edition, some descriptions regarding sea ice observations (Vol.7, Chap.5)
had updated reflecting the changes in terminology of sea ice by WMO
Sea-Ice Nomenclature (2014). Also, link address of “Guide to best practice forocean CO2 measurements” in Vol.3 had changed from CDIAC to NOAA-OCADS.
Several chapters in Sediment Analysis (Vol.5) and Natural and artificial radioactivity(Vol.9) are added as well as other small additions.
We hope that these guidelines will be used by many researchers worldwide and willcontribute to the advance of oceanography.

Editor in chief for 2nd edition
Guideline of Ocean Observations
Tsuneo Ono

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Foreword
Measures to mitigate and adapt to climate change are urgently needed; the importanceof understanding the state of climate change in the oceans is rising. In monitoring
environmental changes at the global scale, it is obviously vital to publish data thatguarantees traceability and comparability with appropriate reference materials or
certified reference materials and that is clear about its uncertainties.
In recent years we have been building our knowledge of changes within the oceans
through international cooperation and collaboration, for example, by re-occupation ofWorld Ocean Circulation Experiment (WOCE); our findings were cited in the Fifth
Assessment Report from the IPCC. To implement plans to make all measurement values
used in climate change research completely SI-traceable, the General Conference on
Weights and Measures has been providing advice to relevant institutions. Throughmeasures such as promulgating the use of standard materials for nutrients, we aremaking progress in comparability of data, research that depends on this comparability,
and R&D on standard materials.
However, the guidelines used for measurement and analysis do not seem to be
keeping up with this progress. The Oceanographic Observation Guidelines published by
the Japan Meteorological Agency in 1999 are relatively widely used in Japan, but theircontent is not always completely up-to-date and the Guidelines are now quite hard to
obtain. In 2010, the WOCE Manual was revised and published as the GO-SHIP
Oceanographic Observation Manual (IOCCP Report No.14, 2010), but this isprincipally for repeat hydrography in the open ocean; it was not intended to guide awide range of users. There are a number of other manuals and guidelines available but
some of them are only written in Japanese, whereas others are only written in English;
moreover, they mix together up-to-date content and less up-to-date content.
In this context, the Oceanographic Society of Japan (JOS) has decided to set up an
editorial committee for oceanographic observation guidelines, to review and collate thevarious existing guidelines, and to incorporate necessary revisions and fill in any gaps.
We will publish Oceanographic Observation Guidelines describing the most up-to-dateoceanographic observation methods and analytical techniques, and we will make these
new guidelines available through the JOS website.
We intend to continuously update these guidelines so that the most up-to-date
methods are always accessible. We hope that these guidelines will be used by many
researchers worldwide and will contribute to the advance of oceanography.
Editor in chief
Oceanographic observation guidelines
Takeshi Kawano

List of the authors at the time of writing
Michio AOYAMA

Takafumi ARAMAKI
Sanae CHIBA
Fuminori HASHIHAMA
Kazuhiko HAYASHI
Masao ISHII
Hideki KAERIYAMA
Kenichi KATAYAMA
Takeshi KAWANO
Hiroshi KOBAYASHI
Shigeaki KOJIMA
Naohiro KOSUGI
Shinya KOUKETSU
Yuichiro KUMAMOTO
Hideaki MAKI
Keitaro MATSUMOTO
Hiroshi MATSUNAGA
Yutaka MICHIDA
Takashi MIYAO
Akihiko MURATA
Toshiya NAKANO
Shin-ichiro NAKAOKA
Hisashi NARITA
Hajime OBATA
Hiroshi OGAWA
Shigeyoshi OTOSAKA
Satoshi OZAWA
Hiroaki SAITO
Daisuke SASANO
Hironori SATO
Mitsuhide SATO
Souichiro SUEYOSHI
Toshio SUGA
Koji SUZUKI
Toru SUZUKI
Mitsuhiro TORATANI
Takenobu TOYOTA
Hiroshi UCHIDA
Yu UMEZAWA
Taichi YOKOKAWA
Takeshi YOSHIMURA

Japan Agency for Marine-Earth Science and Technology/
Institute of Environmental Radioactivity, Fukushima University(for Vol.1 Chap.1; Vol.3 Chap.2; Vol.9 Chap.1)
Japan Agency for Marine-Earth Science and Technology/
University of Tsukuba (for Vol.1 Chap.2; Vol.1 Chap.4; Vol.3 Chap.2 rev)
National Institute for Environmental Studies
Japan Agency for Marine-Earth Science and Technology
Tokyo University of Marine Science and Technology
Japan Meteorological Agency
Meteorological Research Institute, JMA
Japan Fisheries Research and Education Agency
Marine Works Japan Ltd.
Japan Agency for Marine-earth Science and Technology
University of Yamanashi
Graduate School of Frontier Sciences /Atmosphere and Ocean Research Institute, The University of Tokyo
Meteorological Research Institute, JMA
Japan Agency for Marine-Earth Science and Technology
Japan Agency for Marine-Earth Science and Technology
National Institute for Environmental Studies
Marine Works Japan Ltd.
Marine Works Japan Ltd.
Atmosphere and Ocean Research Institute, the University of TokyoJapan Meteorological Agency
Japan Agency for Marine-Earth Science and Technology
Japan Meteorological Agency
National Institute for Environmental Studies
Tokai University
Atmosphere and Ocean Research Institute, the University of Tokyo
Atmosphere and Ocean Research Institute, the University of TokyoJapan Atomic Energy Agency (for Vol.5 Chapt.1; Vol.5 Chapt.2; Vol.5
Chapt.3; Vol.5 Chapt.4; Vol.5 Chapt.6; Vol.9 Chapt.2)
The University of Tokyo (for Vol.5 Chapt.5)
Marine Works Japan Ltd.
Atmosphere and Ocean Research Institute, the University of TokyoJapan Meteorological Agency
Marine Works Japan Ltd.
Graduate School of Agricultural and Life Sciences,
the University of Tokyo
Nippon Marine Enterprises, Ltd.
Graduate School of Science and Faculty of Science, Tohoku University
Hokkaido University
Marine Information Research Center, Japan Hydrographic Association
Tokai University
Hokkaido University
Japan Agency for Marine-Earth Science and Technology
Tokyo University of Agriculture and Technology
Japan Agency for Marine-Earth Science and Technology
Central Research Institute of Electric Power Industry

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List of the reviewers at the time of review work
Kentaro ANDO
Michio AOYAMA
Hideki FUKUDA
Koichi GOTO
Ken IKEHARAJoji ISHIZAKA
Hideki KAERIYAMA
Yohei KAYUKAWA
Naohiro KOSUGIAtsushi KUBO
Yuichiro KUMAMOTO
Masashi KUSAKABE
Tsuyoshi MATSUMOTO
Akihiko MURATA
Toshiya NAKANO
Ayako NISHINA
Kazuhiro NORISUE
Jun NISHIOKA
Hajime OBATA
Stephen OBROCHTA
Takashi OTA
Shigeyoshi OTOSAKA
Daisuke SASANO
Mitsuhide SATO
Koji SEIKE
Yugo SHIMIZU
Toshio SUGA
Koji SUZUKIJames SWIFT
Shigenobu TAKEDA
Hiroyuki TANAKA
Atsushi TSUDA
Hiroshi UCHIDA
Kazuyuki UEHARA
Yu UMEZAWA
Shuki USHIO
Hisayuki YOSHIKAWA
Takeshi YOSHIMURA

Japan Agency for Marine-Earth Science and Technology
Japan Agency for Marine-Earth Science and Technology/
Institute of Environmental Radioactivity, Fukushima University
Atmosphere and Ocean Research Institute, the University of TokyoKANSO Co. Ltd.
National Institute of Advanced Industrial Science and Technology
Nagoya University
Japan Fisheries Research and Education Agency
National Institute of Advanced Industrial Science and Technology
Meteorological Research Institute, JMA
Shizuoka University
Japan Agency for Marine-earth Science and Technology
Marine Ecology Research Institute
University of the Ryukyus
Japan Agency for Marine-earth Science and Technology
Japan Meteorological Agency
Kagoshima University
Niigata University
Hokkaido University
Atmosphere and Ocean Research Institute, the University of Tokyo
Akita University
Ishinomaki Senshu University
Japan Atomic Energy Agency
Meteorological Research InstituteNagasaki University
National Institute of Advanced Industrial Science and Technology
Japan Fisheries Research and Education Agency
Graduate School of Science and Faculty of Science, Tohoku
University
Hokkaido University
Scripps Institution of Oceanography, UC San Diego
Nagasaki University
National Research Institute of Fisheries and Environment of InlandSea, Japan Fisheries Research and Education Agency
Atmosphere and Ocean Research Institute, the University of TokyoJapan Agency for Marine-Earth Science and Technology
Tokai University
Graduate School of Fisheries and Environment Sciences, Nagasaki
University
National Institute of Polar Research
Hokkaido University
Hokkaido University

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Table of Contents
Foreword for the 4th edition
Foreword for the 3rd edition

Foreword for the 2nd edition
Foreword
List of the authors
List of the reviewers
Vol. 1

Quality Control and Standard Materials

Chap. 1

Ocean Variables and the International
System of Units (SI)
Device for measurement andmeasurement standard (Etalons)

G101EN:001-006

Michio AOYAMA

G102EN:001-012

Chap. 3

Essential Ocean Variables (EOVs) of
GOOS

G103EN:001

Chap. 4

Quality control by comparison withstandards, control charts, duplicatedmeasurements, and property-property
characteristics, and the report ofmetadata
Data Publication and International
Exchange
Calculation of the Thermophysical
Properties of Seawater (2010)

G104EN:001-134

Michio AOYAMA
Hiroshi UCHIDA
Akihiko MURATA
Kazuhiko HAYASHI
Masao ISHII
Toshio SUGA
Sanae CHIBA
Michio AOYAMA
Hiroshi UCHIDA
Daisuke SASANO
Hajime OBATA

Chap. 2

Chap. 5
Chap. 6

G105EN:001-008
G106EN:001

Toru SUZUKI
Yutaka MICHIDA

Vol. 2

Physical Observation

Chap. 1

Water Sampling

G201EN:001-019

Chap. 2
Chap. 3
Chap. 4
Chap. 5

Water Temperature
Salinity
Density of SeawaterTransparency

G202EN:001-002
G203EN:001
G204EN:001-002
G205EN:001

Vol. 3

Seawater Analysis I (Dissolved Substances)

Chap. 1

Dissolved Oxygen

G301EN:001-033

Yuichiro KUMAMOTO
Daisuke SASANO
Hironori SATO
Keitaro MATSUMOTO

Chap. 2The precise and accurate
determination of dissolved inorganic
nutrients in seawater, using
Continuous Flow Analysis methods

G302ENr1:001

Michio AOYAMA

Chap. 3

Trace Metals

G303EN:001-005

Hajime OBATA

Toshiya NAKANO
Hajime OBATA
Kenichi KATAYAMA
Satoshi OZAWA
Hiroshi MATSUNAGA
Toshiya NAKANO
Takeshi KAWANO
Hiroshi UCHIDA
Toshiya NAKANOChap. 4

Determination of total dissolved
inorganic carbon in sea water
Determination of total alkalinity in sea
water by spectrophotometry
Determination of the pH of sea water
Determination of p(CO2) in air that isin equilibrium with a discrete sample
of sea water
Chlorofluorocarbons and Sulfur
Hexafluoride

G304EN:001

Chap. 9Carbon isotopic ratios (Δ14C, δ13C) of
dissolved inorganic carbon

G309EN:001-019

Chap. 10

Dissolved organic carbon (DOC),
nitrogen (DON), and phosphorus(DOP)

G310EN:001

Vol. 4

Seawater Analysis II (Particulate Substances)

Chap. 1

Particulate organic carbon (POC),
particulate nitrogen (PN), andparticulate phosphorus (PP)
Biogenic Silica
Carbon and Nitrogen Stable Isotopes
in Particulate Organic Matter
Algal pigments
Prokaryote and Heterotrophic
Nanoflagellates
Direct Counting Methods ofProkaryote and Heterotrophic
Nanoflagellates by Epifluorescence
Microscopy

Chap. 5
Chap. 6
Chap. 7
Chap. 8Chap. 2
Chap. 3
Chap. 4
Chap. 5
Chap. 5-1

Chap. 5-2

G305EN:001-012
G306EN:001
G307EN:001

Masao ISHII
Naohiro KOSUGI

G308EN:001
Yuichiro KUMAMOTO
Takafumi ARAMAKI
Hiroshi OGAWA

G401EN:001-006

Takeshi YOSHIMURA

G402EN:001-003
G403ENr1:001-009

Fuminori HASHIHAMAYu UMEZAWA

G404EN:001-005

Koji SUZUKI

G4051EN:001-006

Taichi YOKOKAWA

G4052EN:001-004

Mitsuhide SATO

under writing
G407EN:001-003

Koji SUZUKI

Chap. 6
Chap. 7

Enumeration of prokaryotes by flow
cytometry
Determination of Micro Zooplankton
Primary Production

Vol. 5

Sediment Analysis

Chap. 1

Seabed sediment sampling

G501EN:001-003

Chap. 2

G502EN:001-013

Chap. 3

Physical properties of sediment (watercontent, bulk density and porosity)
Loss on ignition

Chap. 4

Grain size distribution

G504EN:001-020

Chap. 5Major Component

G505EN:001-018

Chap. 6

Pore Water

G506EN:001-006

Vol. 6

Plankton and Benthos

Chap. 1
Chap. 2

Plankton Net
Benthos

G503EN:001-003

G601EN:001-009
G602EN:001-006

Hisashi NARITA
Shigeyoshi OTOSAKA
Hisashi NARITA
Shigeyoshi OTOSAKA
Hisashi NARITA
Shigeyoshi OTOSAKA
Hisashi NARITA
Shigeyoshi OTOSAKA
Hisashi NARITA
Shigeyoshi OTOSAKA
Hisashi NARITA
Shigeyoshi OTOSAKA
Hiroaki SAITO
Shigeaki KOJIMAVol. 7

Underway

Chap. 1

Determination of p(CO2) in air that isin equilibrium with a continuous
stream of sea water

G701ENr1:001-003

Daisuke SASANO
Shin-ichiro NAKAOKA

Chap. 2
Chap. 3

Acoustic Doppler Current Profilers
Bathymetry

G702EN:001-005
G703EN:001-009

Chap. 4
Chap. 5
Chap. 6

Weather Observations
Sea Ice
Indirect radiation and aerosol optical
thickness

G704EN:001-085
G705ENr1:001-047
G706EN:001-007

Shinya KOUKETSU
Hiroshi UCHIDA
Souichiro SUEYOSHI
Toshiya NAKANO
Takenobu TOYOTA
Mitsuhiro TORATANI
Hiroshi KOBAYASHI

Vol. 8

Measurements by Sensors

Chap. 1
Chap. 2
Chap. 3TSG
XBT／XCTD
Conductivity-Temperature-Depth
profiler (CTD) (Blue-watermeasurements)

under writing
under writing
G803EN:001

Chap. 4

Conductivity-Temperature-Depth
profiler (CTD)(coastal-water measurements)
CTD Oxygen Sensor Calibration
Procedures
Fluorometer
Turbidity Sensor andTransmissometer
Light fields and optical properties
Lowered Acoustic Doppler Current
Profiler (LADCP)

under writing

Chap. 5
Chap. 6
Chap. 7
Chap. 8Chap. 9Vol. 9Natural and Artificial Radioactivity

Chap. 1
Chap. 2

Radiometric Determination of
Anthropogenic Radionuclides in
Seawater samples
Seabed sedimentChap. 3
Chap. 4

Intentionally blank chapter.
Plankton and Benthos

Vol. 10

Marine Pollutant Observation

Chap. 1
Chap. 2
Chap. 3

Intentionally blank chapter.
Petroleum and Hydrocarbons
Microplastics (Surface Water Trawl
Surveys for Small Debris Items)
Floating Marine Pollutants (Shipboard
Sighting Surveys for Macro-Debris
Items)
Persistent Organic Pollutants

Chap. 4
Chap. 5

List of editors of each volume

G805EN:001
under writing
under writing
under writing
G809EN:001-007

Shinya KOUKETSU

G901ENr1:001-014

Michio AOYAMA

G902EN:001-008

Shigeyoshi OTOSAKA
Hisashi NARITA

G904EN:001-005

Hideki KAERIYAMA

G1002EN:001-019
G1003EN:001-009

Hideaki MAKI
Takashi MIYAO

G1004EN:001-009

Takashi MIYAO

under writing

This page left intentionally blank.

G101EN-1

Ocean variables and the International system of units (SI)‫ۑ‬Michio AOYAMA (Research and Development Center for Global Change (RCGC) Japan Agency for MarineEarth Science and Technology/ Institute of Environmental Radioactivity, Fukushima University

1. Introduction
The International System of Units (SI) consists of seven base units for length, mass, time, electric
current, thermodynamic temperature, amount of a substance, and luminous intensity. The corresponding
and clearly defined units (and their symbols) are the meter (m), kilogram (kg), second (s), ampere (a),kelvin (K), mole (mol), and candela (cd).
An instrument is calibrated with a working standard, and the working standard is calibrated with areference standard that is more precise (smaller uncertainty) than the working standard. If there is an
unbroken chain of calibration that reaches the International System of Units (SI), the result of ameasurement with the instrument is said to be traceable to the SI.
Instruments used for all ocean observations should, in principle, be explicitly traceable to the SI. For
each instrument there should be a system chart traceable to the SI. For example, Figure 1 shows a
traceability system chart for mass at a research institution that would be relevant if a scientist were
performing certification work with reference material for nutrient concentrations in seawater. As shownin Figure 1, all of the instruments used to measure weight, temperature, pressure, and the ambient
humidity in the room containing the electronic balance must have a certificate that is traceable to the SI.
The word "uncertainty" has been used since the early 1990s to characterize the reliability ofmeasurement data. Conventionally, concepts such as "error" and "accuracy" have been used tocharacterize the reliability of a measurement. The terminology, however, has varied among scientificfields and between countries. The Certificate in Investment Performance Measurement Program has
tried to unify the methods used to assess and express the reliability of measurement data. The result has
been a publication by the Joint Committee for Guides in Metrology (JCGM) that reflects the opinionsof the seven major international organizations involved in scientific measurements: “Evaluation of
measurement data—Guide to the expression of uncertainty in measurement” (JCGM 100, 2008).
This document is often referred to as the Guide to Uncertainty in Measurement or GUM. The GUM
describes in detail the procedure for the quantitative assessment of the uncertainty of a measurement,i.e., the degree of ambiguity of the knowledge obtained from a measurement. The basic idea is to allocate
the uncertainty to two components. Type A uncertainty is associated with conventional statisticalanalysis and is quantified by calculating the standard deviation of the data. Type B uncertainty is
estimated from various sources of information other than the information used to calculate the type A
uncertainty. The combination of the type A and type B uncertainty is the whole uncertainty. It is
important to consider various metrics of the technical reliability of the measurement data. These metrics
are then adapted for use in academic publications.

An assessment of uncertainty is also required in the

ISO 9000 document (Quality management systems—Fundamentals and vocabulary) of the International
Organization for Standardization and the ISO 17025 document (General requirements for competence
Guideline of ocean observations Vol. 1 Chap. 1 © Michio AOYAMA 2016 G101EN:001-006

G101EN-2

of calibration and testing laboratories).
In section 2, ocean variables in this Guideline are described in the context of the seven SI metrics oflength, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous
intensity. Section 2 discusses the relationship between the international system of measurement andcertified reference materials. Section 3 provides an example of a comprehensive traceability system ofmass at an institute.

2. Relationship between the observed ocean variables and the SI
Table 1 shows the relationships between ocean variables and the SI described in Volumes 2, 3, and
9 of this guideline. When certified reference materials are obtained and associated methods ofmeasurement for each ocean variable are used to calibrate measurement instruments, comparability of
the results of measurements of ocean variables can be obtained. However, for a standard referencematerial such as the number of moles of a substance, it has been difficult in practice to ensurecomparability of observed amounts. In addition, because receiving a calibration certificate is relatively
expensive, full traceability cannot always be achieved.
However, an effort should be made to have measurements of ocean variables traceable to the SI. An
exception is the liter, a non-SI metric of volume. In SI units, 1 liter should 1 dm3 or 10–3 m3. Althougha liter is not an SI unit, it is acceptable to continue to use liter as a metric of volume in an appropriate
context (BIPM, 2006). However, the conversion from volume of water to mass of water requires
knowledge of the density of the water. Therefore, a report of a quantity per liter should be accompaniedby the temperature and salinity of the seawater at the time of the measurement.

Guideline of ocean observations Vol. 1 Chap. 1 © Michio AOYAMA 2016 G101EN:001-006

Time
Location

Guideline of ocean observations Vol. 1 Chap. 1 © Michio AOYAMA 2016 G101EN:001-006

UTCnaturalradioactivity
and artificial
radioactivity

Watersampling
analysis
䠄Dissolved
state䠅

Universal Time, CoordinatedPlankton benthos/DUJHRUJDQLVPVSea water
Marine sediment

DIC
Talk
pH
pCO2
CFC, SF6
C-13
C-14
DOC/DON/DOP

Bq m-3
Bq kg-1
Bq kg-1
Bq kg-1

䈑mol kg-1

ʅatm
mol kg-1
䈑mol kg-1
nM
mol kg-1
mol kg-1

7UDFHPHWDO

mol kg-1

Bq kg-1

TEOS-10kg m-3Pam

Nutrient

ITS-90
TEOS-10UTC
WGS-84㻌㻭㼘㼠㼑㼞㼚㼍㼠㼕㼢㼑 global㼡㼚㼕㼠㼟standard

Degree.C

y/m/d/min/second/
degreeDissolved oxygen

Water temperature
Salinity
Density㻼ressure㼀ransparency

3K\VLFDOREVHUYDWLRQTime and
Location

Observables

Reported volulme
unit

VPDB
"1890 wood"

SIO CRM

NMIJ KIO3
SCOR, NMIJ and KANSO
CRM

SPRT
IAPSO Standard seawaterStandard instrument or
standard substanceBasicquantity

LengthLength

Meter
m

Unit
SymbolBasicquantity

LengthL

Basicquantity
Symbol

-3

-1

-3

-3
-1
1

Mass

Mass

1,-1

Kilogram
kg

Mass
M

-1
-1
-1
-1

-1

1
-1

-1
-1

-1

-1

1
1

Time

Time

-1
-1
-1
-1

-2

-2

Seconds

Time
TElectric
current

Electric
current

ampereA

Temerature

Temerature

KelvinK

Electric curreTemerature
I
theta

1

1

1

Amountofsubstan
ce

1,-1
1,-1

1
1
1
1

1

Amountofsubstan
ce

mole
mol

Amountofsubstance
NLuminous
intensity

Luminous
intensity

Candelacd

Luminous
intensity
J

G101EN-3

Table1. Relationship between ocean variables and the SI

G101EN-4

3. An example of a complete traceability system
All observed ocean variables should, in general, be explicitly traceable to the SI. In the case of an
instrument that measures mass, the traceability system chart should be available to facilitate traceability
to the SI. As an example, Figure 1 shows the traceability system chart for mass measurements at a
research institution that would be used to authenticate the certification of a reference material for
nutrients in seawater. All weights and the balance to be used (Figure 1) as well as all the equipment formeasuring room temperature, air pressure, and humidity must have a valid calibration certificate. Thisrequirement implies that it is possible to calculate the whole uncertainty of the mass measurement. Table
2 shows the results of the calculation of the whole uncertainty associated with preparation of a certain
solution. The results show that the uncertainties due to the weight and balance are small. However, theuncertainties due to the water temperature at the time of calibrating the volumetric flask and the room
temperature at the time of making the buoyancy correction are relatively large. Thus, by estimating themagnitude of the uncertainty for each individual factor, it is possible to estimate the magnitude of theuncertainty of ocean variables, and it becomes possible to formulate a procedure to reduce theuncertainties of those variables.

Guideline of ocean observations Vol. 1 Chap. 1 © Michio AOYAMA 2016 G101EN:001-006

㻿㻷㻙㻸㻞㻜㻜㼀㻴䃐㻰䚷㻗䚷㻿㻷㻙
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G101EN-5

Figure 1. An example of a complete traceability system chart for mass

Guideline of ocean observations Vol. 1 Chap. 1 © Michio AOYAMA 2016 G101EN:001-006

G101EN-6

Table 2. An example of an uncertainty budget for mass

Weight g

Mass
Mass

equipment
100
200Type of uncertainty
Type A
Type A

Non-linearity of the balance

Mass

BP210D_210g

Type B

Precision of the balance

Mass

200

Buoyancy correction

room temperature

Type B 䠄rectangle䠅

20 Υ

Atmospheric pressure

Type B 䠄rectangle䠅

1013.25 hPa

Humidity
Water temperature

Type B 䠄rectangle䠅
Type B 䠄rectangle䠅

50 %
20 Υ

Water temperature

Uncertanity
Weight g

Value
100 g
200 g
200 g

Type A 䠄10 times repeated䠅 199.99959 g

Divisor䠄probability
distribution䠅

Sensitivity coefficient

standard
uncertainty
relativevalue(%)

Mass

0.000045 g

2

2

1

0.0000225

Mass

0.0001 g

22

10.000025

Non-linearity of the balance

Mass0.0002¥

1.732050808

10.0000577

Precision of the balance
Buoyancy correction

Massroom temperature

5.67646E-05 g
0.5 Υ

1
¥

1
1.732050808

1
3.87E-06 ml㺃ml-1࣭K-10.0000284
0.00000559

Atmospheric pressure

0.081 hPa¥

1.732050808

1.04E-06 ml㺃ml-1࣭hPa-1

4.82E-09

3 %¥

1.732050808

9.26E-08 ml㺃ml-1࣭%-10.000000321

0.04 Υ

2

20.000118 ml㺃ml-1࣭K-10.0000118

Humidity
Water temperature

Water temperature

References
BIPM (Bureau international des poids et mesures). 2006. The International system of units (SI), 8th edition.
JCGM (Joint Committee for Guides in Metrology) 100. 2008. Evaluation of measurement data í*XLGHWR
the expression of uncertainty in measurement, 1st edition.

AcronymUTC

Universal Time, Coordinated

WGS-84

World Geodetic System, WGS1984

ITS-90The International Temperature Scale 1990

TEOS-10

Thermodynamic Equation Of Seawater - 2010 (TEOS-10)

Guideline of ocean observations Vol. 1 Chap. 1 © Michio AOYAMA 2016 G101EN:001-006

G102EN-1

Device for measurement and measurement standard (Etalons)〇Michio AOYAMA (Japan Agency for Marine-Earth Science and Technology, andUniversity of Tsukuba)
Hiroshi UCHIDA (Japan Agency for Marine-Earth Science and Technology)
Akihiko MURATA (Japan Agency for Marine-Earth Science and Technology)
Kazuhiko HAYASHI (Japan Meteorological Agency)
1. Introduction
Ensuring that there are procedures over measurements of ocean variables requires reliable
and stable measuring instruments, correct measurement methods, and measurement standards.
A measurement standard is frequently used as a reference in establishing values of measured
quantities and determining associated measurement uncertainties for other quantities of thesame kind. In this way, metrological traceability is established through calibration of othermeasurement standards, measuring instruments, or measuring systems [International
VocabularyofMetrology,
VIM,
ISO/IEC
Guide
99:2007,https://isotc.iso.org/livelink/livelink/fetch/2000/2122/4230450/8389141/ISO_IEC_Guide_99_
2007_%28Bilingual%29_%2D_International_vocabulary_of_metrology_%2D%2D_Basic_an
d_general_concepts_and_associated_terms_%28VIM%29.pdf?nodeid=8389169&vernum=-2
accessed on 5 March 2020]. Determining the value indicated by a measuring instrument or thevalue of an actual measuring instrument and its uncertainty based on a measurement standard
is called calibration. Comparability of measurements of ocean variables can be secured throughcalibration.
Section 2 of this chapter defines key terms related to standards based on VIM. In section 3
we outline device for measurement and measurement standard (Etalons). Then we present
procedures for measurement of temperature, pressure, salinity, oxygen, nutrients, total
dissolved inorganic carbon, alkalinity, pH and density. Eight of 9 parameters are common
parameters in hydrographic observations and these are listed as level 1 data of GO-SHIP cruises( Core Measurements, Categories and Submission Timelines ; https://www.goship.org/DatReq.html accessed on 5 March 2020) and defined as that level 1 data are of highest
priority to fulfill the scientific objectives of the GO-SHIP cruises. We also describe density inthis chapter because direct measurement of density might become an important parameter inhydrographic observations when we consider a link between salinity and density.
2. Terms related to standards
Terms related to standards are defined as part of the VIM. Definitions of the main terms related
to this chapter are as follows.
RM (Reference Material): material, sufficiently homogeneous and stable with reference to
Guideline of Ocean Observation Vol.1 Chap.2 Quality control with standard equipment and materials© Michio Aoyama, Hiroshi Uchida, Akihiko Murata, Kazuhiko Hayashi 2019 G102EN:001-012

G102EN-2

specified properties, which has been established to be fit for its intended use in measurement
or in examination of nominal properties
CRM (Certified Reference Material): reference material, accompanied by documentation issued
by an authoritative body and providing one or more specified property values withassociated uncertainties and traceabilities, using valid procedures
Primary standard: measurement standard established using a primary reference measurement
procedure, or created as an artifact, chosen by convention
Secondary standard: measurement standard established through calibration with respect
to a primary measurement standard for a quantity of the same kind
Uncertainty: non-negative parameter characterizing the dispersion of the quantity values being
attributed to a measurand, based on the information used
Calibration: operation that, under specified conditions, in a first step, establishes a relation
between the quantity values with measurement uncertainties provided by measurement
standards and corresponding indications with associated measurement uncertainties and, ina second step, uses this information to establish a relation for obtaining a measurement
result from an indication
Traceability: property of a measurement result whereby the result can be related to a reference
through a documented unbroken chain of calibrations, each contributing to the measurement
uncertainty
Metrological comparability: comparability of measurement results, for quantities of a given
kind, that are metrologically traceable to the same reference
3. Device for measurement and measurement standard (Etalons) for ocean
observations
Table 1 summarizes the device for measurement and measurement standard (Etalons) for
basic ocean observations. Table 1 outlines the standard instrument, reference material andmeasuring instrument for 9 variables. In addition, Table 2 shows the accuracy and/or
measurement uncertainties targeted by high-quality ocean observations based on Hood (2010)and stated accuracy/uncertainty in Essential Ocean Variables, EOV, identified by the GOOS
ExpertPanelsforoxygen,nutrients
andcarbonatesystemparameters(https://www.goosocean.org/index.php?option=com_content&view=article&id=14&Itemid=1
14, accesed on 5 March 2020). For details, please refer to the corresponding chapters of thisGuideline of Ocean Observations.

Guideline of Ocean Observation Vol.1 Chap.2 Quality control with standard equipment and materials© Michio Aoyama, Hiroshi Uchida, Akihiko Murata, Kazuhiko Hayashi 2019 G102EN:001-012

G102EN-3

Table 1. Device for measurement and measurement standard (Etalons) for basic ocean observations
Variables

Standard
instrument

Reference material

Measuring
instrument

Remarks
ITS-90.

TemperatureStandard
Platinum
Resistance
Thermometer

Temperature
sensorPressureDeadweightpiston gauge

Pressure sensor

Salinity

OxygenNutrientsa

IAPSO
seawaterSalinometer,
standard
conductivity
sensorNMIJb CRM (KIO3
solution)

NMIJb CRM KANSOc
CRM
SCOR-JAMSTECd
CRM

A standard thermometerfor deep sea that does notdepend on pressure can beused for in situ calibrationof temperature sensors.

Calculated from TEOS-10
from temperature andelectrical conductivity
values.

The amount of dissolved
oxygen is obtained
indirectly by titrating
Titration device, produced iodine
oxygen sensor corresponding to theamount of dissolved
oxygen with a sodium
thiosulfate solution.
Gas-segmented
continuous flow
analyzer

Total
dissolved
inorganic carbon

SIOe CRM

Coulometer

Alkalinity

SIO CRM

Titration devicepH

Calculated from theSpectrophotome
absorption spectrum of theterindicator chemical.

DensityVibrating-tube
density meter

Pure water

Measure density
difference between purewater and seawater
samples.

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G102EN-4

aInternational Association for the Physical Sciences of the OceansbNational Meteorology Institute of Japanc

KANSO Company, Ltd.

dScientific Committee on Ocean Research–Japan Agency for Marine-Earth Science and TechnologyeScripps Institute of Oceanography

Table 2. Accuracy and/or measurement uncertainties for high-quality ocean observations. Hood (2010)
does not use the concept of uncertainty but considers accuracy as an expanded uncertainty.
Variables

Uncertainty

Remarks

Thermometer

0.002 °C

Hood (2010)

Conductivity sensor

Hood (2010)

Pressure sensor

0.002 g kg−1
3 dbarOxygen sensor

1%

Hood (2010)

Practical salinity

0.001

Hood (2010)

Oxygen0.5 µmol kg−1

Hood (2010)

EOV: ship-based repeat hydrography−1

Nitrate0.03 µmol kg

Phosphate

0.005 µmol kg

EOV: ship-based repeat hydrography−1−1

EOV: ship-based repeat hydrography

Silicate

0.1 µmol kg

EOV: ship-based repeat hydrography

Total dissolved inorganic carbon

2 µmol kg−1

EOV: ship-based repeat hydrography−1

EOV: ship-based repeat hydrography

Alkalinity
pH
Density

2 µmol kg
0.005

EOV: ship-based repeat hydrography−30.002 kg m

Wolf et al. (in prep.)

3.1 Temperature
The current temperature standard is the International Temperature Scale of 1990 (ITS-90).
In ITS-90, the temperature scale is defined by fixed points, an interpolation instrument, and aninterpolation formula divided into several temperature regions. In the temperature range for
actual ocean observations, temperature scales are defined based on two fixed points—the triple
point of water (0.01 °C) and the melting point of gallium (29.7646 °C)—and the Standard
Platinum Resistance Thermometer (SPRT).
The traceability system of temperature to Le Système international d'unités (SI) is basedon ITS-90. By calibrating with a SPRT, traceability to the SI of the thermometer is ensured. SI
traceable thermometers are available, and SI traceable calibration is available in Japan as wellas in many other countries.
In practice, the temperature of the seawater (water temperature) is measured when thethermometer indicates the temperature of the seawater after thermodynamic equilibrium is
Guideline of Ocean Observation Vol.1 Chap.2 Quality control with standard equipment and materials© Michio Aoyama, Hiroshi Uchida, Akihiko Murata, Kazuhiko Hayashi 2019 G102EN:001-012

G102EN-5

established between the seawater and thermometer. Determining the time required forequilibrium requires consideration of the time constant associated with the heat capacity of thethermometer.
The temperature sensor (SBE 3plus) of the conductivity-temperature-depth (CTD)
instrument (SBE 9plus) is manufactured by Sea-Bird Electronics, a company whose
instruments are widely used for observations in the open ocean. The sensor can be calibrated
by the manufacturer to within an uncertainty of about 0.001 °C. However, some CTD
temperature sensors have a pressure dependence (up to 0.002 °C per 6000 dbar, Uchida et al.,2015), so care is needed when measuring the water temperature at depths greater than 2000
dbar. By comparing and calibrating the CTD temperature sensor based on the deep ocean
standard thermometer (SBE 35) manufactured by Sea-Bird Electronics in the deep ocean, thewater temperature in the deep ocean can be measured with an uncertainty of 0.0007 °C (Uchida
et al., 2015). For both the CTD temperature sensor and the deep ocean standard thermometer,
it is necessary to ascertain the temporal changes of the sensor characteristics from the historyof calibration by the manufacturer in the laboratory, etc., and to use the instrument calibrated
periodically in consideration of the required accuracy.

3.2 Salinity
Salinity is defined by the International Thermodynamic Equation of Seawater 2010 (TEOS10), and the IAPSO (International Association for the Physical Sciences of the Ocean) standard
seawater is the de facto standard of measurement. TEOS-10 estimates the absolute salinity (unit:
g kg−1) from the measured value of practical salinity (no units, Practical Salinity Scale of 1978:
PSS-78) defined by the electrical conductivity ratio.
3.2.1 Salinometer and IAPSO standard seawater
Practical salinity is measured with an electrical conductivity salinometer (for example, the
AUTOSAL 8400B manufactured by Guildline Instruments is widely used). Calibration of theelectrical conductivity salinometer should be conducted by measuring the conductivity of
IAPSO standard seawater with an assigned value of the electrical conductivity ratio. In practice,
the salinity of seawater is determined from electrical conductivity by introducing seawater into
the cell inside the equipment. Alternatively, the electrical conductivity is measured by inserting
an electrical conductivity sensor into the target seawater, and the conductivity is then converted
to practical salinity. Temperature has a large effect on the measurement of electricalconductivity. For precise salinity measurements, the precision of the temperature measurement
must be controlled so that it is consistent with the degree of uncertainty required for the salinity
measurement. Specifically, when the set temperature of the electrical conductivity salinometer
is T °C, it is important to ensure that the ambient temperature is in the range between T °C and
T minus 2 °C.
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G102EN-6

IAPSO standard seawater is surface seawater collected in the eastern North Atlantic Ocean.
The water is filtered, the organic matter decomposed, the electrical conductivity adjusted, etc.
The water is then stored in a glass bottle. The electrical conductivity ratio at 15 °C and 1 atm
for PSS-78 potassium chloride solution is then assigned (Bacon et al., 2007). However, it has
been pointed out that there is an uncertainty of about 0.001 in terms of practical salinity in theK15 value that is assigned (Kawano et al., 2006). To study changes of salinity in the deep ocean,care must therefore be taken. During a cruise, it is important to calibrate the conductivity
salinometer using a single batch of IAPSO standard seawater and to report the batch number of
the IAPSO standard seawater used for the salinity measurement.
3.2.2 conductivity sensor
In general, the output value of the electrical conductivity sensor is more likely than the
output value of the temperature sensor or pressure sensor to shift suddenly because of a physicalimpact or to shift slowly because of contamination of the cell. For the conductivity sensor, there
is also a pressure dependence that cannot be evaluated by laboratory calibration. To correct forthis pressure dependence, it is necessary to compare and calibrate the CTD electricalconductivity sensor by using salinity data measured for in situ water samples for high-quality
ocean observations. The salinity uncertainty associated with the CTD conductivity sensor
therefore depends on the uncertainty of the salinity of the seawater sample and the sensor
calibration method.
3.2.3 Practical salinity calculation
Calculating practical salinity from the conductivity ratio of the electrical conductivity
sensor requires knowing the ratio of the electrical conductivity to the electrical conductivity ata practical salinity of 35, temperature of 15 °C (the International Practical Temperature Scale
1968: IPTS-68), and pressure of 0 dbar. For the value of the above electrical conductivity ratio,
TEOS-10 adopts the value of 4.29140 S/m reported by Culkin and Smith (1980). This value isalso used in the calibration of electrical conductivity sensors at Sea-Bird Electronics, butdifferent values may be used, depending on the manufacturer. For example, 4.2896 S/m is used
for Tsurumi Seiki XCTD. These different values are not a problem when using the software
provided by the manufacturer to calculate salinity, but care must be taken when the user iscalculating the salinity using homemade software.
3.3 Pressure
For pressure, a system of standard mass has been established by the Metre Convention, anda dead weight piston gauge is used as the primary standard for pressure. The SI traceability ofthe pressure is ensured by comparing and calibrating with the piston gage. Alternatively, pistongauges can be calibrated as SI traceable. In recent years, high-precision digital pressure gauges
with excellent stability (for example, quartz vibration type pressure gauges manufactured by
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Paroscientific, Inc.) have been available, and they can be incorporated into standard pressure
systems (Kobata et al., 2011). Such gauges have also been used as digital pressure calibrators(for example, the E-DWT manufactured by Fluke) to ensure SI traceability.
The quartz crystal resonator pressure gauge available from the Paroscientific, Inc. is also
used in the Sea-Bird Electronics CTD (SBE 9plus) pressure sensor, which is widely used forobservations in the open ocean. Quartz crystal resonator pressure gauges have lower hysteresis(the characteristic of outputting different values when pressure is increasing and when pressure
is decreasing) and are very stable. Proper calibration of the pressure sensor before a cruise
ensures that the pressure can be measured to within an uncertainty of about 0.02%, and there is
generally no need to correct measured data. The temporal drift and shift of the CTD pressure
sensor can be monitored using values of atmospheric pressure (deviation from standard
atmospheric pressure) measured on the deck before and after making CTD observations. If thedifference between the values measured on the deck before and after a CTD observation is large(for example, about 1 dbar), there is presumably a problem with the correction of thetemperature characteristics. In that case, calibration, including the temperature characteristics,
must be performed. Normally, calibration is performed only at room temperature, except forthe manufacturer’s calibration when the sensor is shipped to users. It is important to use a CTD
pressure sensor that has been calibrated periodically to ensure the required accuracy and toascertain the time-dependent characteristics of the sensor from the history of calibration in thelaboratory by the manufacturer and the user.
3.4 Oxygen
3.4.1 Titration
The method for determining the dissolved oxygen concentration in seawater is generally
the Carpenter method (Carpenter, 1965), which is an improvement of the Winkler method, but
is hereafter simply referred to as the Winkler method. In this Winkler method, manganesehydroxide “fixes” dissolved oxygen under alkaline conditions, and the “fixed” dissolved
oxygen quantitatively oxidizes iodine ions to free iodine under acidic conditions. Titrating thefree iodine with a sodium thiosulfate solution of known concentration indirectly quantifies thedissolved oxygen concentration.
The sodium thiosulfate solution concentration is determined by titration of a potassium
iodate solution of known concentration. In Japan, SI-traceable certified reference potassium
iodate standards are supplied by the National Meteorology Institute of Japan, National Instituteof Advanced Industrial Science and Technology (NMIJ). However, the dissolved oxygen
concentration determined by the Winkler method includes the concentration of interfering
substances in the seawater sample. Therefore, strictly speaking, the dissolved oxygen
concentration obtained by the Winkler method is not SI traceable unless the concentrations of
the interfering substances are also quantified at the same time for each seawater sample.
The Winkler method with an automatic titrator can measure dissolved oxygen to within astandard uncertainty of about 0.14 µmol kg−1 when the concentration is 250 µmol kg−1
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G102EN-8(Kumamoto et al., 2015). The measurement, however, does not include the effects of theseawater blank (the total effect of the substances in the seawater sample that interfere with the
Winkler method). With the exception of anoxic seawater, the seawater blank concentration in
the open ocean is equivalent to a dissolved oxygen concentration of 1 µmol kg−1 or less, but theblank cannot be ignored in high-precision observations, for which the target uncertainty might
be 0.5 µmol kg−1. Assuming that the seawater blank is 0.5 ± 0.5 µmol kg−1, the overall
uncertainty of the measured dissolved oxygen concentration, including the effect of theseawater blank, is estimated to be 0.6 µmol kg−1 when the true concentration is 250 µmol kg−1.
In such a case, however, it must be clearly stated that the reported concentration has beencorrected for the effect of the seawater blank (0.5 µmol kg−1).
3.4.2 Oxygen sensor
It is also common to measure the dissolved oxygen concentration continuously by attachingan oxygen sensor to the CTD. In general, the output of an oxygen sensor is likely to shift
because of contamination or deterioration of the oxygen detection membrane. There is also a
dependence on pressure that cannot be evaluated by laboratory calibration. For the oxygen
sensor of a CTD used in high-precision ocean observations, it is therefore necessary to calibrate
the oxygen sensor based on the dissolved oxygen concentration of the seawater sample
determined by the Winkler method in a manner analogous to the way an electrical conductivity
sensor is calibrated by salinity of the seawater sample measured by salinometer. The uncertaintyof the dissolved oxygen concentration determined by the CTD oxygen sensor therefore depends
on the uncertainty of the dissolved oxygen concentration of the seawater sample and the methodby which the sensor is calibrated.
3.5 Nutrients
The NMIJ has supplied SI traceable CRM for nutrients in seawater since June 2014. The
NMIJ CRM locates top of traceability and is primary standard. In addition, since June 2015, an
SI traceable CRM has been supplied by the KANSO Company, Ltd. (KANSO). The KANSO
CRM is secondary standard.
Nitrate, phosphate, and silicate concentrations of NMIJ CRM have been certified by three
analytical methods, including the colorimetric methods commonly used while those of KANSO
CRM are certified by colorimetric methods only (Aoyama, 2016).
In the NMIJ certification document, the mass fractions of nitrate ions and phosphate ions
are shown directly, and the mass fraction of silicon is shown as the mass fraction of dissolved
silica. In addition, the seawater density at 25 °C is shown as reference information. For
conversion to mol kg−1, the units normally used, it is necessary to convert from mass fraction
to molar concentration using the latest atomic weights at the time of issuance of the certificate.
Nutrient concentrations in seawater samples are assayed by adding reagents that produce acolor reaction, and the concentrations are determined quantitatively via a colorimetric methodthat calculates the concentration from the absorbance. At present, colorimetric analysis is
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performed mainly by continuous flow analysis (CFA) equipment (for example, the AutoAnalyzer manufactured by BL TEC K.K.).
When performing nutrient analysis by any method, it is necessary to explicitly measure
CRMs to ensure metrological comparability, hereafter comparability, and traceability. In
addition, the solution (CRM, inhouse standard solution, or deep-sea water as tracking standard,etc.) should have a concentration close to the maximum concentration of the analytical sample.
It is also essential to repeat the analysis a number of times so that a statistically significant value
is obtained (for example, the analysis may be repeated nine or more times) and to evaluate anddescribe the repeatability of the analysis at roughly that maximum concentration (expressed as
the standard deviation of the obtained value). In addition, the uncertainty of the analysis
depends on the concentration, and the uncertainty of the analysis increases at low concentrations.
It is therefore desirable to evaluate the uncertainty of the analysis at different concentrations
covering the full range of sample concentrations. When analyzed by a well-trained analyticalengineer using finely tuned analytical instruments, the reproducibility of nitrate, phosphate, andsilicate analyses (standard deviation of single assays) in the Pacific Ocean is less than 0.2% of
the concentration of which ranges were around 35-40 µmol kg−1 , 2.5-2.9 µmol kg−1 120-140µmol kg−1 for nitrate, phosphate, and silicate (N = 16).

3.6 Total dissolved inorganic carbon, alkalinity, and pH
For the measurement of total dissolved inorganic carbon and alkalinity, a CRM is available
from Prof. A. G. Dickson’s laboratory at the Scripps Institute of Oceanography (SIO),
University of California. The CRM is widely used for quality control of data. For themeasurement of pH, there is currently no CRM.
The widely used methods for high-precision measurements of total dissolved inorganiccarbon, alkalinity, and pH (Bockmon and Dickson, 2015) are described below. For total
dissolved inorganic carbon, a coulometric titration method using a coulometer is widely used.
This is a method in which dissolved inorganic carbon in a seawater sample is extracted ascarbon dioxide, absorbed in the cathode solution of an electrolytic cell, and accurately titratedusing a coulometer with hydroxide ions generated via electrolysis of water (Ishii et al., 2000).
For alkalinity, potentiometric acid titration using an open cell is widely used. This method is
published as international standard ISO 22719:2008 (Water quality – Determination of total
alkalinity in sea water using high precision potentiometric titration). A colorimetric method
using an indicator dye (m-cresol purple) and a spectrophotometer is widely used for pH
measurements. This method is also published as international standard ISO 18191:2015 (Water
quality – Determination of pH in sea water – Method using the indicator dye m-cresol purple).
Increasing the purity of the indicator by an appropriate technique makes it in principle
unnecessary to use a standard material, and the pH of seawater can be accurately measured.
Recently, 59 laboratories from around the world have participated in an inter-laboratory
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comparison experiment for measuring total dissolved inorganic carbon, alkalinity, and pH(Bockmon and Dickson, 2015). For total dissolved inorganic carbon and alkalinity, a CRM isused in almost all laboratories, and about half of the laboratories agree to within 5 µmol kg−1.
About 20–25% of the laboratories have high-precision instrumentation, and their uncertainty isless than 2 µmol kg−1. In other laboratories, when the concentration of a sample is close to theCRM concentration, the reported concentrations are consistent with one another, but for
samples with concentrations higher than the CRM, the reported values have shown greater
dispersion. The indication is that CRMs with higher concentrations are needed. In the case ofpH, there are large variations in measured values because there is no standard for pH, but themeasured values of seven laboratories using indicators with increased purity showed similarvalues within 0.004, and they were close to the target uncertainty (0.003) for high-precisionobservation.

3.7 Density
In Japan, a traceability system for density has been established with silicon single-crystals at
the top of traceability (Fujii, 2009). The density of seawater is usually measured with avibrating-tube density meter (the Anton-Paar DMATM 5000M is widely used in the field ofdensity measurements). Vibrating-tube density meters are usually calibrated with air and water,
and pure water standard solutions for calibration of SI-traceable density meters arecommercially available. However, the uncertainty of the density assigned to the pure water
standard solution is large (about 0.01 kg m−3) and cannot be used for precise measurements ofseawater density. The differences between the measured density values of pure water fromultrapure water production equipment and that of seawater samples should therefore be
determined first. The values obtained by calculation from the equation of state of water(IAPWS-95: the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary
Water Substance for General and Scientific Use, Wagner and Pruss, 2002) are then added tothe density of pure water to obtain the density of seawater (so called “substitution method”;
Wolf, 2008). However, because this equation of state is defined by the isotopic composition ofStandard Mean Ocean Water (SMOW), the density difference due to the deviation of the stable
isotope ratio (δ18O and δD) of pure water used for measurement from SMOW should becorrected.
Recently, the NMIJ has developed a hydrostatic weighing device (primary standard) forseawater density measurements using silicon single-crystals as a sinker. The SI-traceablecalibration of the density of standard seawater with that device has an uncertainty of 0.002 kg
m−3. At present, there is no standard seawater for measuring seawater density, but in order toensure comparability of measurements of the densities of seawater samples, the density of
IAPSO standard seawater, etc. should be measured together with the seawater samples in order
to compare the result with the calibrated density determined by the NMIJ. However, it should
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be noted that the density of IAPSO standard seawater increases with time due to dissolution ofsilicon from glass containers (0.0004 kg m−3 per year, Uchida et al., 2011).
References
Aoyama, M. (2016): Determination of dissolved nutrients (N, P, SI) in seawater with highprecision and inter-comparability using gas-segmented continuous flow analyzers.
Guideline of Ocean Observations, vol. 3, chap. 2, G302EN:001−095.
Bacon, S., F. Culkin, N. Higgs and P. Ridout (2007): IAPSO Standard Seawater: Definition of
the uncertainty in the calibration procedure, and stability of recent batches. J. Atmos.
Oceanic Technol., 24, 1785−1799.
Bockmon, E. E. and A. G. Dickson (2015): An inter-laboratory comparison assessing thequality of seawater carbon dioxide measurements. Marine Chemistry, 171, 36−43.
Carpenter, J.H. (1965): The Chesapeake Bay Institute technique for the Winkler dissolved
oxygen method. Limnology and Oceanography, 10, 141−143.
Culkin, F. and N. Smith (1980): Determination of the concentration of potassium chloride
solution having the same electrical conductivity, at 15˚C and infinite frequency, as standard
seawater of salinity 35.0000‰ (chlorinity 19.37394‰), IEEE J. Oceanic Eng., 5, 22−23.
Fujii, K. (2009): A new density standard replaced from water – Using silicon single-crystals as
the top of traceability in density measurement –. Synthesiology English edition, 3, 187−198.
Hood, E. M. (2010): Introduction to the collection of expert reports and guidelines. The GOSHIP Repeat Hydrography Manual: A Collection of Expert Reports and Guidelines, IOCCP
Report No. 14, ICPO Publication Series No. 134, Version 1.
Ishii, M., H. Y. Inoue and H. Matsueda (2000): Coulometric precise analysis of total inorganiccarbon in seawater. Technical Reports of the Meteorological Research Institute No. 41
doi:10.11483/mritechrepo.41 (in Japanese with English abstract)
Kawano, T., M. Aoyama, T. Joyce, H. Uchida, Y. Takatsuki and M. Fukasawa (2006): The
latest batch-to-batch difference table of standard seawater and its application to the WOCE
onetime sections. J. Oceanogr., 62, 777−792.
Kumamoto, Y., Y. Takatani, T. Miyao, H. Sato and K. Matsumoto (2015): Dissolved oxygen.
Guideline of Ocean Observations, vol. 3, chap. 1, G301JP:001−029 (English edition is inprep.)
Kobata, T. M., Kojima and H. Kajikawa (2011): Improvement of reliability in pressure
measurements and international mutual recognition – Incorporation of industrial digitalpressure gauges to the national metrology system –. Synthesiology, 4, 209−221. (in Japanesewith English abstract)
Uchida, H., T. Kawano, M. Aoyama and A. Murata (2011): Absolute salinity measurements ofstandard seawaters for conductivity and nutrients. La mer, 49, 119−126.
Uchida, H., T. Nakano, J. Tamba, J. Widiatmo, K. Yamazawa, S. Ozawa and T. Kawano (2015):
Deep ocean temperature measurement with an uncertainty of 0.7 mK. J. Atmos. Oceanic.
Guideline of Ocean Observation Vol.1 Chap.2 Quality control with standard equipment and materials© Michio Aoyama, Hiroshi Uchida, Akihiko Murata, Kazuhiko Hayashi 2019 G102EN:001-012

G102EN-12

Technol., 32(11), 2199–2210.
Wagner, W. and A. Pruss,(2002): "The IAPWS Formulation 1995 for the Thermodynamic
Properties of Ordinary Water Substance for General and Scientific Use," J. Phys. Chem.
Ref. Data, 31, 387-535.
Wolf, H. (2008): Determination of water density: limitations at the uncertainty level of 1×10−6.
Accred. Qual. Assur., 13, 587−591.
Wolf, H., S. Weinreben, H. Uchida and R. Pawlowicz: Best practice guide for the measurementof seawater density (in preparation under the activity of the Joint Committee on theProperties of Seawater, http://www.teos-10.org/JCS.htm)

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Essential Ocean Variables (EOVs) of GOOS
Masao ISHII(Oceanography and Geochemistry Research Department, Meteorological Research Institute)Toshio SUGA
(Graduate School of Science and Faculty of Science, Tohoku University)
Sanae CHIBA(Research and Development Center for Global Change,
Japan Agency for Marine-Earth Science and Technology)

The Global Ocean Observing System (GOOS), being sponsored by UNESCO/IOC, WMO, UNEP,
and ICSU, is a programme to coordinate observations around the global ocean for climate, ocean health,and real-time services. In accordance with the "Framework for Ocean Observing", GOOS defines
Essential Ocean Variables (EOVs) of physics, biogeochemistry, biology and ecosystems, the methodsof many of these measurements being guided in this Guideline.
The latest information and the list of GOOS EOVs are available with their specification sheets at thefollowing web site.
http://goosocean.org/index.php?option=com_content&view=article&id=14&Itemid=114

Guideline of ocean observation Vol. 1 Chap. 3© Masao ISHII7RVKLR68*$DQG6DQDH&+,%$ 2016 G103EN:001-001

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Quality control by comparison with standards, control charts, duplicated measurements, andproperty-property characteristics, and the report of metadata〇Michio AOYAMA1,2, Hiroshi UCHIDA1, Daisuke SASANO3, and Hajime OBATA4
1

Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science andTechnology (JAMSTEC)
2
Center for Research in Isotopes and Environmental Dynamics (CRiED), University of Tsukuba
3Japan Meteorological Agency (JMA)
4
Atmosphere and Ocean Research Institute (AORI), University of Tokyo
Abstract
High-quality data from observations in the ocean and the comparability and traceability ofobservational data with stated uncertainty are important requirements for oceanographic research. Now
we are able to obtain high-quality observational data that is comparable and traceable to the International
System of Units (Système International d'Unités, SI) with stated uncertainty for many of the variables
discussed in Volume 1, Chapter 2 of this guideline. This chapter describes 1) quality control procedures
necessary to obtain SI-traceable data with stated uncertainty, 2) metadata reporting, 3) best practices for
quality control implemented on a few cruises, 4) an introduction to software such as Ocean data view and2D/3D property-property plot for quality control, 5) improvement of data quality obtained along 137°E
from 10°–24°N (section P9) by the Japan Meteorological Agency since 1967 and some other examplesof improvement of obtained data.

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List of acronyms used in this chapter
Acronym

Meaning

AIC

Akaike Information Criterion

AORI

Atmosphere and Ocean Research InstituteChl. aChlorophyll a

CRiEDCenter for Research in Isotopes and Environmental Dynamics

CRM

Certified Reference Material

CSK

Cooperative Study of the Kuroshio and Adjacent Regions

CSR

Cruise summary report

CTD

Conductivity-temperature-depth

dbar

Decibar

DIC

Dissolved inorganic carbon

EEPROM

Electrically erasable programmable read-only memory

FS

Full scale

GaMP

Melting point of gallium

GLODAP

GLobal Ocean Data Analysis ProjectGO

General Oceanics

hPa

Hectopascal = 100 Pascals

IAPSO

International Association for the Physical Sciences of the Oceans

ICESInternational Council for the Exploration of the Sea

IOC

International Oceanographic Commission

IOCCP

International Ocean Carbon Coordination Project

ITS-90International Temperature Scale of 1990

JAMSTEC

Japan Agency for Marine-Earth Science and Technology

JCSS

Japan Calibration Service System

JFE

JFE Advantech Co., Ltd.

JMAJapan Meteorological Agency

K

Kelvin degree

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LAN

Local area network

NIST

National Institute of Standards and Technology

NMIJ

National Metrology Institute of Japan

Num

Number of measurements

ODV

Ocean Data View

Pa

Pascal (unit of pressure)

PACIFICA

Pacific ocean interior Carbon (the name of a dataset)

psia

Pounds per square inch absolute

QC

Quality control

RCGC

Research and Development Center for Global Change

RIGC

Research Institute for Global Change

RM

Reference material

ROSCOP

Report of Observations/Samples collected by Oceanographic Programmes

S

Siemens

SBE

Sea-Bird Electronics

SCOR

Scientific Committee on Oceanic Research

SEASOFT

Software Engineering of America software

SI

Système International d'Unités ( The International System of Units)

SIO

Scripps Institute of Oceanography

S/N

Serial number

SPRTStandard Platinum Resistance Thermometer

TA

Total alkalinity

TB

Teledyne Benthos

TC

Temperature-conductivity

TPW

Triple point of water

TSG

Thermosalinograph

WHP

WOCE Hydrographic Programme

WHPO

WOCE Hydrographic Program Office

WOCE

World Ocean Circulation Experiment

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Table of contents
1. Introduction...................................................................................................................................
2. Quality control procedures to obtain SI-traceable data with stated uncertainty ..........
2-1. Unbroken chain of comparison that can produce the best SI-traceable
instruments/materials..................................................................................................................
2-2. Pre- and post-cruise calibration of sensors and water sample measurements........
3. Metadata report and access to data by Intergovernmental Oceanographic
Commission (IOC) recommendations.....................................................................................

5
6
6
7
8

3-1. Cruise Summary Reports and metadata of the cruise.................................................
8
3-2. Metadata and examples of metadata of several cruises................................................
10
4. Best practices of quality control procedures for sensors in the case of the MR15-05 cruise by
JAMSTEC and the RF16-06 cruise by the JMA..................................................................
12
4-1. Quality control and calibration of sensors in the case of the MR15-05 cruise(JAMSTEC)..................................................................................................................................
12
4-2. Quality control and calibration of sensors in the case of the RF16-06 cruise(JMA) ..............................................................................................................................................
32
5. Best practices for quality control of bottle salinity, oxygen concentration, nutrient
concentrations, and carbonate system parameters................................................................
48
5-1. Quality control for bottle sampling parameters in the case of the MR15-05 cruise(JAMSTEC)...................................................................................................................................
48
5-2. Quality control for bottle sampling parameters in the case of the RF16-06 cruise(JMA) .............................................................................................................................................
58
5-3. Quality control for trace metals in seawater during the R.V. Hakuho Maru KH-09-5
cruise (AORI, University of Tokyo) .........................................................................................
96
5-4. General procedure of quality control flag assignment..................................................
99
6. Quality control by 2D/3D property/property plots by Ocean Data View........................
100
6-1. Recommended softwares....................................................................................................
100
6-2. 2D/3D property/property plot by ODV...........................................................................
100
7. History of a region, 32°–35°S and 178°–170°W, in the South Pacific Ocean:.evidence ofimprovement of data quality by different organizations.....................................................
103
8. History along the P09 section: evidence of improvement of quality of data collected by thesame organization........................................................................................................................
105
8.1 Comparability among stations............................................................................................
105
8.2 Comparability among cruises.............................................................................................
106
8.3 Use of nutrient CRMs...........................................................................................................
108
Acknowledgements.............................................................................................................................
109
References..............................................................................................................................................
109
Appendix................................................................................................................................................
113
I IOC data policy 2003.......................................................................................................................
114
II-1 Cruise summary report of KH-09-5........................................................................................
117
II-2 Post cruise metadata of the cruise KH-09-05.........................................................................
118
II-3 Cruise summary report, expanded version by R/V Ryofu Maru.....................................
121
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1

1. Introduction

2

High-quality data from observations in the ocean and the comparability and traceability of3

observational data with stated uncertainties are important requirements for oceanographic research. The

4

purpose of this Guideline of Ocean Observation, published by the Oceanographic Society of Japan, is5

to articulate how those requirements are to be met.

6

It is important and customary to share data obtained by various types of ocean observations, not only

7

for scientific research but also for a wide variety of other purposes, including the prediction of weather

8

and climate, the operational forecasting of the marine environment, the preservation of life, the9mitigation of adverse anthropogenic impacts on the marine and coastal environment, and the10advancement of scientific understanding that makes application of this information possible. The timely,

11

free, and unrestricted international exchange of oceanographic data requires that the data be

12accompanied by metadata (i.e., data about data).

13

The long history of quality control of observational hydrographic data by the oceanographic

14

community reflects the need to obtain high-quality data as much as possible. The World Ocean

15

Circulation Experiment (WOCE) era was the first period of time when systematic quality control of16

observational hydrographic data was done by the data originator and by reviewers. Examples include

17

the article review system, which was organized by the WOCE Hydrographic Program Office (WHPO).

18

Data originators submitted their cruise reports with data and its quality flag following

19“REQUIREMENTS FOR WOCE HYDROGRAPHIC PROGRAMME DATA REPORTING” (WOCE

20

Report 67/91, Joyce and Corry, 1994). Reviewers investigated all reported data by using MATLAB

21

scripts and/or graphic software written by collaborators of the WHPO activity. There is also good22

guidance in the document titled “REFERENCE-QUALITY WATER SAMPLE DATA Notes on

23

Acquisition,24

assets/documentation/policies/Data_Evaluation_reference.pdf , accessed 30 March 2020) by J. Swift at25

the Scripps Institute of Oceanography (Swift, 2010). .

RecordKeeping,and

Evaluation”(https://cchdo.github.io/hdo-

26

Today, we are able to have high-quality observational data that are comparable and traceable to the27

Système Internationale (SI) with stated uncertainty for many parameters, as stated in Volume 1, Chapter

28

2 of this guideline.

29

This chapter 4 of volume 1 covers the following topics: 1) description of quality control procedures

30

needed to obtain SI-traceable accuracy with stated uncertainty, 2) metadata reports, 3) examples of best31

practices of quality control conducted on a few cruises, 4) introduction of quality control software such32

as Ocean Data View and 2D/3D property-property plots for quality control, 5) improvement of the

33
34

quality of data obtained on cruises along 137°E from 10°–24°N (section P9) by the Japan Meteorological
Agency since 1967 and some other examples of improvement of obtained data.

35
36

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2. Quality control procedures to obtain SI-traceable data with stated uncertainty

38

2-1. Unbroken chain of comparison that can produce the best SI-traceable instruments/materials

39

We show basic quality control procedures for sensors and water sample measurements in sections 4

40

and 5, respectively. One of the basic goals of quality control is to ensure comparability and traceability

41

to the SI with stated uncertainty, as described in Vol 1, Chap 1 (Aoyama, 2016) and Vol 1, Chap 2

42entitled “Device for measurement and measurement standard (Etalons) “ (Aoyama et al., 2019) in this43

guideline.

44

Based on the SI traceability system, an unbroken chain of comparison is needed to achieve the best45

SI-traceable instruments/materials, e.g., a temperature primary standard based on the International

46

Temperature Scale of 1990 (ITS-90) for seawater temperature measurements and a silicon mass primary47

standard of mass for silicate concentration measurements. Our oceanographic

48

metrology community, through the national metrology institutes in each country, have traditionally49

provided primary measurement standards to underpin a wide range of physical and chemical

50

measurements. Temperature measurements are based on ITS-90 (traceable to SI using a standard

51

platinum resistance thermometer, SPRT). Comparability of salinity measurements has been ensured

52

using the International Association for the Physical Sciences of the Oceans (IAPSO) salinity standard

53

seawater provided by Ocean Scientific International, UK. Comparability and traceability of the54

carbonate system parameter measurements has been ensured using certified reference materials (CRMs)

55

provided by the laboratory of A. G. Dickson, Scripps Institute of Oceanography (SIO), USA (Dickson,

56

2003; 2010). Comparability and traceability of nutrient concentration measurements has been ensured

57

using CRMs provided by the National Metrology Institute of Japan (NMIJ) and SCOR-JAMSTEC and58

KANSO CRMs provided by the KANSO Co. Ltd. (Sato et al., 2010; Aoyama et al., 2012). For these59

community-accepted standards such as salinity standard solution, carbonate CRM, and nutrient CRMs,

60

continual monitoring and readily available documentation are essential to keep the consistency and long-61

term quality of those standards through studies such as batch to batch comparison studies of salinity

62

standard solution (Mantyla, 1987; Aoyama et al., 2002; Kawano et al., 2006), inter-laboratory

63

comparison exercises of carbonate system CRM (Bockmon and Dickson, 2015) and inter-laboratory

64

comparison exercises (Aoyama et al., 2006, 2007, 2008, 2012, 2016, 2018).

65
66

community and

It is also possible to use some standard instruments and high-quality data obtained byphysical/chemical measurements to calibrate raw data from sensors/instruments onboard.

67

Duplicate/replicate measurements may also be made on water samples for quality control and for

68

determination of the magnitude of reproducibility of the measurements. Multiple measurements of the69

same sample may also be made. The number of such measurements might be 7–9 or more. A good70

example to get comparability among the measurements at multiple stations is also to use deep-sea water71

as tracking standard instead of CRMs. In this case, only comparability can be ensured but can not be

72

ensured for SI traceability.

73

If CRMs or SI-traceable measurements/instruments were involved, there is a need to conduct further

74

data quality control to discover inconsistencies and other anomalies in the data as well as to perform75

data-cleansing activities (e.g., removing outliers, flagging data as questionable or bad) to improve the
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76data quality. Inconsistencies and outliers may occur for several reasons, including simple/complex

77

human errors, mechanical malfunctions of instruments/sensors, and communication problems between

78

sensors and the host computer.

79

After quality control is carried out via an unbroken chain of comparisons with standards, a control

80

chart, and duplicate measurements, the quality control of property-property characteristics described in81

this chapter may be performed during the onboard measurements and may be performed after a dataset82

that includes all parameters has been completed.

83

2-2. Pre- and post-cruise calibration of sensors and water sample measurements

84

Best practices for pre- and post-cruise calibration of conductivity-temperature-depth (CTD) systems

85

and underway measurements are the main part of the quality control procedures described in section 4.

86

For water sample measurements, the best practices for bottle salinity, oxygen concentrations,87

nutrient concentrations, carbonate system parameters, and chlorophyll a (Chl. a) concentrations are

88

described in section 5.

89
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3. Metadata report and access to data by Intergovernmental Oceanographic Commission (IOC)recommendations
3-1. Cruise Summary Reports and metadata of the cruise

94

A Cruise Summary Report (CSR) is used to provide metadata for scientists, data managers, and95

program managers who need information about measurements and samples collected at ocean, namely,

96

who has collected what, when, and where. Historically parameters were defined using the Report of97

Observations/Samples collected by Oceanographic Programmes (ROSCOP) parameter codes. The

98

ROSCOP was conceived by IOC/IODE in the late 1960s in order to provide a low level inventory for99

tracking oceanographic data collected on research vessels. The ROSCOP form was extensively revised100

in 1990, and was re-named the CSR. Most marine disciplines are represented in the CSR, including

101

physical, chemical, and biological oceanography, marine geology and geophysics, fisheries, marine

102

contaminants, and marine meteorology. Traditionally, it is the chief scientist's obligation to submit a103

CSR to his/her National Oceanographic Data Centre (NODC) within two to three weeks after the cruise

104(Rickards and Nast, IOC/IODE-XIX/ 12, 2007).

105

The CSR is intended to fill the gap between the first announcement of an oceanographic program106

and the eventual catalogue of data available to users. As timely inventories of data to ensure prompt

107

exchange, the CSR contains such information as ocean area where the investigation was carried out,

108

track chart of the cruise, person who holds the data, name and volume of the data written in the IOC's

109

CSR form.

110

Currently, the CSRs directory covers cruises from 1873 till today from more than 2.000 research

111

vessels: a total of nearly 58.000 cruises, in all European waters and global oceans. This also includes

112

historic CSRs from European countries that have been loaded from the ICES database from 1960

113

onwards.( https://www.seadatanet.org/Standards/Metadata-formats/CSR accessed on 19 March 2020)

114

In Japan, we can submit CSRs online to Japan Oceanographic Data Center (JODC) at

115

https://www.jodc.go.jp/jodcweb/aboutInfo_j.html (accessed on 19 March 2020).

116
117

In 2003, the IOC Oceanographic Data Exchange Policy (Appendix I) was established for the118

efficient acquisition, integration, and use of ocean observations gathered by the countries of the world

119

for a wide variety of purposes, including the prediction of weather and climate, operational forecasting120of the marine environment, the preservation of life, the mitigation of adverse anthropogenic impacts on

121

the marine and coastal environment, as well as for the advancement of scientific understanding that122

makes application of this information possible. For these purposes, an appropriate data report and123

metadata report are essential and recommended.

124

In the IOC Oceanographic Data Exchange Policy (Appendix I), data and metadata are defined as

125

follows:

126‘Data’ consist of oceanographic observation data, derived data, and gridded fields.
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127
128‘Metadata’1 are 'data about data'. They describe the content, quality, condition, and other characteristics
of data.

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____________________________________________________

150
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1
It is easy to find information on the source of "metadata": the word was formed by combining "data"with "meta-," which means "transcending" and is often used to describe a new but related discipline
designed to deal critically with the original one. "Meta-" was first used in that way in "metaphysics" andhas been extended to a number of other disciplines, giving us such words as "metapsychology" and"metamathematics." "Metadata" takes the "transcending" aspect a step further and applies it to theconcept of pure information instead of a discipline. "Metadata" is a fairly new word (it appeared in thelatter half of the 20th century), whereas "data" can be traced back to the middle of the 17th century. The
first known use of metadata was in 1983. (https://www.merriam-webster.com/dictionary/metadata
accessed on 2 November 2019).

159

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3-2. Metadata and examples of metadata of several cruises

161

In this section, we show various examples of metadata, simple cruise summary report, based on

162

ROSCOP coding system and update. We also show a form for GEOTRACES cruises by AORI and163

expanded version of metadata by JMA (Appendix II).

164

Metadata may contain as shown below (A Guide to Submitting CTD/Hydrographic/Tracer Data and165

Associated Documentation to the CLIVAR and Carbon Hydrographic Data Office,166

https://cchdo.github.io/hdo-assets/documentation/policies/CCHDO_DataSubmitGuide.pdf).

167

1.

Highlights

168

a.

Cruise designation (cruise name) (e.g., "AIS01" for Amery Ice Shelf 1) [or, for a repeated WOCE-

169

era section, the section designation(s), for example A11, IR04, etc. Include all sections covered on

170

cruise].

171b.

EXPOCODE. Each leg has a unique EXPOCODE.

172

c.

Chief scientist for each leg, including postal and electronic addresses.

173

d.

Ship name.

174

e.

Ports of call. Port(s) where cruise begins and ends plus any stops during the cruise.

175

f.

Cruise dates (Official ship's log date of departure & return, port to port, for each leg).

176
177

2.
a.

Cruise Summary Information
Written description of the survey's geographic boundaries.

178

b.

Cruise track showing each station with different symbols used to indicate station type.

179

b.

Total number of stations occupied for each section, broken down by type of station and parameters

180

sampled at each station.

181

c.

Detailed list of each parameter measured on the cruise.

182

d.

Floats and drifters deployed (type, identification number, location, and time).

183

e.

Moorings deployed or recovered (type, identification, location, and time).

184
185

3.
a.

List of Principal Investigators for All Measurements
Name (please spell out).

186

b.

Measurement responsibility.

187

c.

Institution or affiliation (abbreviations should be defined).

188

d.

Postal and electronic addresses.

189
190

4.
a.

Scientific Program and Methods
Narrative.

191

b.

Interlaboratory comparisons made (if any) or comparisons with previous cruise data.

192

c.

(Optional) Vertical sections along the ship's track showing the bottle depth distributions, and plots

193

of property vs. property relationships.

194

5.

Major Problems and Goals Not Achieved

195

6.

Other Incidents of Note

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196
197

7.
a.

List of Cruise ParticipantsName (please spell out).

198

b.

Responsibility on cruise.

199

c.

Institution or affiliation (abbreviations should be defined).

200

d.

postal and electronic addresses.

201
202

There are also applicable to add more information into CRS when the items added are appropriate.

203

An example of cruise summary report is shown below and a few examples are in appendix II.

204

Example of cruise summary report

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Reference No.
: 20090040
Ship Name: RYOFU MARU
Ship Type: Research Vessel
Cruise No./Name: 08-09
Cruise Period: 2008/09/24 to 2008/10/24
Responsible Laboratory :Global Environment and Marine Department, JMA
Chief Scientist(s): NAKANO,Toshiya (Leg 1) SAKURAI,Keizo (Leg 2)
General Ocean Area(s) : North Pacific Ocean
Geographic Coverage: 131
Project Name
: JCOMM(former IGOSS), WESTPAC, MARPOLMON
Coordinating Body
: IOC
Principal Investigators :A;MINATO.S.:
Global Environment and Marine Department JMA:B;HAYASHI.K.:
Global Environment and Marine Department JMA:C:Senior Scientific Officer: Seismological andVolcanological Department JMA:D;HIRATA.K.: Seismological and Volcanological Research
Department MRI
Objectives and Brief Narrative of Cruise:
A routine oceanographic observation (physical)
Recovery of Ocean Bottom Seismographs(JMA,MRI)
Maritime meteorological observations.
Moorings, Bottom Mounted Gear and Drifting Systems:
PI LAT.
LON.
DATATYPEDESCRIPTION
D 32-20.3 134-40.5 G90
Recovered:J07 3612m 2008/09/27
Summary of Measurements and Samples Taken:
PI
NO
UNITS DATATYPEDESCRIPTION
A
29
Stations D71
Current Profiler
A 1051NM H71
Surface measurements underway（T）
B
60
Times M06
Routine standard measurements

238
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4. Best practices of quality control procedures for sensors in the case of the MR15-05 cruise by

240

JAMSTEC and the RF16-06 cruise by the JMA

241Best practices for the main quality control procedures used for pre- and post-cruise calibration of a

242
243

CTD system and underway measurements are described herein.
Original cruise report of MR15-05 is available at244

http://www.godac.jamstec.go.jp/catalog/data/doc_catalog/media/MR15-05_leg1_all.pdf (accessed245

on 19 March 2020) and that of RF16-06 is available at https://cchdo.ucsd.edu/cruise/49UP20160703

246(accessed on 23 March 2020). In the following sections 4 and 5 we use many materials from the247

cruise reports and revised them to fit for this guideline.

248

4-1 Quality control and calibrations for sensors in the case of the MR15-05 cruise (JAMSTEC)

249

Overview of the CTD equipment is described in (4-1-1), and the CTD system is summarized in (4-250

1-2). Pre-cruise calibration for sensors is the first step of quality control of data that can be obtained251with sensors (4-1-3). Post-cruise calibration of sensors is the next step (4-1-4). Pre- and post-cruise252

calibration of the underway measurement system is also described in (4-1-5). Actual procedures are253

described in this chapter.

254

4-1-1. Summary of the CTD system used in this cruise

255

The CTD system was a SBE 911plus system (Sea-Bird Electronics, Inc., Bellevue, Washington,

256USA). The SBE 911plus system controls a 36-position SBE 32 Carousel Water Sampler. The Carousel

257

accepts 12-litre Niskin-X water sample bottles (General Oceanics, Inc., Miami, Florida, USA). The SBE

258

9plus was mounted horizontally on a 36-position carousel frame. SBE’s temperature (SBE 3) and259

conductivity (SBE 4) sensor modules were used with the SBE 911plus underwater unit. The pressure

260

sensor was mounted in the main housing of the underwater unit and was ported to outside through an

261

oil-filled plastic capillary tube. A modular unit of the underwater housing pump (SBE 5T) flushed water262

through the sensor tubing at a constant rate independent of the CTD’s motion, and the pumping rate

263

(3000 rpm) remained nearly constant over the entire input voltage range of 12–18 volts DC. Flow speed

264of the pumped water in the standard TC duct was about 2.4 m/s. Two sets of temperature and265

conductivity modules were used. An SBE dissolved oxygen sensor (SBE 43) was placed between the266

primary conductivity sensor and the pump module. Auxiliary sensors, a Deep Ocean Standards

267

Thermometer (SBE 35), an altimeter (PSA-916T; Teledyne Benthos, Inc., North Falmouth,

268

Massachusetts, USA), and an oxygen optode sensor (RINKO-III; JFE Advantech Co., Ltd, Kobe Hyogo,

269

Japan) were also used with the SBE 9plus underwater unit. To minimize rotation of the CTD package,270

a heavy stainless-steel frame (total weight of the CTD package without seawater in the bottles was about271

1000 kg) was used with an aluminium plate (54 × 90 cm). To minimize attitude motion of the CTD

272

package (rotation, pitching, and rolling) and twist of the armoured cable, a slip ring swivel was inserted

273

between the armoured cable and the CTD package (Uchida et al., 2018).

274

4-1-2. Pre-cruise calibration of sensors
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275

i. Pressure

276

The Paroscientific series 4000 Digiquartz high-pressure transducer (Model 415K: Paroscientific,

277

Inc., Redmond, Washington, USA) uses a quartz crystal resonator, whose frequency of oscillation varies

278

with pressure-induced stress. The resolution is 0.01 parts per million of full scale over the absolute279

pressure range of 0 to 15,000 psia (0 to 10,332 dbar). Also, a quartz crystal temperature signal was used280

to compensate for a wide range of temperature changes at the time of an observation. The pressure281

sensor had a nominal accuracy of 0.015% FS (1.5 dbar), typical stability of 0.0015% FS/month (0.15282

dbar/month), and resolution of 0.001% FS (0.1 dbar). Because the pressure sensor measures absolute283

pressure, it inherently includes atmospheric pressure (about 14.7 psi). SEASOFT subtracts 14.7 psi from284

the computed pressure automatically.

285

Pre-cruise sensor calibrations for linearization were performed at SBE, Inc. The temporal drift of286

the pressure sensor was adjusted by periodic recertification corrections against a dead-weight piston

287

gauge (Model 480DA, S/N 23906; Piston unit, S/N 079K; Weight set, S/N 3070; Bundenberg Gauge

288

Co. Ltd., Irlam, Manchester, UK). The corrections were performed at JAMSTEC, Yokosuka, Kanagawa,

289

Japan by Marine Works Japan, Ltd. (MWJ), Yokohama, Kanagawa, Japan, usually once per year to290

monitor sensor temporal drift and linearity.

291

S/N 0786, 13 July 2015

292

slope = 0.99980434

293

offset = –0.13013

294

ii. Temperature (SBE 3)

295

The temperature-sensing element was a glass-coated thermistor bead in a stainless-steel tube. This

296

sensor provided pressure-free measurements at depths up to 10,500 (6800) m in its titanium (aluminium)

297

housing. The SBE 3 thermometer has a nominal accuracy of 1 mK, typical stability of 0.2 mK/month,298

and resolution of 0.2 mK at 24 samples per second. The premium temperature sensor, SBE 3plus, is a299

more rigorously tested and calibrated version of the standard temperature sensor (SBE 3).

300

Pre-cruise sensor calibrations were performed at SBE, Inc.

301

S/N 03P4815, 16 April 2015

302

S/N 031525, 28 July 2015

303

Pressure sensitivities of the SBE 3s were corrected in accord with the method of Uchida et al.

304(2007), for the following sensor:

305

S/N 03P4815, –3.4597 × 10–7 (K/dbar)

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306

iii. Conductivity (SBE 4)

307

The flow-through conductivity sensing element was a glass tube (cell) with three platinum electrodes308

to provide in-situ measurements at depths up to 10,500 (6800) m in a titanium (aluminium) housing.

309

The SBE 4 has a nominal accuracy of 0.0003 S/m, typical stability of 0.0003 S/m/month, and resolution

310

of 0.00004 S/m at 24 samples per second. The conductivity cells have been replaced to newer style cells

311

for deep ocean measurements.

312

Pre-cruise sensor calibrations were performed at SBE, Inc.

313

S/N 042435, 1 May 2015314

S/N 042854, 1 May 2014315

The value of the conductivity at a salinity of 35, temperature of 15°C (IPTS-68), and pressure of316

0 dbar was 4.2914 S/m.

317

iv. Oxygen (SBE 43)

318

The SBE 43 oxygen sensor uses a Clark polarographic element to provide in-situ measurements at

319

depths up to 7000 m. The range for dissolved oxygen is 120% of surface saturation in all natural waters;

320

nominal accuracy is 2% of saturation; and typical stability is 2% per 1000 hours.

321
322

Pre-cruise sensor calibration was performed at SBE, Inc.
S/N 430330, 10 May 2015323

Note: Factory/manufacturer's calibrations of the conductivity and oxygen sensors will not provide

324

adequate quality data for WOCE-like work, and that application of data from analyses of water

325

samples at sea will be required as described in section 5.

326

v. Deep-Ocean Standard Thermometer327

The deep-ocean standard thermometer (SBE 35) was an accurate, ocean-range temperature sensor

328

that could be standardized against the Triple Point of Water and Gallium Melt Point cells and was also329

capable of measuring temperature in the ocean to depths of 6800 m. The SBE 35 was used to calibrate330

the SBE 3 temperature sensors in situ (Uchida et al., 2007).

331
332

Pre-cruise sensor linearization was performed at SBE, Inc.
S/N 0022, 4 March 2009333

The SBE 35 was then certified by measurements in thermodynamic fixed-point cells of the TPW

334(0.01°C) and GaMP (29.7646°C). The slow time drift of the SBE 35 was adjusted by periodic

335

recertification corrections. Pre-cruise sensor calibration was performed at SBE, Inc. Since 2014, fixed-

336

point cells traceable to NIST temperature standards have been directly used in the manufacturer’s

337

calibration of the SBE 35 (Uchida et al., 2015a).
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338

S/N 0022, 4 February 2015 (slope and offset correction)

339

Slope = 1.000007

340

Offset = 0.000246

341

The time required per sample = 1.1 × NCYCLES + 2.7 seconds. The time of 1.1 seconds is the total

342

time per acquisition cycle. NCYCLES is the number of acquisition cycles per sample and was set to 4.

343

A time of 2.7 seconds is required for converting the measured values to temperature and storing the344

average in EEPROM.

345

vi. Oxygen optode (RINKO)

346
347

The RINKO (JFE Alec Co., Ltd.) sensor, a fast-response optical oxygen sensor, takes advantage ofthe ability of selected substances to act as dynamic fluorescence quenchers. The RINKO model III is348

designed for use with a CTD system that will accept an auxiliary analog sensor and is designed to operate349

down to 7000 m.

350

Data from the RINKO can be corrected for time-dependent, pressure-induced effects by means of351

the same method as that developed for the SBE 43 (Edwards et al., 2010). The calibration coefficients,352

H1 (amplitude of hysteresis correction), H2 (curvature function for hysteresis), and H3 (time constant353

for hysteresis) were determined empirically as follows:354

H1 = 0.0055 (for S/N 0024)

355

H2 = 5000

356

dbar H3 = 2000 seconds

357
358
359

The outputs from RINKO are the raw phase-shift data. The RINKO can be calibrated by the modified
Stern-Volmer equation slightly modified from a method by Uchida et al. (2010):
O2 (µmol/l) = [(V0 / V)E – 1] / Ksv

360

where V is voltage, V0 is the voltage in the absence of oxygen, and Ksv is the Stern-Volmer constant.

361

The coefficient E corrects for nonlinearity of the Stern-Volmer equation. The V0 and the Ksv are assumed362

functions of temperature as follows:363

Ksv = C0 + C1 × T + C2 × T2

364

V0 = 1 + C3 × T

365

V = C4 + C5 × Vb

366

where T is the CTD temperature (°C) and Vb is the raw output (volts). V0 and V are normalized by the367

output in the absence of oxygen at 0°C.

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368

The oxygen concentration is calculated using accurate temperature data from the CTD temperature369

sensor instead of temperature data from the RINKO. The pressure-compensated oxygen concentration

370

O2c can be calculated as follows.

371

O2c = O2 (1 + Cp p / 1000)

372

where p is the CTD pressure (dbar) and Cp is the compensation coefficient. Because the sensing foil of373

the optode is permeable to only gas and not to water, the optode oxygen must be corrected for salinity.

374

The salinity-compensated oxygen can be calculated by multiplying O2c by a factor to correct for the375

effect of salt on the oxygen solubility (Garcia and Gordon, 1992).

376

Pre-cruise sensor calibrations were performed at RCGC/JAMSTEC.

377

S/N 0024, 10 May 2015

378

4-1-3. Post-cruise calibration of CTD sensors

379
380

i. Pressure

381

ship deck. For best results, the Paroscientific sensor was powered on for at least 20 minutes before the382

operation. In order to get the calibration data for the pre- and post-cast pressure sensor drift, the CTD

383

deck pressure was averaged over the first and last minute, respectively. Then the atmospheric pressure384

deviation from standard atmospheric pressure (14.7 psi) was subtracted from the CTD deck pressure to385

check for temporal drift of the pressure sensor. Atmospheric pressure was measured at the captain deck386

(20 m above the baseline) and at one-minute intervals.

The CTD pressure sensor offset during the cruise was estimated from the pressure readings on the387

The pre- and post-cast deck pressure data revealed a temperature dependence of the pressure sensor

388(Figure 4.1.1). To correct for the temperature dependence, the manufacturer’s calibration coefficients389

were modified slightly on board as follows:390

T1 = 29.88499

391

T2 = –2.565740 × 10–4

392

T3 = 4.799030 × 10–6

393

Offset = 0.0394

Figure 4.1.2 shows a time series of the CTD deck pressure. The CTD pressure sensor offset was

395

estimated from the deck pressure. The mean of the pre- and the post-cast data over the whole period

396

provided an estimation of the pressure sensor offset (–0.01 dbar) from the pre-cruise calibration. A post-397

cruise correction of the pressure data was not deemed necessary for the pressure sensor.

398
399

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400
401
402

Figure 4.1.1 Pre- and post-cast CTD deck pressure. Atmospheric pressure deviation from a standard

403

atmospheric pressure was subtracted from the CTD deck pressure. Black dots show the original data,404

and red dots show the data corrected for the temperature dependence of the sensor.

405

406
407

Figure 4.1.2 Time series of the CTD deck pressure. Atmospheric pressure deviation (magenta dots) from408

a standard atmospheric pressure was subtracted from the CTD deck pressure. Blue and green dots

409

indicate pre- and post-cast deck pressures, respectively. Red dots indicate averages of the pre- and the410

post-cast deck pressures.
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411

ii. Temperature

412
413
414
415
416
417

The CTD temperature sensors (SBE 3) were calibrated with the SBE 35 in accord with the methodof Uchida et al. (2007) on the assumption that discrepancies between SBE 3 and SBE 35 data were due
to pressure sensitivity, the viscous heating effect, and temporal drift of the SBE 3.
Post-cruise sensor calibration of the SBE 35 was performed in 2016 at SBE, Inc.

418
419
420
421
422

The CTD temperature data were preliminarily calibrated as follows:
Calibrated temperature = T – (c0 × P + c1 × t + c2 )where T is the CTD temperature in °C, P is pressure in dbar, t is time in days from the pre-cruise
calibration date of the CTD temperature, and c0, c1, and c2 are calibration coefficients. The coefficientswere determined using the data for depths corresponding to pressures greater than 1950 dbar. The
coefficient c1 was set to zero for this cruise.

423
424
425
426
427
428

The primary temperature data were used for the post-cruise calibration. The secondary temperature
sensor was also calibrated and used instead of the primary temperature data when the quality of the
primary temperature data was bad. The calibration coefficients are listed in Table 4.1.1. The results ofthe post-cruise calibration for the CTD temperature are summarized in Table 4.1.2 and are shown in
Figure 4.1.3.

429

Table 4.1.1 Calibration coefficients for the CTD temperature sensors.

430--------------------------------------------------------------------------------------------------------------

431
432
433
434
435

Serial number

c0 (°C/dbar)

c1 (°C/day)c2 (°C)------------------------------------------------------------------------------------------------------------------------3P4815–4.79962 × 10–8

0.0

–0.0007-------------------------------------------------------------------------------------------------------------------------

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436

Table 4.1.2 Difference between the CTD temperature and the SBE 35 temperature after the post-cruise

437

calibration. Mean and standard deviation (Sdev) were calculated for data collected at pressures below

438

and above 1950 dbar. Number is the number of data used in the calculations.
-----------------------------------------------------------------------------------------------------------------------------Serial number

Pressure ≥ 1950 dbar
Number

Mean

Sdev

(mK)

(mK)

Pressure < 1950 dbar
Number

Mean

Sdev

(mK)

(mK)

-----------------------------------------------------------------------------------------------------------------------------3P4815

467

0.0

0.2

854

–0.0

6.8

------------------------------------------------------------------------------------------------------------------------------

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Figure 4.1.3 Difference between the CTD temperature (primary) and the SBE 35 temperature. Blue andred dots indicate before and after the post-cruise calibration using the SBE 35 data, respectively. Lower
two panels show histograms of the differences after the calibration.

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iii. Salinity

The discrepancy between the CTD conductivity and the conductivity calculated from the bottle
salinity data with the CTD temperature and pressure data was considered to be a function of conductivity,pressure, and time. The CTD conductivity was calibrated as follows:
Calibrated conductivity = c0 × C + c1 × P + c2 × C × P + c3 × C2 + c4 × t + c5
where C is CTD conductivity in S/m, P is pressure in dbar, t is time in days, and c0, c1, c2, c3, c4, andc5 are calibration coefficients. The best fit sets of coefficients were determined by a least squares
technique to minimize the deviations from the conductivities calculated from the bottle salinity data.
The coefficient c4 was set to zero for this cruise.
The primary conductivity data created by the software module ROSSUM were used after the postcruise calibration for the temperature data. Table 4.1.3 lists the calibration coefficients. The results ofthe post-cruise calibration for the CTD salinity are summarized in Table 4.1.4 and shown in Figure
4.1.4.
Table 4.1.3 Calibration coefficients for the CTD conductivity sensors.
-----------------------------------------------------------------------------------------------------------------------------Serial
number

c0

c1

c2

c3

c4

S/(m dbar)

1/dbar1/(S/m)S/m-----------------------------------------------------------------------------------------------------------------------------042435–1.51687 × 10–4 1.09232 × 10–7 –3.67361 × 10–8 4.72348 × 10–12 5.09192 × 10–4------------------------------------------------------------------------------------------------------------------------------

Table 4.1.4 Difference between the CTD salinity and the bottle salinity after the post-cruise calibration.
Mean and standard deviation (Sdev) (in 10–3) are calculated for the data collected from pressures below
and above 1950 dbar. Number is the number of data used.
-------------------------------------------------------------------------------------------------------------------------------Serial
Pressure ≥ 1950 dbar
Pressure < 1950 dbar
numberNumber Mean Sdev
Number Mean Sdev------------------------------------------------------------------------------------------------------------------------------042435
493–0.0 0.4
861
0.2
4.5
-------------------------------------------------------------------------------------------------------------------------------

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Figure 4.1.4 Difference between the CTD salinity (primary) and the bottle salinity. Blue and red dots
indicate before and after the post-cruise calibration, respectively. Lower two panels show histogramsof the differences after the calibration.

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iv.

OxygenThe RINKO oxygen optode (S/N 0024) was calibrated and used instead of the CTD oxygen data,
because the RINKO has a fast response time. The pressure-hysteresis corrected RINKO data were
calibrated by the modified Stern-Volmer equation, basically in accord with Uchida et al. (2010) withslight modification:[O2] (µmol/l) = [(V0 / V)1.5 – 1] / Ksv
andKsv = C0 + C1 × T + C2 × T2
V0 = 1 + C3 × T
V = C4 + C5 × Vb + C6 × t + C7 × t × Vb
where Vb is the RINKO output (voltage), V0 is the voltage in the absence of oxygen, T is temperature
in °C, and t is the exciting time (days) integrated from the first CTD cast. Temporal drift of the RINKO
output was corrected. The calibration coefficients were determined by minimizing the sum of theabsolute deviations and also include weight from the bottle oxygen data. The revised quasi-Newton
method (DMINF1) was used to determine the sets of coefficients.
The post-cruise calibrated temperature and salinity data were used for the calibration. Table 4.1.5
lists the calibration coefficients. The results of the post-cruise calibration for the RINKO oxygen aresummarized in Table 4.1.6 and are shown in Figure 4.1.5.
Table 4.1.5 Calibration coefficients for the RINKO oxygen sensors.
---------------------------------------------------------Coefficient

S/N 0024---------------------------------------------------------c0
5.56160 × 10–3
c1
2.16834 × 10–4
c2
2.72251 × 10–6
c3
–1.03972 × 10–3
c4
–2.07308 × 10–2
c5
0.326691
c6
1.52604 × 10–4
c7
1.29920 × 10–5
Cp
0.015----------------------------------------------------------

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Table 4.1.6 Difference between the RINKO oxygen and the bottle oxygen after the post-cruise
calibration. Mean and standard deviation (Sdev) are calculated for the data collected from below andabove a pressure of 1950 dbar. Number is the number of data used.
-------------------------------------------------------------------------------------------------------------------Serial number

Pressure ≥ 1950 dbar

Pressure < 1950 dbar

NumberMean Sdev
Number Mean Sdev(µmol/kg)(µmol/kg)------------------------------------------------------------------------------------------------------------------0024

502

0.11

0.39

859

0.02

0.57

-------------------------------------------------------------------------------------------------------------------

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Figure 4.1.5 Difference between the CTD oxygen and the bottle oxygen. Blue and red dots indicate
before and after the post-cruise calibration, respectively. Lower two panels show histograms of thedifferences after the calibration.

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4-1-5. Underway measurements with sensors(1) Materials and methods
The Continuous Sea Surface Water Monitoring System (Marine Works Japan Co, Ltd.) has sevensensors and automatically measures salinity, temperature, dissolved oxygen, fluorescence, and turbidity
in sea surface water every minute. The system was in the sea-surface-monitoring laboratory with anintake on the bottom of the ship and was connected to a shipboard LAN system. Measured data alongwith time and location of the ship are displayed on a monitor and stored in a desktop computer. Sea
surface water was continuously pumped up to the laboratory from a depth of about 5 m and routed tothe system through a vinyl-chloride pipe. One thermometer was located just before the sea water pumpin the bottom of the ship. The flow rate of the surface seawater was maintained at about 1.2 L/min.
Periods of measurement, maintenance, and problems are listed in Table 4.1.7.
Software and sensors used in this system are listed below.
i. Software
Seamoni-kun Ver.1.50
ii. Sensors
Temperature and conductivity sensor
Model:

SBE 45, Sea-Bird Electronics, Inc.

Serial number:

4552788-0264

Pre-cruise calibration:

30 August 2014, Sea-Bird Electronics, Inc.

Bottom of ship thermometer
Model:

SBE 38, Sea-Bird Electronics, Inc.

Serial number:

3852788-0457

Pre-cruise calibration:

31 October 2014, Sea-Bird Electronics, Inc.

Dissolved oxygen sensor
Model:

RINKO-II, JFE Adantech Co. Ltd.

Serial number:0013

Pre-cruise calibration:

10 May 2015, JAMSTEC

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Table 4.1.7. Log of events of the Continuous Sea-Surface-Water-Monitoring System operation.

System date

System time Event

[UTC]

[UTC]

2015/12/23

19:00

2015/12/24
2015/12/29
2015/12/29
2016/1/5
2016/1/5
2016/1/5
2016/1/11
2016/1/17
2016/1/23

Logging for leg 1 start
Flow rate for RINKO and05:23–06:07 optode small, though bothdata seem to be normal.
Logging stop for C3/filter
10:11
cleaning
11:23
Logging restart
Logging stop for C3/filter
11:27
cleaning
13:05
Logging restart
13:05–13:25 Optode unstable.
22:00
Logging for leg 1 end
13:35
Logging for leg 2 start
6:23
Logging for leg 2 end(2) Pre-cruise calibration
Pre-cruise sensor calibrations for the SBE 45 and SBE 38 were performed at Sea-Bird Electronics,
Inc.
Pre-cruise sensor calibrations for the oxygen sensors were performed at JAMSTEC. The oxygen
sensors were immersed in freshwater in a 1-L semi-closed glass vessel, which was immersed in atemperature-controlled water bath. Temperature of the water bath was set to 1, 10, 20, or 29ºC.
Temperature of the freshwater in the vessel was measured by a thermistor thermometer (expanded
uncertainty less than 0.01ºC, ARO-PR, JFE Advantech, Co., Ltd.). At each temperature, the freshwaterin the vessel was bubbled with standard gases (4, 10, 17, or 25% oxygen in an oxygen-nitrogen mixture,
whose relative expanded uncertainty was 0.5%) for more than 30 minutes to ensure saturation. Absolutepressure of the vessel headspace was measured by a reference quartz crystal barometer (expanded
uncertainty 0.01% of reading) and ranged from about 1040 to 1070 hPa. The data were averaged overthree minutes at each calibration point (a matrix of 24 points). As a reference, the oxygen concentrationof the freshwater in the calibration vessel was calculated from the oxygen concentration of the gases,
temperature, and absolute pressure at the water depth (about 8 cm) of the sensor’s sensing foil as follows:
O2 (µmol/L) = {1000 × c(T) × (Ap – pH2O)} / {C × 22.3916 × (1013.25 – pH2O)}
where c(T) is the oxygen solubility, Ap is absolute pressure (hPa), pH2O is the water vapour pressure(hPa), and C is the mole fraction of oxygen in the gas (C = 0.20946 for air).
The RINKO was calibrated by the modified Stern-Volmer equation with slight modification from themethod of Uchida et al. (2010):
O2 ( µmol/L) = [(V0 / V)E – 1] / Ksv
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where V is the raw phase difference, V0 is the raw phase difference in the absence of oxygen, and Ksv
is the Stern-Volmer constant. The coefficient E corrects for nonlinearity of the Stern-Volmer equation.
The coefficients V0 and the Ksv are assumed to be functions of temperature as follows.
Ksv = C0 + C1 × T + C2 × T2
V0 = 1 + C3 × T
V = C4 + C5 × Vb
where T is the CTD temperature (°C), and Vb is raw output of the sensor. The oxygen concentration
was calculated using accurate temperature data from the SBE 45 instead of temperature data from the
RINKO. The calibration coefficients were as follows:
C0 = 5.048509438066593 × 10−3
C1 = 2.212851808960770 × 10−4
C2 = 3.735982971782336 × 10−6
C3 = −7.847113805097885 × 10−4
C4 = 3.011495646664952 × 10−2
C5 = 0.1926948014214438
E = 1.5(3) Data processing and post-cruise calibration
Data from the Continuous Sea Surface Water Monitoring System were obtained at 1-minute intervals.
Data from the nitrate sensor were obtained at 2-minute intervals and linearly interpolated at 1-minuteintervals.
These data were processed as follows. Spikes in the temperature and salinity data were removed
using a median filter with a window of 3 scans (3 minutes) when the difference between the original
data and the median filtered data exceeded 0.1ºC for temperature and 0.5 for salinity. Data gaps werelinearly interpolated when the gap was ≤13 minutes. Raw data from the RINKO oxygen sensor were
low-pass filtered using a Hamming filter with a window of 15 scans (15 minutes).
Salinity (g/kg) and dissolved oxygen (O2 [µmol/kg]) data were corrected using the data from the water
samples. Corrected salinity (Scor) and dissolved oxygen (Ocor) were calculated from the following
equations
Scor = c0 + c1 S + c2 t
Ocor [μmol/kg] = c0 + c1 O + c2 T + c3 t
where S is salinity, t is days from a reference time (2015/12/23 19:00 [UTC]), and T is temperature inºC. The best fit sets of calibration coefficients (c0−c3) were determined by a least squares technique tominimize the deviations from the water-sample data. Table 4.1.8 lists the calibration coefficients.
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Comparisons between the Continuous Sea Surface Water Monitoring System data and sampled water
data are shown in Figures 4.1.6 and 4.1.7.
Table 4.1.8. Calibration coefficients for salinity and dissolved oxygen.
------------------------------------------------------------------------------------------------------------------------------------------c1c2
c3
Parameterc0------------------------------------------------------------------------------------------------------------------------------------------0.9976929
1.379279 × 10−4
Salinity
9.031385 × 10−2
Dissolved oxygen
9.359068
0.9362957
0.0-8.934918 × 10−3

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Figure 4.1.6. Comparison between TSG salinity (red: before correction, green: after correction) andsampled salinity.

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Figure 4.1.7. Comparison between TSG oxygen (red: before correction, green: after correction) andsampled oxygen.

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4-2. Quality control and calibrations of sensors in the case of the RF16-06 cruise (JMA)
4-2-1.

CTD O2 measurement system

Deck unit

Serial number

StationSBE 11plus (SBE)

0683

RF5802 – 5893

Underwater unit

Serial number

StationSBE 9plus (SBE)35560 (Pressure: 0764)

RF5802 – 5893

Temperature

Serial number

StationSBE 3plus (SBE)4321 (primary)

RF5802 – 5893

4437 (secondary)

RF5802 – 5893

SBE 35 (SBE)

0062

RF5802 – 5893

Conductivity

Serial number

Station2842 (primary)

RF5802 – 5893

4316 (secondary)

RF5802 – 5893

Serial number

Station7752 (primary)

RF5802 – 5893

5501 (secondary)

RF5802 – 5893

Serial number

Station026 (foil number:144601B)

RF5802 – 5893

008 (foil numner:141304B)

RF5802 – 5893

Water sampler (36 position)

Serial number

StationSBE 32 (SBE)

0734

RF5802 – 5893

Altimeter

Serial number

Station

PSA-916D (TB)

68640

RF5802 – 5893

SBE 4C (SBE)Pump
SBE 5T (SBE)
OxygenRINKO III (JFE)

Water sampling bottle

StationNiskin Bottle (GO)RF5802 – 5893

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4-2-2. Pre-cruise calibrationa. Pressure

S/N 0764, 29 Sep. 2015
c1=

–4.318853 × 104

t1=

3.005385 × 101

c2=–4.853949 × 10–1

t2=

–4.407111 × 10–4

c3=

1.294200 × 10–2

t3=

4.098190 × 10–6

d1=

3.706500 × 10–2

t4=

1.662250 × 10–9d2=

0.000000

t5=

0.000000

Formulae:c = c1 + c 2 × U + c3 × U 2
d = d1 + d 2 × U
t 0 = t1 + t 2 × U + t 3 × U 2 + t 4 × U 3 + t 5 × U 4
U (degrees Celsius) = M × (12-bit pressure temperature compensation word) + B
U: temperature in degrees Celsius
S/N 0764 coefficients in SEASOFT (configuration sheet dated on 29 Sep. 2015)
M = 1.289080×10–2, B = –8.282450
Finally, pressure is computed as{}P( psi ) = c × (1 − t 02 t 2 ) × 1 − d × (1 − t 02 t 2 )t: pressure period (μsec)
The drift–corrected pressure is computed as

Drift corrected pressure(dbar ) = slope × (computed pressure in dbar )＋offset
Slope = 0.999960, Offset = 6.40070

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b. Temperature (ITS-90): SBE 3plus
S/N 4321(primary), 06 May 2016g=

4.39129096 × 10–3

j=1.99204111 × 10–6h=6.47616701 × 10–4

f0=

1000.000i=

2.32416022 × 10–5

S/N 4437(secondary), 06 May 2016g=

4.33413999 × 10–3

j=1.83139021 × 10–6

h=6.37288356 × 10–4

f0=

1000.000i=

2.11324800 × 10–5

Formula:Temperature( ITS − 90) =g + h × ln( f 01− 273.15f ) + i × ln 2 ( f 0 f ) + j × ln 3 ( f 0 f )f : Instrument freq.[Hz]c. Deep Ocean Standards Thermometer Temperature (ITS-90): SBE 35
S/N 0062, 25 Mar. 2006
a0=

4.41977256 × 10–3

a3=

–1.01508095 × 10–5

a1=

–1.19652517 × 10–3

a4=

2.17345047 × 10–7

a2=

1.82077469 × 10–4

Formula:Linearized temperature( ITS－90) = 1 /{a 0 + a1 × ln 2 (n) + a3 × ln 3 (n) + a 4 × ln 4 (n)}－273.15
n: instrument output
The slow time drift of the SBE 35
S/N 0062, 11 Apr. 2016 (2nd step: fixed point calibration)
Slope = 1.000010, Offset = –0.001106
Formula:Temperature( ITS－90) = slope × ( Linearized temperature)＋offset

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d. Conductivity: SBE 4C

g
h
i

=
=
=

S/N 2842(primary), 10 May 2016
(new cell preventing a stress concentration)j= 2.70164000 × 10–5
–1.01280649 × 101
1.38834906
CPcor = –9.57 × 10–8
CTcor = 3.25 × 10–6
5.51057500 × 10–4

g
h
i

=
=
=

S/N 4316(secondary), 16 Oct. 2015–9.87076057
j= 2.45401575 × 10–4
1.29126815
CPcor = –9.57 × 10–8
–3
CTcor = 3.25 × 10–6
–2.63568263 × 10

Conductivity of a fluid in the cell is expressed as:(

C ( S / m) = g + h × f 2 + i × f 3 + j × f 4) {10 × (1 + CT × t + CP × p )}
cor

cor

f: instrument frequency (kHz)t: water temperature (degrees Celsius)
p: water pressure (dbar).

e. Oxygen (RINKO III)The RINKO III (JFE Advantech Co., Ltd., Japan) sensor is based on the ability of a selected
substance to act as a dynamic fluorescence quencher. The RINKO III model is designed to be usedwith a CTD system that accepts an auxiliary analog sensor, and it is designed to operate down to 7000
m. The RINKO III output is expressed in voltage from 0 to 5 V.
4-2-3. Quality control and data correction during the cruisea. Temporal change of deck pressure
The post-cruise drift-corrected pressure was computed as follows:

Drift corrected pressure(dbar ) = slope × (computed pressure in dbar )＋offset
S/N 0764, 08 Nov. 2016
Slope = 0.999960，Offset = 8.19890

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Figure 4.2.1 Time series of the CTD deck pressure. Red line indicates atmospheric pressure anomaly.
Blue line and dots indicate pre-cast deck pressure and average.

b. Temperature sensor (SBE 3plus)
The practical corrections for the CTD temperature data can be made by using a SBE 35 andcorrecting the SBE 3plus so that it agrees with the SBE 35 (McTaggart et al., 2010; Uchida et al., 2007).
CTD temperature is corrected as follows:

Corrected temperature = T − (c0 + c1 × P + c2 × P 2 )T: CTD temperature (degrees Celsius), P: pressure (dbar), and c0, c1, c2: coefficients

Table 4.2.1. Temperature correction summary (pressure ≥ 2000 dbar). (Bold: accepted sensor)c 1 (K/dbar)c 0 (K)

S/N

Num

4321

707

2.3323330 × 10

4321

327

3.6978161 × 10 –4–6.5882684 × 10 –8

4437

707

7.8778043 × 10 –4

2.0218373 × 10 –7

4437

327

–4

1.9079349 × 10 –7–4

6.9565103 × 10

1.1254432 × 10

–7

C 2 (K/dbar 2 )Stations

0.0000000

RF5802 – 5860

3.1757133 × 10 – RF5861 – 5892
0.0000000
RF5802 – 5860
0.0000000

RF5861 – 5892

Table 4.2.2. Temperature correction summary for S/N 4321.
Pressure < 2000 dbar
Stations

Num

Pressure ≥ 2000 dbar

Average

Std

(K)

(K)

Num

Average

Std

(K)

(K)

RF5802 – 58601326

–0.0004

0.0116707

00.0003

RF5861 – 5892

793

–0.0004

0.0112327

00.0002

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Table 4.2.3. Temperature correction summary for S/N 4437.
Pressure < 2000 dbar
Stations

Num

Pressure ≥ 2000 dbar

Average

Std

(K)

(K)

Num

Average

Std

(K)

(K)

RF5802 – 58601326

–0.00020.0138707

00.0002

RF5861 – 5892

793

–0.0036

0.0226327

00.0002

Figure 4.2.2. Difference between the CTD temperature (S/N 4437) and the Deep Ocean Standards
thermometer (SBE 35) on Leg 1. Blue and red dots indicate before and after the correction using SBE
35 data, respectively. Lower two panels show histograms of the differences after correction.
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Figure 4.2.3. Difference between the CTD temperature (S/N 4437) and the Deep Ocean Standards
thermometer (SBE 35) on Leg 2. Blue and red dots indicate before and after the correction using SBE
35 data, respectively. Lower two panels show histograms of the differences after correction.

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c. Conductivity sensor (SBE 4C)
The practical corrections for CTD conductivity data can be made by using bottle salinity data tocorrect the SBE 4C to agree with measured conductivity (McTaggart et al., 2010).
CTD conductivity was corrected as follows:
I

J

i =0

j =1

Corrected Conductivity = C − (∑ ci × C i + ∑ p j × P j )C: CTD conductivity, ci and pj: calibration coefficients
i, j: determined by use of the AIC (Akaike, 1974). In accord with McTaggart et al. (2010), themaximum of I and J were 2.
Table 4.2.4. Conductivity correction coefficient summary. (Bold: accepted sensor)
c1c 2 (m/S)

p 1 (S/m/dbar)–40.00000.00003.3558 × 10

–52.4453 × 10

–40.00001.0413 × 10

–45.9318 × 10–5

0.00001.2606 × 10

–55.7968 × 10

–50.00001.0559 × 10

S/N

Num

c 0 (S/m)

2842

2118

2.5716 × 10

2842

1130

–6.0610 × 10

4316

2116

–1.1809 × 10

4316

1130

–5.9158 × 10

p 2 (S/m/dbar 2 )Stations–8–2.7075 × 10–13 RF5802 – 5860–7

–1.0413 × 10

–7

–1.0385 × 10–11 RF5802 – 5860

–7

–6.2355 × 10

–11 RF5861 – 5892

–12

RF5861 – 5892

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Table 4.2.5. Conductivity correction and salinity correction summary for S/N 2842.
Stations

Conductivity
Num

Average(S/m)

Salinity
Std
(S/m)

Num

Average

Std

Pressure < 1900 dbar
RF5802 – 5860

1314

0.00000.00031314

0.00000.0022

RF5861 – 5892

754

0.00000.0003754

0.00000.0022

RF5802 – 5860804

0.00000.0000804

0.00000.0005

RF5861 – 5892

376

0.00000.0001376

0.00000.0006

Pressure ≥ 1900 dbar

Table 4.2.6. Conductivity correction and salinity correction summary for S/N 4316.
Stations

Conductivity
Num

Average(S/m)

Salinity
Std
(S/m)

Num

Average

Std

Pressure < 1900 dbar
RF5802 – 5860

1306

0.00000.00021306

00.0019RF5861 – 5892

766

0.00000.0003766

00.0024

RF5802 – 5860

810

0.00000810

0.00000.0004

RF5861 – 5892

364

0.00000364

0.00000.0005Pressure ≥ 1900 dbar

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Figure 4.2.4. Difference between the CTD conductivity (S/N 4316) and the bottle conductivity on Leg
1. Blue and red dots indicate before and after the calibration using bottle data, respectively. Lower twopanels show histograms of the differences before and after calibration.

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Figure 4.2.5. Difference between the CTD conductivity (S/N 4316) and the bottle conductivity on Leg
2. Blue and red dots indicate before and after the calibration using bottle data, respectively. Lower twopanels show histograms of the differences before and after calibration.

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d. Oxygen sensor (RINKO III)The CTD oxygen concentration was calculated using the RINKO III output (voltage) with the SternVolmer equation in accord with the method of Uchida et al. (2008) and Uchida et al. (2010). The pressure
hysteresis for the RINKO III output (voltage) was corrected in accord with Sea-Bird Electronics (2009)
and Uchida et al. (2010). The equations were as follows:

𝑃𝑃0 = 1.0 + 𝑐𝑐4 × 𝑡𝑡

𝑃𝑃𝑐𝑐 = 𝑐𝑐5 + 𝑐𝑐6 × 𝑣𝑣 + 𝑐𝑐7 × 𝑇𝑇 + 𝑐𝑐8 × 𝑇𝑇 × 𝑣𝑣
𝐾𝐾𝑠𝑠𝑠𝑠 = 𝑐𝑐1 + 𝑐𝑐2 × 𝑡𝑡 + 𝑐𝑐3 × 𝑡𝑡 2

𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 = (1.0 + 𝑐𝑐9 × 𝑃𝑃⁄1000)1⁄3[O2 ] = Osat
× {(𝑃𝑃0 ⁄𝑃𝑃𝑐𝑐 − 1.0)⁄𝐾𝐾𝑠𝑠𝑠𝑠 × 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐}
2

P: pressure (dbar), t: potential temperature, v: RINKO output voltage (volt)

T: elapsed time of the sensor from the beginning of first station in calculation group in days

O2sat: dissolved oxygen saturation by Garcìa and Gordon (1992) (μmol/kg)[O2]: dissolved oxygen concentration (μmol/kg)
c1–c9: determined by minimizing differences between CTD oxygen and bottle dissolved oxygen byquasi-newton method (Shanno, 1970).
Table 4.2.7. Dissolved oxygen correction coefficient summary. (Bold: accepted sensor)
S/N

26

26

8

8

Stations

RF5802 – 5860

RF5861 – 5892

RF5802 – 5860

RF5861 – 5892

c1

1.73006

1.72453

1.67527

1.6871c2

2.51830 × 10–2

2.08129 × 10–2

2.37825 × 10–2

2.24579 × 10c3

1.27010 × 10–4

1.24172 × 10–4

1.39559 × 10

–4

1.46657 × 10

c4

–6.36633 × 10–4

–1.47249 × 10–3

–5.43750 × 10–4

–8.87988 × 10–4

c5

–1.37504 × 10–1

–1.25650 × 10–1

–1.26993 × 10–1

–1.23317 × 10–1

c6

3.10461 × 10–1

3.06680 × 10–1

3.03342 × 10–1

3.01840 × 10 –1

c7–3.17909 × 10–4

–3.78316 × 10–4

3.51648 × 10–4

–2.87248 × 10–4

c8

2.31975 × 10–4

4.41860 × 10–4

2.68911 × 10–4

4.32304 × 10–4

c9

8.01352 × 10–2

8.30326 × 10–2

8.52965 × 10–2

8.68856 × 10–2

–2

–4

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Table 4.2.8. Dissolved oxygen correction summary for S/N 026.
Pressure < 950 dbar
Stations

Num

Pressure ≥ 950 dbar

AverageStd(μmol/kg)(μmol/kg)

Num

AverageStd(μmol/kg)(μmol/kg)

RF5802 – 5860

1003

0.02

0.89

1010

0.00

0.26

RF5861 – 5892

608

0.00

1.1

508

0.00

0.25

Table 4.2.9. Dissolved oxygen correction summary for S/N 008.
Pressure < 950 dbar
Stations

Num

Pressure ≥ 950 dbar

AverageStd(μmol/kg)(μmol/kg)

Num

AverageStd(μmol/kg)(μmol/kg)

RF5802 – 5860

1003

–0.01

0.92

1010

0.00

0.28

RF5861 – 5892

608

–0.01

1.1

508

0.00

0.25

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Figure 4.2.6. Difference between the CTD oxygen (S/N 026) and bottle dissolved oxygen on Leg 1. Red
dots in upper two panels indicate the result of calibration. Lower two panels show histograms of thedifferences between calibrated oxygen and bottle oxygen.

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Figure 4.2.7. Difference between the CTD oxygen (S/N 026) and bottle dissolved oxygen on Leg 2. Red
dots in upper two panels indicate the results of calibration. Lower two panels show histograms of thedifferences between calibrated oxygen and bottle oxygen.

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4-2-4. Post-cruise calibration
After the cruise, post-cruise calibration of sensors was performed by the manufacturer, as shown
below. We confirmed that the calibration of these sensors did not change significantly during the cruise.

a. Temperature (ITS-90): SBE 3plus
Post-cruise sensor calibration of the SBE 3plus
S/N 4321(primary), 19 Sep. 2016g=

4.39116016 × 10–3

j=1.95929821 × 10–6

h=6.47366452 × 10–4

f0=

1000.000i=

2.30828080 × 10–5

S/N 4437(secondary), 19 Sep. 2016g=

4.33401810 × 10–3

j=1.79907757 × 10–6

h=6.37045349 × 10–4

f0=

1000.000i=

2.09767140 × 10–5

b. Deep Ocean Standards Thermometer Temperature (ITS-90): SBE 35
Post-cruise sensor calibration of the SBE 35
S/N 0062, 09 Feb. 2017 (2nd step: fixed point calibration)
Slope = 1.000008, Offset = –0.001087

c. Conductivity: SBE 4C
Post-cruise sensor calibration for the SBE 4C
S/N 2842(primary), 06 Oct. 2016g=

–1.01302170

j=4.07480188 × 10–5h=1.38907873

CPcor

=

–9.57 × 10–8i=

3.47775107 × 10–4

CTcor

=

3.25 × 10–6

S/N 4316(secondary), 06 Oct. 2016g=

–9.87043982

j=2.44022577 × 10–4

h=1.291116243

CPcor

=

–9.57 × 10–8

i=–2.61078862 × 10–3

CTcor

=

3.25 × 10–6

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5.

Best practices for quality control of bottle salinity, oxygen concentration, nutrient
concentrations, and carbonate system parameters

This section describes best practices for water sampling and quality control of measurements ofbottle salinity, oxygen concentrations, nutrient concentrations, carbonate system parameters, Chl. aconcentrations, and trace metal concentrations.
Original cruise report of MR15-05 is available at
http://www.godac.jamstec.go.jp/catalog/data/doc_catalog/media/MR15-05_leg1_all.pdf (accessedon 19 March 2020) and that of RF16-06 is available at https://cchdo.ucsd.edu/cruise/49UP20160703(accessed on 23 March 2020). In this section 5, we use many materials from the cruise reports andrevised them to fit for this guideline.

5-1. Quality control for bottle sampling parameters in the case of the MR15-05 cruise (JAMSTEC)
5-1-1. Bottle salinity
i. Standard Seawater

We set salinometer as appropriately based on an GO-SHIP manual of salinity measurements(Kawano 2010). In case of MR15-05 cruiess, standardization control was set to 715 and the value of
STANDBY was 5216 ± 0001 and that of ZERO was 0.00000 or ±0.00001. We used IAPSO Standard
Seawater batch P157, whose conductivity ratio is 0.99985 (the double conductivity ratio is 1.99970) as
the standard for salinity measurement. We measured the salinity of 66 bottles of the Standard Seawater
during the cruise. Figure 3.2.1 shows the history of the double conductivity ratio measurements of theStandard Seawater.
Temporal drift of the salinometer was corrected by using the Standard Seawater measurements.
Linear temporal drift of the salinometer was estimated from the Standard Seawater measurements byusing the least squares method (thin black line in Figure 5.2.1). No remarkable temporal drift was
detected from the Standard Seawater measurements. The average of the double conductivity ratio was
1.99968; the standard deviation, 0.00001, was equivalent to a salinity of 0.0002.

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Figure 5.2.1. History of double conductivity ratio measurements of Standard Seawater (P157).
Horizontal and vertical axes indicate the date and double conductivity ratio, respectively. Red dots
indicate raw data, and blue dots indicate corrected data.
ii. Sub-Standard Seawater

We also used sub-standard seawater, which was deep-sea water filtered through a filter with a poresize of 0.45 µm and stored in a 20-liter cubitainer made of polyethylene and stirred for at least 24 hours
before measuring. The salinity was measured every 6–8 samples to check for possible sudden drift ofthe salinometer. Throughout the measurements, there was no detectable sudden drift of the salinometer.
We took 257 pairs of duplicate samples collected from the same Niskin bottle. Figure 5.2.2 shows ahistogram of the absolute difference between replicate samples. The root-mean-square error for 256
pairs of replicate samples, 0.0002, was acceptable from the standpoint of data quality.

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Figure 5.2.2. Histogram of the absolute differences between replicate samples. Horizontal axis isabsolute difference of salinity, and vertical axis is frequency.
iv. Duplicate Samples
In this cruise, we took 36 samples at station 900 collected from different Niskin bottles at the samepressure (2000 dbar) instead of taking duplicate samples. The average salinity ± standard deviation was
34.7300 ± 0.0002.
5-1-2. Bottle oxygenStandardization
The concentration of sodium thiosulfate titrant (ca. 0.025 M) was determined with a potassium iodate
solution. Pure potassium iodate was dried in an oven at 130°C. Then 1.7835 g of potassium iodate thatwas weighed out accurately was dissolved in deionized water and diluted to a final volume of 5 liters ina calibrated volumetric flask (0.001667 M). Next, 10 cm3 of the standard potassium iodate solution wasadded to a flask using a volume-calibrated dispenser. Then, 90 cm3 of deionized water, 1 cm3 of sulfuric
acid solution, and 0.5 cm3 of pickling reagent solution II and I were added into the flask in that order.
The volume of the sodium thiosulfate titrant (usually the average of 5 measurements) equaled themolarity of the sodium thiosulfate titrant. Table 3.4.1 shows the result of the standardization during thiscruise. The coefficient of variation (C.V.) for the standardizations was 0.016 ± 0.005% (standard
deviation, n = 16), corresponds to c.a. 0.05 µmol kg−1 of dissolved oxygen concentration.
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Determination of the blank
The oxygen in the pickling reagents I (0.5 cm3) and II (0.5 cm3) was assumed to be 3.8 × 10−8 mol(Murray et al., 1968). The blank from the presence of redox species apart from oxygen in the reagents(pickling reagents I, II, and the sulfuric acid solution) was determined as follows. Aliquots of 1 and 2
cm3 of the potassium iodate solution were added to two separate flasks, respectively. Then 100 cm3 ofdeionized water, 1 cm3 of sulfuric acid solution, and 0.5 cm3 of pickling reagent solution II and I eachwere added to the two flasks, in that order. The blank was equated to the difference between twice thefirst (1 cm3 of KIO3) titrated volume of sodium thiosulfate and the second (2 cm3 of KIO3) titrated
volume. The results of triplicate blank determinations were averaged (Table 5.2.1). The average blankvalues for standard iodate solutions DOT-6 and DOT-8 were 0.002 ± 0.002 (standard deviation, n = 8)
and 0.000 ± 0.002 (standard deviation, n = 8) cm3, respectively.
Table 5.2.1 Results of the standardization (end point, E.P.) and the blank determinations (cm3) for
standard iodate solutions DOT-6 and DOT-8.
Date (UTC)KIO3 No.

DOT-6

Na2S2O3
No.

E.P.

DOT-8

Blank

E.P.

Blank

Stations

2015/12/27

K1504E02

T1505A

3.962

0.002

3.963

0.000

001-015

2015/12/30

K1504E03

T1505A

3.965

0.003

3.965

0.001

016-026

2016/1/3

K1504E04

T1505B

3.957

0.000

3.959

0.001

027-041

2016/1/6

K1504E05

T1505B

3.957

0.002

3.958

0.000

042-052

Replicate sample measurements
From the routine CTD casts at all the stations, duplicate samples were collected at pressures of 50,
400, 1800, and 3500 dbars. The total number of duplicate sample pairs that were satisfactory formeasurement purposes (flagged as 2) was 170 (Figure 5.2.3). The standard deviation of the replicate
measurements, calculated by procedure SOP23 in DOE (1994), was 0.06 µmol O2 kg−1.

Figure 5.2.3 Magnitude of difference of oxygen concentrations between duplicate samples versus
oxygen concentration.
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Duplicate sample measurements
At Station 900 (test), duplicate samples were taken at 2000 dbar from all the Niskin bottles (36bottles, Table 5.2.2) The standard deviation of the duplicate measurements was calculated to be 0.09
µmol kg−1, which was nearly equivalent to that of the replicate sample measurements (0.06 µmol kg−1).
Table 5.2.2 Results of duplicate sample measurements.
Duplicated Niskin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36

Niskin
X12J01
X12J02
X12J03
X12104
X12J05
X12J06
X12J07
X12J08
X12J09
X12J10
X12J11
X12J12
X12J13
X12J14
X12J15
X12J16
X12J17
X12J18
X12J19
X12J20
X12J21
X12J22
X12J23
X12J24
X12J25
X12J26
X12J27
X12J28
X12J29
X12J30
X12J31
X12J32
X12J33
X12J34
X12J35
X12J36

Pressure (db)
2000
2000
2001
2001
2000
2000
2000
2000
2000
2000
2001
2001
2001
2001
2001
2001
2000
1999
2000
1999
2000
2001
2001
2001
2000
2001
2000
2001
2001
2001
2001
2001
2001
2001
2000
2000

-1

Oxygen (µmol kg )139.67139.74139.73139.91139.78139.91139.85139.93139.87139.85139.96139.87140.02139.86139.89139.92139.97139.86139.97139.99139.94139.90139.97139.98139.91139.94139.93139.70139.89139.78139.88139.79140.02139.92139.77139.85

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CSK standard measurements
The CSK standard is a commercial potassium iodate solution (0.0100 N) for analysis of dissolved
oxygen. We titrated the CSK standard solution (Lot KPG6393) against our KIO3 standard solution (Lot
K1504E01) before the cruise on 25 Dec. 2016. The normalities of our KIO3 standard solutions were
calculated to be 0.010006 ± 0.000002 N and 0.010006 ± 0.000002 N for DOT-6 and DOT-8,
respectively.
Quality control flag assignment
Quality flag values were assigned to oxygen measurements using the code defined in Table 0.2 of
the WOCE Hydrographic Program Office Report WHPO 91-1 Rev.2 section 4.5.2 (Joyce et al., 1994).
Measurement flags of 2 (good), 3 (questionable), 4 (bad), and 5 (missing) were assigned (Table 3.4.3).
To distinguish between flags of 2, 3, and 4, we followed the flagging procedure as below:
a. Bottle oxygen concentration at the sampling layer was plotted against sampling pressure.
Any points not lying on a generally smooth trend were noted.
b. The difference between bottle oxygen and CTD oxygen was then plotted against
sampling pressure. If a datum deviated from a group of plots, it was flagged 3.
c. Vertical sections against pressure and potential density were drawn. If a datum wasanomalous on the section plots, the datum flag was degraded from 2 to 3, or from 3 to 4.
d. If there was a problem in the measurement, the datum was flagged 4.
e. If the bottle flag was 4 (did not trip correctly), the datum was flagged 4 (bad). In case thebottle flag was 3 (leaking) or 5 (unknown problem), the datum was flagged based on
steps a, b, c, and d.
Table 5.2.3 Summary of number of assigned quality control flags.
FlagDefinition

Number*

2

Good

1363

3

Questionable

0

4

Bad

0

5

Not report (missing)

0

Total

1363

*Replicate samples (n = 170) were not included.
In this chapter 4, we will discuss about quality control flag assignment more general insection 5-4.

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5-1-3. Nutrient measurements and estimated uncertainty using CRM
To obtain accurate and high-quality nutrient concentrations, large numbers of bottles of nutrients inseawater CRM have been prepared and used during previous cruises. In the previous worldwide
expeditions, such as WOCE cruises, high reproducibility and precision of nutrient measurements wererequired (Joyce and Corry, 1994). Because no standards were available for the measurement of nutrientsin seawater at that time, the requirements were described in terms of precision. The required precision
was 1%, 1–2%, 1–3% for nitrate, phosphate and silicate, respectively. Although nutrient data from the
WOCE one-time survey was of unprecedented quality and coverage because of the great care taken insampling and measurements, differences of nutrient concentrations at crossover points were still foundamong the expeditions (Aoyama and Joyce, 1996, Mordy et al., 2000, Gouretski and Jancke, 2001,
Aoyama, 2019). For instance, the mean offset of nitrate concentrations in deep waters was 0.5 µmol
kg−1 for 345 crossovers in the world oceans, though the maximum was 1.7 µmol kg−1 (Gouretski andJancke, 2001). At the 31 crossover points in the Pacific WHP one-time lines, the WOCE standard of
reproducibility for nitrate of 1% was fulfilled at about half of the crossover points, and the maximum
difference was 7% at deeper layers below 1.6°C in potential temperature (Aoyama and Joyce, 1996). In
the MR1505 cruises, we used 6 lots of CRM (lots BY, BU, CA, BW, BV, and BZ) to ensurecomparability and traceability to SI. Because we did duplicate measurements for all samples, we could
look at uncertainty based on differences between results of duplicate samples.
Precision of nitrate analyses during this cruise
The precision of nitrate analyses during this cruise was evaluated based on 7–11 measurements ofhighest concentration solution of inhouse standard, eg. C-6, that were made every 8 to 13 samples. The
precision for nitrate was better than 0.2% (Figure 5.2.4) and was generally good considering that themedian analytical precisions during the R/V Mirai cruises conducted in 2009–2014 was 0.11% for nitrate.

Figure 5.2.4 Time series of precision of nitrate during MR1505. Red circles indicate unit 1of analyzer,
and blue diamonds indicate unit 2 of analyzer.
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Control chart: CRM lot BV measurement during this cruise
CRM lot BV was measured every run to monitor the comparability among runs. The results of lot
BV during this cruise are shown as Figure 5.2.5. Error bars represent analytical precision in Figure 5.2.4.
As shown in Fig. 5.2.5, the measured concentrations of CRM lot BV were well within the uncertaintyof the certified value of lot BV.

Figure 5.2.5 Control chart of CRM lot BV nitrate concentrations measured during the MR1505 cruise.
CarryoverWe can also summarize the magnitudes of carryover throughout the cruise. These were within
acceptable limits, as shown in Figure 5.2.6. The carryover of the nitrate measurement had a bias thatwas equipment-specific. The mean carryover was 0.06% at Unit 2 of analyzer and 0.17% at Unit 1 ofanalyzer. We carried out the maintenance for Unit 1 by replacing the glass coils with new glass coils andinstalling a new transmission tube before station 22. This maintenance solved the bias problem.

Figure 5.2.6 Time series of carryover of nitrate during MR1505. Red circles indicate unit 1, and blue
diamonds indicate unit 2.
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Improvement of reduction rate during nitrate measurements
When we reduced the sample flow rate, we achieved a stable and high rate of nitrate reduction tonitrite. The mean rate for 50 runs was 99.7% (± 0.4–0.7%) during this cruise, as shown in Figure 5.2.7.

Figure 5.2.7 Time series of reduction of nitrate during MR1505
Estimation of uncertainty of nitrate concentrations
An empirical equation, to estimate the uncertainty of the measurement of nitrate was based on
measurements of 24 sets of CRMs during this cruise, as shown in Figure 5.2.8.

Figure 5.2.8 Estimation of uncertainty for nitrate during MR1505.

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An empirical equation to estimate the uncertainty of nitrate measurements was based on
measurements of 24 sets of CRMs during this cruise.
Nitrate Concentration (Cno3) in μmol kg−1:
Uncertainty of measurement of nitrate (%) =0.08 + 1.49 * (1 / Cno3) + 0.02 * (1 / Cno3) *(1 / Cno3)
where Cno3 is the nitrate concentration of the sample.
5-1-4. Chlorophyll a
Because there is no established quality control method for Chl. a, a quality check can be done asfollows.
Are there any mistakes in the filtration and measurement methods of the collected water sample?
Are the results of replicate samples too far apart?
Is it far from the shape of the vertical profile of the CTD fluorescence sensor?
(K. Sasaok, personal communication)

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5-2. Quality control for bottle sampling parameters in the case of the RF16-06 cruise (JMA)
5-2-1. Bottle salinity

a. Instrument
Salinometer: AUTOSAL 8400B (S/N72103; Guildline Instruments Ltd., Canada)
Thermometer: Guildline platinum thermometers model 9450 (to monitor ambient temperature and bathtemperature)b. Sampling and measurement
The measurement system was almost the same as the system described by Kawano (2010).
Algorithm for the Practical Salinity Scale, 1978 (PSS-78; UNESCO, 1981) was employed to convert the
conductivity ratios to salinities.

c. Ambient temperature, bath temperature, and surface seawater measurements

Figure 5.2.1. The upper panel, red line, black line, and blue line indicate time-series of ambient
temperature, average ambient temperature, and bath temperature during the cruise. The lower panel,
black dots, and red dots indicate raw and corrected time-series of the duplicate conductivity ratios of thestandard seawater (IAPSO Standard Sea Water: P159 (K15=0.99998)).

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d.

Replicate and duplicate samples

We took replicate (pair of water samples taken from a single Niskin bottle) and duplicate (pair ofwater samples taken from different Niskin bottles closed at the same depth) samples for bottle salinity
throughout the cruise. Table 5.2.1 summarizes the results of the analyses. Figure 5.2.2 shows detailsof the results. The calculation of the standard deviation from the difference of sets was based on aprocedure (SOP 23) in DOE (1994).
Table 5.2.1. Summary of replicate and duplicate salinity analyses.
Measurement
Replicate

Average difference ± S.D.
0.0003 ± 0.0003 (N = 327)

Duplicate0.0007 ± 0.0008 (N = 137)

Figure 5.2.2. Results of (left) replicate and (right) duplicate analyses during the cruise against (a) station
number, (b) pressure (c) salinity, and (d) histogram of the measurements. Green line indicates the meanof the differences of salinity of replicate/duplicate analyses.

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e. Summary of assigned quality control flags
Table 5.2.2. Summary of assigned quality control flags
Flag
Definition
Number of samples
2

Good

2578

3

Questionable04

Bad (Faulty)

238

5

Not reported

06

Replicate measurements

334

Total number of samples

3150

5-2-2. Bottle Oxygena. Instrument
Detector: DOT-01X (Kimoto Electronic, Japan)
Burette: APB-510 (Kyoto Electronic, Japan)

b. Sampling and measurement
Methods of seawater sampling, measurement, and calculation of dissolved oxygen concentration
were based on an IOCCP Report (Langdon, 2010). Standard KIO3 solutions were prepared
gravimetrically using the highest purity standard substance KIO3 (Lot. No. TLG0272, Wako Pure
Chemical, Japan). Table 5.2.3 shows the batch list of prepared standard KIO3 solutions.
Table 5.2.3. Batch list of the standard KIO3 solutions.
KIO3 batch
20160330-3
20160329-2

Concentration and uncertainty (k = 2) at
20°C. Unit is mol L−1.
0.0016670 ± 0.0000007
0.0016667 ± 0.0000007

Purpose of use
Standardization (main use)
Mutual comparisonc. Standardization
The concentration of the Na2S2O3 titrant was determined with the standard KIO3 solution“20160330-3”, based on the methods of an IOCCP Report (Langdon, 2010). Figure 5.2.3 shows theresults of standardization during the cruise. The standard deviation of the concentration at 20°C wasdetermined through standardization and was used in the calculation of uncertainty.

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Figure 5.2.3. Calculated concentration of Na2S2O3 solution at 20°C in standardization during Leg 1 (top)and Leg 2 (bottom). Different colours of plots indicate different batches of Na2S2O3 solution; red (blueand light blue) plots correspond to the left (right) y-axis. Error bars of plots show standard deviations ofconcentration of Na2S2O3 in the measurements. Thick and dashed lines denote the mean and twice thestandard deviations for the batch measurements, respectively.

d. Blank
The blank in an oxygen measurement (reagent blank ; Vblk) is equal to the sum of two terms as follows:
Vblk = Vblk, ep + Vblk, reg
where Vblk, ep represents a blank due to differences between the measured end-point and the equivalence
point, and Vblk, reg is a blank associated with oxidants or reductants in the reagent. The reagent blank Vblk
was determined by the methods described in the IOCCP Report (Langdon, 2010). Because we used two
sets (set A and B) of pickling reagent I and II, the blanks in each set were determined separately (Figure
5.2.4).

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Figure 5.2.4. Reagent blank (Vblk, dw) determination for set A (top) and set B (bottom). Error bars ofplots show standard deviations of the measurements. Thick and dashed lines denote the mean and themean ± twice the standard deviation for the batch measurement, respectively.

e. Replicate and duplicate analyses
We took replicate and duplicate samples of dissolved oxygen throughout the cruise. Table 5.2.4
summarizes the results of the analyses. Figure 5.2.5 shows details of the results. The calculation of thestandard deviation from the difference of sets was based on a procedure (SOP 23) in DOE (1994).

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Table 5.2.4. Summary of replicate and duplicate measurements.
Measurement
Replicate

Average magnitude ofdifference ± S.D. (μmol kg−1)
0.14 ± 0.13 (N = 348)

Duplicate0.26 ± 0.26 (N = 165)

Figure 5.2.5. Results of (left) replicate and (right) duplicate measurements during the cruise against(a) station number, (b) pressure, and (c) concentration of dissolved oxygen. Green lines denote theaverage of the measurements. Bottom panels (d) show histograms of the measurements.

f. Comparisons between standard KIO3 solutions
During the cruise, comparisons were made between different lots of standard KIO3 solutions toconfirm the accuracy of our oxygen measurements and the bias of a standard KIO3 solution. A
concentration of the standard KIO3 solution “20160329-2” was determined using Na2S2O3 solution
standardized with the KIO3 solution “20160330-3”, and the difference between the measured value andthe theoretical one. Good agreement between two standards confirmed that there was no systematic shiftin oxygen measurements during the cruise (Figure 5.2.6).

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Figure 5.2.6. Result of comparison of standard KIO3 solutions during Leg 1 (top) and Leg 2 (bottom).
Circles and error bars show mean of the measured value and its uncertainty (k = 2), respectively.
Thick and dashed lines in blue denote the mean and the mean ± twice the standard deviations,
respectively, for the measurements throughout the leg. Green thin line and light green thick line
denote the nominal concentration and its uncertainty (k = 2) of standard KIO3 solution “201603292”.

g. Quality control flag assignment
A quality flag value was assigned to oxygen measurements, as shown in Table 5.2.5, using the code
defined in IOCCP Report No. 14 (Swift, 2010).

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Table 5.2.5. Summary of assigned quality control flags.
FlagDefinition

Number of samples

2

Good

3

Questionable104

Bad (Faulty)

19

5

Not reported

06

Replicate measurements

348

Total number of samples

3248

2871

h. Uncertainty
Oxygen measurement involves various uncertainties; determination of glass bottles volume,
repeatability and systematic error of burette discharge, repeatability of pickling reagent discharges,
determination of reagent blank, standardization of Na2S2O3 solution, and uncertainty of KIO3
concentration. After taking into consideration the above uncertainties that could be evaluated, theexpanded uncertainty of bottle oxygen concentrations (T = 20, S = 34.5) was estimated, as shown in
Table 5.2.6. However, it is difficult to determine a strict uncertainty for oxygen concentration because
there is no reference material for oxygen measurement.
Table 5.2.6. Expanded uncertainty (k = 2) of bottle oxygen during the cruise.
O2 conc. (μmol kg−1)

Uncertainty (μmol kg−1)

20

0.33

30

0.34

50

0.35

70

0.36

100

0.39

150

0.45

200

0.53

250

0.61

300

0.70

400

0.89

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5-2-3. Nutrientsa.

Instrument

The nutrient analyses were carried out on a four-channel AutoAnalyzer III (BL TEC K.K., Japan)
for four nutrients: nitrate+nitrite, nitrite, phosphate, and silicate.
b. In-house standard solutions
The batches of the reagents used for in-house standards are listed in Table 5.2.7.
Table 5.2.7. List of reagents for the standards used in the cruise.
NitrateNitritePhosphate
Silicate

Name
Potassium nitrate 99.995 suprapur®

CAS No7757-79-1

Lot. noB0771365

Industries
Merck KGaA

Sodium nitrite GR for analysis
ACS, Reag. Ph Eur
Potassium dihydrogen phosphateanhydrous 99.995 suprapur®
Silicon standard solution 1000 mg/l
Si*7632-00-0

A0723349

Merck KGaA

7778-77-0

B1144508

Merck KGaA-

HC54715536

Merck KGaA

* Traceable to NIST-SRM3150
c. Certified reference material
Certified reference material for nutrients in seawater (hereafter CRM), which was prepared by theGeneral Environmental Technos company (KANSO Technos, Japan), was used for every analysis ateach hydrographic station. Use of CRMs for the analysis of seawater ensures stable comparability anduncertainty of data.
CRMs used in the cruise are shown in Table 5.2.8.
Table 5.2.8. Certified concentration and uncertainty (k = 2) of CRMs. Unit is μmol kg−1.
CRM-BY
CRM-BW
CRM-CB
CRM-BZ

Nitrate0.024 ± 0.019*
24.59 ± 0.20
35.79 ± 0.27
43.35 ± 0.33

Nitrite0.019 ± 0.0085*
0.067 ± 0.010
0.116 ± 0.0057
0.215 ± 0.011

Phosphate
0.039 ± 0.010*
1.541 ± 0.014
2.520 ± 0.022
3.056 ± 0.033

Silicate
1.763 ± 0.063
60.01 ± 0.42
109.2 ± 0.62
161.0 ± 0.93

* Reference value because concentration is under limit of quantitation
The CRM-BY and -CB were analyzed every analytical run using a newly opened CRM bottle ateach hydrographic station. The CRM-BW and -BZ were also analyzed every run but were newly opened
every 2 or 3 runs. Although this use of CRMs might be less common, we have confirmed the stabilityof the opened CRM bottles to be acceptable for oceanographic research. The CRM bottles were stored
in a laboratory in the ship, where the temperature was maintained at ~25°C.

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d. Replicate and duplicate analyses
We took replicate and duplicate samples of nutrients throughout the cruise. Table 5.2.9 summarizes
the results of the analyses. Figures 5.2.7–5.2.9 show details of the results. The calculation of the standard
deviation from the difference of sets of samples was based on a procedure (SOP 23) in DOE (1994).
Table 5.2.9. Average and standard deviation of difference of replicate and duplicate measurements
throughout the cruise. Unit is μmol kg−1.
Samples
Replicates
Duplicates

Nitrate+nitrite
0.021 ± 0.019 (N = 336)
0.041 ± 0.048 (N = 168)

Phosphate
0.002 ± 0.002 (N = 351)
0.004 ± 0.004 (N = 169)

Silicate
0.058 ± 0.058 (N = 351)
0.100 ± 0.099 (N = 170)

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Figure 5.2.7. Results of (left) replicate and (right) duplicate measurements of nitrate+nitrite throughout
the cruise versus (a) station number, (b) sampling pressure, (c) concentration, and (d) histogram of themeasurements. Green lines indicate the mean of the differences of concentrations based on
replicate/duplicate analyses.

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Figure 5.2.8. Same as Figure 5.2.7, but for phosphate.

Figure 5.2.9. Same as Figure 5.2.7, but for silicate.
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e. Measurement of CRMs
Table 5.2.10 summarizes the CRM measurements during the cruise. The CRM concentrations wereassigned with in-house standard solutions. Figures 5.2.10–5.2.13 show the measured concentrations of
CRM-BZ throughout the cruise.
Table 5.2.10. Summary of (upper) mean concentration and its standard deviation (unit: μmol kg−1),(middle) coefficient of variation (%), and (lower) total number of CRM measurements throughout thecruise.

CRM-BY
CRM-BW
CRM-CB
CRM-BZ

Nitrate+nitrite
0.094 ± 0.027
28.36%(N = 172)24.71 ± 0.06
0.27%
(N = 122)
35.97 ± 0.08
0.25%
(N = 172)43.66 ± 0.09
0.21%
(N = 122)

Nitrite0.023 ± 0.003
12.05%(N = 180)0.073 ± 0.002
2.34%(N = 128)
0.122 ± 0.002
1.64%(N = 180)
0.221 ± 0.003
1.22%(N = 128)

Phosphate
0.030 ± 0.011
37.86%(N = 180)
1.54 ± 0.01
0.72%
(N = 127)
2.52 ± 0.01
0.45%
(N = 180)
3.06 ± 0.01
0.39%
(N = 128)

Silicate
1.71 ± 0.06
3.63%
(N = 180)
59.93 ± 0.10
0.16%
(N = 128)109.39 ± 0.13
0.12%
(N = 180)161.04 ± 0.19
0.12%
(N = 128)

Figure 5.2.10. Time-series of measured concentration of nitrate+nitrite of CRM-BZ throughout thecruise. Closed and open circles indicate the newly and previously opened bottle, respectively. Thick anddashed lines denote the mean and the mean ± twice the standard deviations of the measurements
throughout the cruise, respectively.

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Figure 5.2.11. Same as Figure 5.2.10, but for nitrite.

Figure 5.2.12. Same as Figure 5.2.10, but for phosphate.

Figure 5.2.13. Same as Figure 5.2.10, but for silicate.
f. Precision of analysis in a run
To monitor the precision of the analyses, the same samples were repeatedly measured in a sample
array during a run. For this purpose, a C-5 standard solution was randomly inserted in every 2–10
samples as a “check standard” (the number of standards was about 8–9) in the run. The precision was
estimated in terms of the coefficient of variation of the measurements. Table 5.2.11 summarizes theresults. The time series are shown in Figures 5.2.14–5.2.17.

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Figure 5.2.14. Time-series of the coefficients of variation of “check standard” measurements ofnitrate+nitrite throughout the cruise. Thick and dashed lines denote the mean and the mean ± twice thestandard deviations of the measurements throughout the cruise, respectively.

Figure 5.2.15. Same as Figure 5.2.14, but for nitrite.

Figure 5.2.16. Same as Figure 5.2.14, but for phosphate.

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Figure 5.2.17. Same as Figure 5.2.14, but for silicate.
Table 5.2.11. Summary of precisions of nutrient assays during the cruise.
NitriteNitrate+nitrite
Phosphate
Median
0.08%
0.08%
0.13%
Mean
0.08%
0.08%
0.13%
Minimum
0.03%
0.03%
0.06%
Maximum
0.21%
0.17%
0.26%
91
Number87
91

Silicate
0.08%
0.08%
0.03%
0.17%
91

g. Carryover
Carryover coefficients were determined during each analytical run. The C-5 standard (high standard)
was followed by two C-1 standards (low standards). Figures 5.2.18–5.2.21 show the time series of thecarryover coefficients.

Figure 5.2.18. Time-series of carryover coefficients in measurement of nitrate+nitrite throughout thecruise.

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Figure 5.2.19. Same as Figure 5.2.18, but for nitrite.

Figure 5.2.20. Same as Figure 5.2.18, but for phosphate.

Figure 5.2.21. Same as Figure 5.2.18, but for silicate.
h. Quality control flag assignment
A quality flag value was assigned to nutriment measurements, as shown in Table 5.2.12, using thecode defined in IOCCP Report No.14 (Swift, 2010).

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Table 5.2.12. Summary of assigned quality control flags.
Flag
2
3
4
5
6

i.

Definition
Good
Questionable
Bad (Faulty)
Not reported
Replicate measurements
Total number of samples

Nitrate+nitrite
2751
148
13
0
336
3248

Nitrite
2884
0
12
0
352
3248

Phosphate
2868
9
20
0
351
3248

Silicate
2885
0
12
0
351
3248

Uncertainty

Uncertainty associated with concentration level: Uc
Generally, an uncertainty of nutrient measurement is expressed as a function of its concentrationlevel which reflects that some components of uncertainty are relatively large in low concentration.
Empirically, the uncertainty associated with concentrations level (Uc) can be expressed as follows;
𝑈𝑈𝑐𝑐 (%) = 𝑎𝑎 + 𝑏𝑏 ∙ (1/𝐶𝐶𝑥𝑥 ) + 𝑐𝑐 ∙ (1/𝐶𝐶𝑥𝑥 )2,

where Cx is the concentration of sample for parameter X.
Using the coefficients of variation of the CRM measurements throughout the cruise, uncertainty
associated with concentrations of nitrate+nitrite, phosphate, and silicate were determined as follows:
𝑈𝑈𝑐𝑐-𝑛𝑛𝑛𝑛3 (%) = 0.018 + 2.071 ∙ (1/𝐶𝐶𝑛𝑛𝑛𝑛3 ) − 0.022 ∙ (1/𝐶𝐶𝑛𝑛𝑛𝑛3 )2
𝑈𝑈𝑐𝑐-𝑝𝑝𝑝𝑝4 (%) = −0.054 + 0.361 ∙ (1/𝐶𝐶𝑝𝑝𝑝𝑝4 )𝑈𝑈𝑐𝑐-𝑠𝑠𝑠𝑠𝑠𝑠 (%) = 0.02 + 3.66 ∙ (1/𝐶𝐶𝑠𝑠𝑠𝑠𝑠𝑠 ) + 1.10 ∙ (1/𝐶𝐶𝑠𝑠𝑠𝑠𝑠𝑠 )2,

where Cno3, Cpo4, and Csil represent concentrations of nitrate+nitrite, phosphate, and silicate, respectively,in μmol kg−1. Figures 5.2.22–5.2.24 show the calculated uncertainty graphically.

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Figure 5.2.22. Uncertainty of nitrate+nitrite associated with concentrations.

Figure 5.2.23. Same as Figure 5.2.22, but for phosphate.

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Figure 5.2.24. Same as Figure 5.2.22, but for silicate.

Uncertainty of analysis between runs: Us
Uncertainty of analysis among runs (Us) was evaluated based on the coefficient of variation of
measured concentrations of CRM-BZ with the highest concentration among the CRM lots throughout
the cruise, as shown in subsection (5-2-3e). The reason for using the CRM lot BZ to state Us is to exclude
the effect of uncertainty associated with lower concentration described previously. As is clear from thedefinition of Uc, Us is equal to Uc at nutrients concentrations of lot BZ. It is important to note that Us
includes all of uncertainties during the measurements throughout stations, namely uncertainties ofconcentrations of in-house standard solutions prepared for each run, uncertainties of slopes andintercepts of the linear calibration curve or coefficients of quadric calibration curve, precision of
measurement in a run (Ua) and between-bottle homogeneity of the CRM.
Uncertainty of analysis in a run: Ua
Uncertainty of analysis in a run (Ua) was evaluated based on the coefficient of variation of repeatedmeasurements of the “check standard” solution, as shown in subsection (5-2-3f). The Ua reflects theconditions associated with chemistry of colorimetric measurement of nutrients, and stability ofelectronic and optical parts of the instrument throughout a run. Under a well-controlled condition of themeasurements, Ua might show Poisson distribution with a mean as shown in Figures 5.2.14-5.2.17 andTable 5.2.11 and treated as a precision of measurement. Ua is a part of Uc at the concentration as statedin a previous section for Uc.
However, Ua may show larger value which was not expected from Poisson distribution of Ua due tothe malfunction of the instruments, larger ambient temperature change, human errors in handlingsamples and chemistries and contaminations of samples in a run. In the cruise, we observed that Ua of
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our measurement was usually small and well-controlled in most runs as shown in Figures 5.2.14–5.2.17
and Table 5.2.11. However, in a few runs, Ua showed high values which were over the mean ± twice
the standard deviations of Ua, suggesting that the measurement system might have some problems.
Uncertainty of CRM concentration: Ur
In the certification of CRM, the uncertainty of CRM concentrations (Ur) was stated by the
manufacturer (Table 5.2.8) as expanded uncertainty at k=2. This expanded uncertainty reflects theuncertainty of the Japan Calibration Service System (JCSS) solutions, characterization in assignment,
between-bottle homogeneity, and long term stability. We have ensured comparability between cruises
by ensuring that at least two lots of CRMs overlap between cruises. In comparison of nutrient
concentrations between cruises using KANSO CRMs in an organization, it was not necessary to include
Ur in the conclusive uncertainty of concentration of measured samples because comparability ofmeasurements was ensured in an organization as stated previously.

Conclusive uncertainty of nutrient measurements of samples: U
To determine the conclusive uncertainty of nutrient measurements of samples (U), we use twofunctions depending on Ua value acquired at each run as follows:
When Ua was small and measurement was well-controlled condition, the conclusive uncertainty ofnutrient measurements of samples, U, might be as below.
𝑈𝑈 = 𝑈𝑈𝑐𝑐

When Ua was relative large and the measurement might have some problems, the conclusive
uncertainty of nutrient measurements of samples, U, can be expanded as below.
𝑈𝑈 = �𝑈𝑈𝑐𝑐2 + 𝑈𝑈𝑎𝑎2.

When Ua was relative large and the measurement might have some problems, the equation of U is
defined as to include Ua to evaluate U, although Ua partly overlaps with Uc. It means that the equation
overestimates the conclusive uncertainty of samples. On the other hand, for low concentration there is apossibility that the equation not only overestimates but also underestimates the conclusive uncertainty
because the functional shape of Uc in lower concentration might not be the same and cannot be verified.
However, we believe that the applying the above function might be better way to evaluate the conclusive
uncertainty of nutrient measurements of samples because we can do realistic evaluation of uncertainties
of nutrient concentrations of samples which were obtained under relatively unstable conditions, larger
Ua as well as the evaluation of them under normal and good conditions of measurements of nutrients.
5-2-4. Total Dissolved Inorganic Carbon (DIC)

a. Instrument
The measurements of DIC were carried out with a DIC/TA analyzer (Nihon ANS Co. Ltd, Japan).
We used two analyzers concurrently. These analyzers are designated as apparatus A and B.
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b. Sampling and measurement
Methods of seawater sampling, poisoning, measurement, and calculation of DIC concentrations
were based on the Standard Operating Procedure (SOP) described in PICES Special Publication 3, SOP2 (Dickson et al., 2007). DIC was determined by coulometric analysis (Johnson et al., 1985, 1987) using
an automated CO2 extraction unit and a coulometer.

c. Calibration
The concentration of DIC (CT) in moles per kilogram (mol kg−1) of seawater was calculated fromthe following equation:

𝐶𝐶T = 𝑁𝑁S / (𝑐𝑐𝑐𝑐  𝜌𝜌S )where NS is the counts of the coulometer (C), cV is the calibration factor (gC (mol L−1)−1), and ρS isthe density of seawater (kg L−1), which is calculated from the salinity of the sample and the watertemperature. The values of cV were determined by measurements of CRMs that were provided by Dr.
Andrew G. Dickson of the Scripps Institution of Oceanography. Table 5.2.14 provides information about
the CRM batches used in this cruise.
Table 5.2.14. Certified concentration and uncertainty (k = 2) of CRMs. Unit of DIC is μmol kg−1. Moreinformation is available at the NOAA web site(https://www.nodc.noaa.gov/ocads/oceans/Dickson_CRM/batches.html).
Batch number

150

DIC

2017.88 ± 0.36

Salinity

33.343

The CRM measurement was carried out at every station. After the cruise, a value of cV was assigned
to each apparatus (A, B). Table 5.2.15 summarizes the cV values. Figure 5.2.25 shows details.
Table 5.2.15. Assigned cV and its standard deviation for each apparatus during the cruise. Unit is gC(mol L−1)−1.
ApparatuscV
A

0.189806 ± 0.000232 (N = 85)

B0.190251 ± 0.000205 (N = 110)

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Figure 5.2.25. Results of the cV at each station assigned for apparatus (a) A and (b) B. The solid, dashed,
and dotted lines denote the mean, the mean ± twice the standard deviations, and the mean ± thrice thestandard deviations for all measurements, respectively.
The precision of the cV was equated to its coefficient of variation and was 0.122% for apparatus A and
0.108% for apparatus B. These precisions correspond to uncertainties of CT of 2.5 µmol kg−1 and 2.2µmol kg−1, respectively, in the standardization.
Finally, the value of CT was multiplied by 1.00067 (= 300.2/300.0) to correct for the effect of dilutionof the DIC concentration due to addition of 0.2 mL of mercury (II) chloride (HgCl2) solution in asampling bottle with a volume of ~300 mL.

d. Replicate and duplicate analyses
We took replicate and duplicate samples of DIC throughout the cruise. Table 5.2.16 summarizes
results of the measurements with each apparatus. Figures 5.2.26–5.2.27 show details of the results. The
calculation of the standard deviation from the difference of sets was based on a procedure (SOP 23) in
DOE (1994).

Table 5.2.16. Summary of replicate and duplicate measurements. Unit is µmol kg−1.
Apparatus A
Apparatus B
Measurement
Average magnitude of difference ± S.D.
Replicate
2.2 ± 2.0 (N = 51)
1.4 ± 1.3 (N = 67)
Duplicate

2.1 ± 1.9 (N = 30)

1.7 ± 1.5 (N = 42)

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Figure 5.2.26. Results of (left) replicate and (right) duplicate measurements during the cruise versus(a) station number, (b) pressure, and (c) CT determined by apparatus A. Green lines denote the averageof the measurements. Bottom panels (d) show histograms of the measurements.

Figure 5.2.27. Same as Figure 5.2.26, but for apparatus B.

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e. Measurements of CRMs and working reference materials
The precision of the measurements was monitored by using the CRMs and non-certified working
reference materials bottled at our laboratory. The CRM (batch 150) and working reference material
measurements were carried out at every station. In the measurements at a station, we measured theworking reference material first and the CRM second. If the results of these measurements wereconfirmed as good, measurements on seawater samples were begun. At the end of a sequence ofmeasurements at a station, another CRM bottle was measured. A CRM measurement was repeated twicefrom the same bottle. Table 5.2.17 summarizes the differences in the repeated measurements of theCRMs, the mean CT of the CRM measurements, and the mean CT of the working reference material
measurements. Figures 5.2.28–5.2.30 show the detailed results.
Table 5.2.17. Summary of difference and mean of CT in the repeated measurements of CRM and themean CT of the working reference material. These data are based on good measurements.
Unit is μmol kg−1 .
Working referencematerial

CRM
Mean
Ave. ± S.D.

Mean
Ave. ± S.D.

A

Average magnitudeof difference± S.D.
2.6 ± 2.4 (N = 44)

2017.9 ± 2.0 (N = 88)

2081.6 ± 3.3 (N = 22)B

1.7 ± 1.5 (N = 59)

2018.1 ± 2.2 (N = 118)

2082.0 ± 1.9 (N = 27)

Apparatus

Figure 5.2.28. The absolute difference (R) of CT in repeated measurements of CRM determined byapparatus A (left) and B (right). The solid line indicates the average of R (𝑅𝑅�). The dashed and dottedlines denote the upper warning limit (2.512𝑅𝑅� ) and upper control limit (3.267𝑅𝑅� ), respectively (seeDickson et al., 2007).

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Figure 5.2.29. The mean CT of measurements of CRM. The left (right) panel shows the results forapparatus A (B). The solid line indicates the mean of the measurements throughout the cruise. The
dashed and dotted lines denote upper/lower warning limits (mean ± 2S.D.) and upper/lower control limit(mean ± 3S.D.), respectively. The gray dashed line denotes certified concentration of the DIC of CRM.

Figure 5.2.30. Calculated CT of working reference material measured by apparatus (a) A and (b) B. The
solid, dashed, and dotted lines are the same as in Figure 5.2.29.

f. Comparison with other CRMs
At every few stations, other CRM batches (140, 145, 147, and 155) were measured to provide
comparisons with batch 150 to confirm the determination of CT in our measurements. For these CRM
measurements, CT was calculated from the cV determined from batch 150 measurement. Figure 5.2.31
shows the difference between the certified and calculated CT values.

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Figure 5.2.31. The differences between certified CT and calculated CT from batch 150 measurements.
Left and right panels show the results for apparatus A and B, respectively. Colors indicate CRM batches:
light blue: 140, blue: 145, green: 147, and red: 155.

g. Quality control flag assignment
A quality flag value was assigned to DIC measurements (Table 5.2.18) using the code defined in the
IOCCP Report No.14 (Swift, 2010).
Table 5.2.18. Summary of assigned quality control flags.
FlagDefinition

2

Good

3

Questionable3

4

Bad (Faulty)

85

Not reported

06

Replicate measurements
Total number of samples

Number of samples
1383

118
1512

5-2-5. Total Alkalinity (TA)a. Instrument
The measurement of TA was carried out with DIC/TA analysers (Nihon ANS Co. Ltd., Japan). The
methodology that these analysers use is based on an open titration cell. We concurrently used two
analysers, designated as apparatus A and B.

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b. Sampling and measurement
The procedure of seawater sampling of TA bottles and poisoning with mercury (II) chloride (HgCl2)
were based on the Standard Operating Procedure (SOP) described in PICES Special Publication 3(Dickson et al., 2007).
TA measurement is based on a one-step volumetric addition of hydrochloric acid (HCl) to a known
amount of sample seawater with prompt spectrophotometric measurement of excess acid using thesulfonephthalein indicator bromocresol green sodium salt (BCG) (Breland and Byrne, 1993). We useda mixed solution of HCl, BCG, and sodium chloride (NaCl) as reagent.

c. Standardization of HCl reagent
HCl reagents were prepared in our laboratory and divided into bottles (HCl batches). The
concentrations of HCl in the bottles were determined using measured CRMs provided by Dr. Andrew
G. Dickson of the Scripps Institution of Oceanography.
Table 5.2.19 provides information about the CRM batch used during this cruise.
Table 5.2.19. Certified concentration and uncertainty (k = 2) of CRM. Unit of TA is μmol kg–1.
More information is available at the NOAA web site(https://www.nodc.noaa.gov/ocads/oceans/Dickson_CRM/batches.html).
Batch number

150

TA

2214.71 ± 0.87

Salinity

33.343

The CRM measurement was carried out at every station. The apparent molarity of HClA of the titrant
was determined from the certified concentration of CRM.
The value of HClA was assigned for each HCl batch for each apparatus, as summarized in Table 5.2.20
and detailed in Figure 5.2.32.

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Table 5.2.20. Summary of assigned HClA for each HCl batch. The values reported are means andstandard deviations. Unit is mmol L−1.
Apparatus
A

B

Days
2–9
9–15
15–21
21–36
2–9
9–16
16–20
20–36
36–42

HCl Batch
A_1
A_2
A_3
A_4
B_1
B_2
B_3
B_4
B_5

HClA
49.9489 ± 0.0395 (N = 33)
49.9847 ± 0.0303 (N = 34)
49.9924 ± 0.0342 (N = 33)
50.0075 ± 0.0213 (N = 32)
50.0684 ± 0.0401 (N = 35)
50.0617 ± 0.0400 (N = 35)
50.0652 ± 0.0235 (N = 17)
50.0491 ± 0.0313 (N = 33)
50.0937 ± 0.0390 (N = 33)

Figure 5.2.32. Results of HClA measured by (a) apparatus A and (b) B. The HCl batch name is indicatedat the top of each graph, and vertical lines denote the day when the HCl batch was switched. The redsolid, dashed, and dotted lines denote the mean and the mean ± twice the standard deviations and thrice
the standard deviations for each HCl batch, respectively.
The precisions of HClA, defined as the coefficient of variation, were 0.0427–0.0791% for apparatus A
and 0.0470–0.0802% for apparatus B. They correspond to uncertainties of AT of 0.99–1.84 µmol kg−1
and 1.09–1.87 µmol kg−1, respectively, in the standardization.

d. Replicate and duplicate analyses
We took replicate and duplicate samples of TA throughout the cruise. Table 5.2.21 summarizes
results of the measurements by each apparatus. Figures 5.2.33–5.2.34 show detailed results. The
calculation of the standard deviation from the difference of sets was based on a procedure (SOP 23) in
DOE (1994).

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Table 5.2.21. Summary of replicate and duplicate measurements. Unit is μmol kg−1.

Measurement
Replicate
Duplicate

Apparatus A
Apparatus B
Average magnitude of difference ± S.D.
0.7 ± 0.6 (N = 54)
1.0 ± 0.9 (N = 68)
0.9 ± 0.9 (N = 29)

1.1 ± 1.1 (N = 42)

Figure 5.2.33. Results of (left) replicate and (right) duplicate measurements during the cruise against (a)station number, (b) pressure, and (c) equivalents of TA determined by apparatus A. Green lines denotethe averages of the measurements. Bottom panels (d) show histograms of the measurements.

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Figure 5.2.34. Same as Figure 5.2.33, but by apparatus B.

e. Measurement of CRMs and working reference materials
The precision of measurements was monitored by using the CRMs and non-certified working
reference materials bottled in our laboratory. The measurements of the CRMs and working referencematerials were the same as those used to measure DIC, except that the CRM measurement was repeated
3 times from the same bottle. Table 5.2.22 summarizes the differences in the repeated measurements of
CRM, the mean AT of the CRM measurements, and the mean AT of working reference material
measurements. Figures 5.2.35–5.2.37 show details.

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Table 5.2.22. Summary of difference and mean of AT in the repeated measurements of CRM, and meanof AT of the working reference material. These data are based on good measurements. Unit is μeq kg−1.
CRM

Working referencematerial

Days

HCl
Batches

Average magnitudeof difference ± S.D.

Mean
Ave. ± S.D.

Mean
Ave. ± S.D.

2–9

A_1

1.5 ± 1.2 (N = 10)2214.7 ± 1.6 (N = 39)2282.8 ± 1.6 (N = 5)

9–15

A_2

0.9 ± 0.8 (N = 10)2214.7 ± 1.2 (N = 36)2285.3 ± 1.3 (N = 6)

15–21

A_3

2.0 ± 1.6 (N = 11)2214.7 ± 0.7 (N = 33)2284.6 ± 0.5 (N = 3)

21–36

A_4

0.9 ± 0.7 (N = 10)2214.7 ± 0.8 (N = 33)

2285.1 ± 1.0 (N = 5)

2–9

B_1

1.4 ± 1.1 (N = 11)2214.7 ± 1.6 (N = 36)2282.4 ± 3.0 (N = 5)

9–16

B_2

0.8 ± 0.7 (N = 11)2214.7 ± 1.8 (N = 36)2285.9 ± 2.8 (N = 6)

16–20

B_3

0.8 ± 0.7 (N = 6)2214.7 ± 0.9 (N = 18)2285.5 ± 0.4 (N = 3)

20–36

B_4

1.3 ± 1.0 (N = 11)2214.3 ± 1.8 (N = 36)2284.4 ± 1.4 (N = 7)

36–42

B_5

1.4 ± 1.1 (N = 11)2214.7 ± 1.6 (N = 33)

2285.0 ± 1.7 (N = 5)

Figure 5.2.35. The absolute difference (R) of AT in repeated measurements of CRM determined byapparatus A (left) and B (right). The solid line indicates the average of R (𝑅𝑅�). The dashed and dottedlines denote the upper warning limit (2.512𝑅𝑅� ) and upper control limit (3.267𝑅𝑅� ), respectively (seeDickson et al., 2007).

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Figure 5.2.36. The mean AT of measurements of CRM. Left (right) panel shows the results for apparatus
A (B). The solid line indicates the mean of the measurements. The dashed and dotted lines denote theupper/lower warning limit (mean ± 2S.D.) and upper/lower control limit (mean ± 3S.D.), respectively.
The labels at the top of the graph and vertical lines have the same meaning as in Figure 5.2.32.

Figure 5.2.37. Calculated AT of working reference material measured by (a) apparatus A and (b) B. The
solid, dashed, and dotted lines have the same meaning as in Figure 5.2.36. The labels at the top of thegraph and vertical lines have the same meaning as in Figure 5.2.32.

f. Comparisons with other CRMs
Every few stations, other CRM batches (140, 145, 147, and 155) were measured to provide
comparisons with batch 150 and to confirm the determination of AT in our measurements. For these
CRM measurements, AT was calculated from HClA determined by batch 150 measurement. Figure 5.2.38
shows the differences between the certified and calculated AT.

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Figure 5.2.38. The differences between the certified AT and calculated AT from batch 150 measurements.
The panels show the results for (a) apparatus A and (b) B. The labels at the top of the graph and verticallines have the same meaning as in Figure 5.2.32. Colors indicate CRM batches; light blue: 140, blue:
145, green: 147, and red: 155.

g. Quality control flag assignment
A quality flag value was assigned to the TA measurements (Table 5.2.23) using the code defined in
IOCCP Report No.14 (Swift, 2010).
Table 5.2.23. Summary of assigned quality control flags.
FlagDefinition

2

Good

3

Questionable194

Bad (Faulty)

95

Not reported

06

Replicate measurements
Total number of samples

Number of samples
1362

122
1512

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5-2-6. pH

a. Instrument
The measurement of pH was carried out with a pH analyzer (Nihon ANS Co. Ltd, Japan).

b. Sampling and measurement
Methods of seawater sampling, spectrophotometric measurements using the indicator dye m-cresol
purple (hereafter mCP), and calculation of pHT (on the total hydrogen ion scale) were based on Saito etal. (2008). Finally, pHT was reported as the value at a temperature of 25°C.

c. Replicate and duplicate analyses
We took replicate and duplicate samples for pH determination throughout the cruise. Table 5.2.24
summarizes the results of the measurements. Figure 5.2.39 shows details of the results. The calculationof the standard deviation from the difference of sets of measurements was based on a procedure (SOP
23) in DOE (1994).

Table 5.2.24. Summary of replicate and duplicate measurements of pH.
Measurement
Replicate

Average magnitude ofdifference ± S.D.
0.0016 ± 0.0015 (N = 125)

Duplicate0.0017 ± 0.0015 (N = 73)

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Figure 5.2.39. Results of (left) replicate and (right) duplicate measurements during the cruise versus (a)station number, (b) pressure, and (c) pH. Green lines denote the averages of the measurements. Bottom
panels (d) show histograms of the measurements.

d. pH measurements of CRM and working reference materials
The precision of the measurements was monitored by using the CRMs and a non-certified working
reference material bottled in our laboratory. Although the pH value of the CRM was not defined, it could
be calculated from certified parameters(https://www.nodc.noaa.gov/ocads/oceans/Dickson_CRM/batches.html) based on the chemical
equilibrium of the DIC system. The pH of the CRM (batch 150) so calculated was estimated to be 7.8807.
Working reference material measurements were carried out first at every station. If the results of themeasurements were estimated to be good, sampling was begun. CRM (batch 150) measurements weredone at every few stations. One measurement was made from a bottle for sample analysis and two
measurements were made from a bottle for CRM.
The pHT of a CRM and a working reference material was immediately calculated with provisionalcoefficients estimated from the first station to the given station. Table 5.2.25 summarizes the difference
and mean of the pHT values between two measurements from a CRM bottle and the pHT value from aworking reference material. Figures 5.2.40–5.2.42 show detailed results.

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Table 5.2.25. Summary of difference and means of the pHT values for two measurements from a CRM
bottle, and mean of pHT from a working reference material, which was calculated with data with the
exception of questionable or bad data.
CRM

2–9

mCP
Batches1

Magnitude of difference
Ave. ± S.D.
0.0016 ± 0.0013 (N = 8)

Mean
Ave. ± S.D.
7.8768 ± 0.0020 (N = 8)

Working referencematerial
Mean
Ave. ± S.D.
7.8607 ± 0.0026 (N = 17)

9–21

2

0.0010 ± 0.0009 (N = 7)7.8769 ± 0.0024 (N = 7)7.8614 ± 0.0020 (N = 20)

21–40

3

0.0013 ± 0.0011 (N = 6)

7.8751 ± 0.0024 (N = 6)

7.8606 ± 0.0018 (N = 21)

Days

Figure 5.2.40. Difference of pHT between two measurements of a CRM bottle. The mCP batch name isshown above the graph, and vertical lines denote the day mCP batches were changed. The solid, dashed,
and dotted lines denote the average range (𝑅𝑅�), upper warning limit (2.512𝑅𝑅�), and upper control limit(3.267𝑅𝑅�) for each mCP batch bottle, respectively (see Dickson et al., 2007).

Figure 5.2.41. Mean of pHT values between two measurements of a CRM bottle. The mCP batch nameis shown above the graph, and vertical lines denote the day when the mCP batch was changed. The solid,
dashed, and dotted lines denote the mean, upper/lower warning limit (mean ± 2S.D.), and upper/lower
control limit (mean ± 3S.D.) for each mCP batch bottle, respectively (see Dickson et al., 2007).
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Figure 5.2.42. Same as Figure 5.2.41, but for the mean pHT of the working reference material.

e. Quality control flag assignment
A quality flag value was assigned to pH measurements (Table 5.2.26) using the code defined in IOCCP
Report No.14 (Swift, 2010).
Table 5.2.26. Summary of assigned quality control flags.
FlagDefinition
Number of samples
2

Good

3

Questionable3

4

Bad (Faulty)

85

Not reported

06

Replicate measurements
Total number of samples

1381

120
1512

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5-3. Quality control for trace metals in seawater during the R.V. Hakuho Maru KH-09-5 cruise(AORI, University of Tokyo)
GEOTRACES is an international research project with the goal of improving understanding of
biogeochemical cycles in the ocean. The Japan GEOTRACES group carried out a GEOTRACES
section cruise in the Indian Ocean during cruise KH-09-5 of the R.V. Hakuho Maru (Principle
Investigator: Dr. Toshitaka Gamo). The group also performed quality control of the trace metal data inaccord with the GEOTRACES guide, whose latest version is indicated in Figure 5.3.1.

Figure 5.3.1. Flow chart of data submission for GEOTRACES, cited from the webpage(https://www.geotraces.org/how-to-ensure-that-your-data-are-in-idp-flow-chart/).
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Before the cruise, the scientists were required to submit a pre-cruise metadata sheet(https://www.bodc.ac.uk/geotraces/cruises/documentation/).
After the cruise, the scientists were submitted a cruise report (Gomo, 2010).
5-3-1. MetadataSampling
The sampling procedure has been briefly described in Guideline of Ocean Observations Volume 2,
Chapter 1. Detailed sampling methods are also described in the GEOTRACES “cookbook”,
published on the web site (http://www.geotraces.org/images/Cookbook.pdf).

Analysis
The analytical methods have been described in the post-cruise metadata (Appendix II-3) for the KH09-5 cruise. The detection limit and the blank measurement values should be included in theanalytical methods. Analytical results of reference seawater samples (Guideline of Ocean
Observations Volume 3, Chapter 3) should also be reported in the post-cruise metadata.

5-3-2. Intercalibration
The trace metal data are expected to be published in “Intermediate Data Product of GEOTRACES(IDP)”. The data must be intercalibrated. The details of the intercalibration are described in Figure 5.3.2.

Figure 5. 3. 2. Schematic concept of intercalibration process for GEOTRACES data. This figure wasprepared for data submission to IDP2017(cited from the website,
http://www.geotraces.org/images/stories/documents/intercalibration/2017_SI_Flowchart.jpg).
First, we have to submit the post-cruise metadata, including sampling and analytical methods.
During the GEOTRACES section cruise, it was recommended that at least one crossover station be
occupied. If the data from other laboratories at the crossover station are available, we can compare andevaluate our data at the crossover station. Because there was no crossover station during the KH-09-5
cruise, we collected seawater samples at six depths in replicate at one station and distributed the samples
from these intercalibration depths to another laboratory in Taiwan for trace metal determinations.
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Because we submitted the post-cruise metadata and intercomparison data, our data during the KH-09-5
cruise were included in the GEOTRACES 2014 Intermediate Data Product (The GEOTRACES Group,2015).

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5-4. General procedure of quality control flag assignment
To distinguish between flags of 2, 3, and 4 for water sample measurements, we need followed theflagging procedure in general as below:
a. Concentration of bottle sample water at the sampling layer was plotted against samplingpressure. Any points not lying on a generally smooth trend were noted.
b. Vertical sections against pressure and potential density were drawn. If a datum wasanomalous on the section plots, the datum flag was degraded from 2 to 3, or from 3 to 4.
c. If there was a problem in the measurement, the datum was flagged 4.
d. If the bottle flag was 4 (did not trip correctly), the datum was flagged 4 (bad). In case thebottle flag was 3 (leaking) or 5 (unknown problem), the datum was flagged based on
steps a, b and c.
It is also very important, when assessing data, to look through the whole suite of data collectedconcurrently with "suspect" data. An error in drawing an sample, or an error in a single chemical analysis,
will have a much different signature in the overall data set than would an error due to a leaky or
mistripped bottle, or a genuine seawater anomaly. One of the most important considerations in assessing
a water sample is determining the actual level (from what actual pressure) the water in the Niskin bottle
represents. Consider that did the bottle close early or late and the bottle showed leak. Yet leaking,improperly closed, and late/early closed bottles are one of the leading causes of errors in water sample
data, and not always easy to find.
There is no single QC method for trace metals, such as for hydrographic data. We initially checked
whether the results of replicate samples were reasonable compared with the analytical precision. It has
also been recommended that subsamples be measured every 10 samples to check for possible drift of
the instrumental sensitivity and sudden contamination. If any data were questionable, we re-analyzed
the samples.
Great care must be taken to avoid contamination, especially during sampling, filtration, andmeasurement. During sampling and filtration, it is important to check the concentrations ofcontamination-prone trace metals like Fe and Zn in the same water sample. During the KH-09-5 cruise,
we did not detect any obvious contamination during sampling and filtration.

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6.

Quality control by 2D/3D property-property plots by Ocean Data View

6-1. Recommended softwares
Quality control with a control chart and duplicate measurements can provide an immediate alert ofa problem just after a measurement. To visualize property-property characteristics, we need appropriate
applications that enable visualization of 2D and/or 3D property-property plots.
At this moment the authors recommend use of Ocean Data View (ODV), which is a free software
package for the interactive exploration, analysis, and visualization of oceanographic and other georeferenced profile, time-series, trajectory, or sequence data. ODV runs on Windows, Mac OS X, Linux,
and UNIX (Solaris, Irix, AIX) systems. ODV data and configuration files are platform-independent andcan be exchanged between different systems (https://odv.awi.de/, accessed 19 October 2019). ODVprovides property/property plots of selected stations, scatter plots for sets of stations, color sections
along arbitrary cruise tracks, colour distributions on general iso-surfaces, temporal evolution plots oftracer fields, differences of tracer fields between repeats, geostrophic velocity sections, animations, andinterrupted maps.
Some oceanographers use Java OceanAtlas (http://joa.ucsd.edu, accessed on 19 March 2020), which
predates ODV and has many similar capabilities. Java Ocean Atlas (JOA) is a multi-OS application forviewing and exploring ocean vertical profile data. Along with a broad collection of data, JOA is theculmination of a long dream: a collection of some of the most useful oceanographic section data fromthe World Ocean with a multi-platform computer application for exploring those data.
Also, other applications such as Matlab are in wide use ( https://sea-mat.github.io/sea-mat/ accessedon 19 March 2020) . Time Series Tools, Mapping Tools, Hydrographic Tools, Data Interface Tools,
Atmosphere and Other Tools are available.
6-2. 2D/3D property/property plot by ODVIn this section, we show comparison among historical data achieved in World Ocean Database,
WOD and P6 cruises in 2003 and 2009. Property/property scatter plots generated with ODV for sets ofstations in the South Pacific Ocean over a region from 32–35°S and 170–178°W in the South Pacific
Ocean during the period from 1928 to 2017 are presented in this section. The data were downloaded
from the WOD select web page at https://www.nodc.noaa.gov/OC5/SELECT/dbsearch/dbsearch.html.
The format of the downloaded data is compatible with ODV software, so it is very easy to handle
the dataset.
We also show two examples from a part of the P06 line that was observed in 2003 and 2017.
We have prepared view files to present a map of stations, two vertical profiles of temperature andsalinity, 3D property/property plots for salinity vs. temperature with phosphate as colour shading andphosphate vs. nitrate with oxygen as colour shading for long-term history. A plot of total carbon vs.
nitrate with nitrate as colour shading has also been added for the 2003 cruise and 2017 cruise.
We can easily look at relationships among parameters using ODV software, as shown in Figures 6.1,
6.2, and 6.3. In general, if we look at a small region, we can assume that properties in the region arehomogenous. For example, a phosphate vs. nitrate plot would be a sharp line, as shown in Figures 6.2
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and 6.3. However, we do not see a sharp line for phosphate vs. nitrate in Figure 6.1. The implication isthat the quality of phosphate and nitrate data in previous years was not good. We discuss this issue laterin section 7. We can also see outliers in the oxygen vs. phosphate plot in Figure 6.1, but no similar
outliers appear in Figures 6.2 and 6.3. The data suggest that on some cruises in the extensive WOD
database, which contains data from many cruises, there unrecognized problems with phosphatemeasurements

Figure 6.1. 2D/3D property/property plots from 1928 to 2017

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Figure 6.2. 2D/3D property/property plots for a part of P06 line obtained during 2003 by Japanesescientists.

Figure 6.3. 2D/3D property/property plots of a part of P06 line in 2009 by U.S. scientists
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7.

History of a region, 32°–35°S and 178°–170°W, in the South Pacific Ocean: evidence ofimprovement of data quality by different organizations

Figure 7.1 shows a long-term history of reported phosphate concentration in the region bounded by
32–35°S and 170–178°W (the region of interest), in the South Pacific Ocean. We have data from 1928
to 2017. After 2003, phosphate concentrations were measured using RM or CRM. Vertical profiles inthis region obtained in 2003 and 2017 therefore showed good consistency and showed the same patterns
as vertical profiles in the region of interest (Figure 7.1), whereas vertical profiles obtained before 1980
were much more scattered, and concentrations were not consistent with those obtained after 2003. Thisis a good example of how good quality control, and especially the use of RM/CRM, can reveal more
realistic characteristics of phosphate profiles.

Figure 7.1. Reported phosphate concentration for samples collected deeper than 1900 m in the region ofinterest from 1928 to 2017
In addition to the history of phosphate concentrations, we observed that nitrate vs. phosphate for thesame region but at depths greater than 1900 meters were also scattered before 1980, whereas the molar
ratio of nitrate to phosphate of samples obtained after 2003 was almost constant at 14.32 ± 0.15 (n =901), as shown in Figure 7.2.
The good quality control procedures articulated in Chapter 4 of Volume 1 of the Guideline of Ocean
Observations surely resulted in a good quality dataset, as shown in this section as well as in the next
section 8. These high quality datasets are the basis for scientific research into how the marine
environment is changing or not. We believe that continuing to produce high quality datasets over thelong term will be the basis of our research on marine environmental and climate change.
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Figure 7.2 N:P atomic ratios based on reported nitrate and phosphate concentration for samples collected
at depths greater than 1900 m in the region of interest from 1928 to 2017.

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8. History along the P09 section: evidence of improvement of quality of data collected by thesame organization
The JMA has measured nutrient concentrations in each layer and has reported the concentrations
measured using in-house standard solutions. Since April 2010, nutrient CRMs (more than two
concentrations) have been analysed at all stations to ensure comparability between cruises and stations.
As a confirmation of the validity of the analysis, it has been confirmed that the result of the nutrient
CRM analysis, which is obtained with a home-made standard solution prepared for each measurement
station, is included in the uncertainty of the CRM certified value range. In addition, the same batch of
CRM with more than one concentration level is continuously measured between cruises to maintaincomparability between cruises. However, because the comparability is not ensured for the values given
with the in-house standard solution, even if there is a difference in the analytical value between themeasurement points and between the cruises, it is difficult to judge whether the difference depends on
the analysis error or environmental fluctuation. This section gives examples of spatial and temporalvariations of nitrate+nitrite (hereinafter referred to as nitrate), phosphate, and silicate from 1967 to 2017
along the 137°E longitude line (137°E line) monitored by the Japan Meteorological Agency. We thendiscuss the effect of ensuring traceability and comparability by correcting the values obtained with inhouse standard solutions using nutrient CRMs. Nutrient data from April 2010 onwards are based on therelationship between the CRM analysis values of 2–4 concentrations analyzed at each measurement
point and the certified values. The nutrient concentration was used after being corrected. Thereby,comparability and traceability could be ensured for the data within this period. Nutrient and dissolved
oxygen uncertainties (k = 2) were calculated by Nakano (2010).
8.1 Comparability among stations
Figure 8.1 shows the N:P ratio cross-section of the 2016 P09 (137°E) re-visited cruise. Although the
N:P ratio based on the inhouse standard solution prepared at each station did not fluctuate with depth,
there was a slight gradient in the meridional direction. However, application of the CRM that ensured
comparability among stations caused the gradient to disappear. This example means that the nutrient
concentration based on in-house standard solutions might include systematic/random errors among
stations, and the ability to perform analyses with relatively small uncertainties is not enough to ensure
accuracy. In addition, the observational results that the N:P ratio was uniformly distributed in thelatitudinal direction in the deep layer along the 137°E line was detected for the first time by using thenutrient CRM. Thus, scientific knowledge was obtained because of maintaining comparability andtraceability.

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Figure 8.1. Vertical sections of atomic N:P ratio based on (a) in-house standard and (b) CRM below
1000 m along the 137°E section in July–August 2016. Gray line indicates boundary of legs. (This figure
is reproduced from a figure in Current Situation and Future Perspective for Environmental Standards of
Seawater: Commencing with Certified Reference Materials (CRMs) for Nutrients , Umi no kenkyuu, bypermission of Oceanographic Society of Japan)
8.2 Comparability among cruises
Examination of the time series data at a depth of 2000 m, 20°–25°N of the 137°E line revealed
almost no temporal variation in dissolved oxygen concentration (Figure 8.2). This result indicates thatthe natural variability/change of dissolved oxygen at a depth of 2000 m might be small, the analyses ofdissolved oxygen concentrations have compared relatively well, and systematic errors between cruises
have been relatively small. On the other hand, there have been relatively large variations in nutrient
concentrations, especially in the data leading up to the 1980s. Considering that the Redfield ratio(N:P:O2 = 16:1:-170; Anderson and Sarmiento, 1994) is considered to reflect the average chemicalcomposition of organisms in the ocean, the temporal variation of nutrient concentrations is obviously
large. If the metric NO or PO reflects the relationship between nutrient concentrations and oxygen (NO= O2 + NO3 ∙ 170/16, PO = O2 + PO4 ∙ 170; Broecker, 1974) the Redfield ratio corrected by Anderson
and Sarmiento (1994)) showed large variations during the same period. Because NO and PO are quasipreserved components that do not change with photosynthesis or respiration, if nitrate and phosphatefluctuations depended on natural variations through biological activity, they should vary in the direction
opposite to variations of oxygen. Another possibility is that there may be a bias from the Redfield ratio
in area of interest, or the Redfield ratio and the NO and PO of the source water may change over time.
However, because the dissolved oxygen concentration did not change, it is reasonable to judge that thetemporal variation found in the old nutrient data was not a natural variation but a systematic error that
depended on the magnitude of the analytical error.

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Figure 8.2. Time series of (a) nitrate+nitrite, (b) phosphate, (c) silicate, (d) dissolved O2, (e) NO, (f) PO,(g) N:P atomic ratio, and (h) potential temperature at 2000 m at 20°–25°N along the 137°E section.
Light blue and red symbols indicate in-house standard-based and CRM-based data, respectively. Error
bars for some symbols denote uncertainty (k = 2). Arrows mean relationship of Redfield ratio among
N:P:O2 (Anderson and Sarmiento, 1994). (This figure is reproduced from a figure in Current Situation
and Future Perspective for Environmental Standards of Seawater: Commencing with Certified
Reference Materials (CRMs) for Nutrients , Umi no kenkyuu, by permission of Oceanographic Societyof Japan)
Close examination of the variation of dissolved oxygen reveals that the data after 2010 show small
fluctuations of ~5 µmol kg−1. Because the uncertainty of the oxygen measurement was small (~0.5 µmol
kg−1 (k = 2) for a dissolved oxygen concentration of 120 µmol kg−1), this variation is a statisticallysignificant difference. However, this uncertainty is based on the KIO3 standard, which is the standard
solution for oxygen analysis, and not an O2 standard itself. This variation of O2 is significantly correlatedwith the water temperature, so there is no doubt that natural variation contributes. However, a systematic
error in analysis due to the lack of comparability among stations and cruises should be considered.
Development of certified reference materials for dissolved oxygen is therefore needed to evaluate thechanges of dissolved oxygen concentration changes in an appropriate scientific manner.

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8.3 Use of nutrient CRMs
Examination of the nutrient concentration time-series data reveals that the accuracy of the analyses
has improved since the 1990s when WOCE observations were carried out (Figure 8.2). Since 2000, theaccuracy of nutrient analysis has further improved. This improvement is clear from the fact that themagnitude of temporal fluctuations in nutrients has approached that of dissolved oxygen concentrations.
Furthermore, after 2010, nutrient concentrations have been corrected with CRMs, and all nutrient
components have been consistent within uncertainty. It should be noted that the values have been
consistent not only in quasi-preserved components such as NO and PO, but also in silicates and N:P
ratios. These results indicate that there has been no significant change in nutrient concentrations or theirderived components, at least within this period. A comparison of nutrient concentration changes in the
1990s and 2000s with those after 2010 reveals that there have been changes over time, including thederived components in the 1990s and 2000s. However, comparability was not ensured before 2009
because CRMs were not used before 2009. It is therefore difficult to determine whether this change wasa natural change or the result of analytical errors. Assuming that there have been no natural variationsin the deeper layers adapted in international integrated datasets such as PACIFICA (Suzuki et al., 2013)
and GLODAP (Olsen et al., 2016), it is still possible to study changes from the epipelagic to themesopelagic, where changes may have been relatively large. However, such an analysis cannot be madeof natural variation in the bathypelagic or abyssopelagic. In addition, this method makes it difficult toevaluate the Redfield ratio. However, if we use nutrient CRMs, we do not need the offset correction todata obtained from the surface layer to the deep layer, and we can make a rigorous evaluation of the
Redfield ratio by ensuring traceability and comparability. Single chemical components as well asderived components (e.g., a quasi-preserving component such as NO) that combine multiple components
based on the Redfield ratio can be obtained accurately. It is very likely that new scientific knowledge
about the role of nutrients in the carbon cycle and climate change will be obtained.

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Acknowledgements
The authors thank for the authors of cruise reports of R/V Mirai and R/V Ryofu Maru which werecited in this article. The authors also thank Dr. T. Gamo for providing GEOTRACE post-cruise metadata.
We also thank Dr. T. Nakano and Dr. J. Swift for their suggestions and comments on this article.
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Appendix
I IOC data policy 2003
II Examples of cruise summary reportII-1 Examples of cruise summary report of
KH-09-5
II-2 Examples of post cruise metadata of thesame cruise KH-09-05 as shown above
II-3 An example of cruise summary report,
expanded version by R/V Ryofu Maru

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Appendix I: IOC data policy 2003
During its twenty-second session (24 June - 4 July 2003) the IOC Assembly adopted Resolution IOCXXII-6 entitled 'IOC Oceanographic Data Exchange Policy
RESOLUTION IOC-XXII-6(Agenda item 4.3.2 )IOC OCEANOGRAPHIC DATA EXCHANGE POLICY
The Intergovernmental Oceanographic Commission,

1

Recalling Resolution XX-11 on Oceanographic Data Exchange Policy (1999),

2

Noting:(i) WMO Resolution 40 (Cg-XII) which defined a policy and practice for the international exchangeof meteorological and related data and is intended to promote the free and unrestricted exchangeof basic data,(ii) The “Statement on Data Management Policy for Global Ocean Programmes” as submitted by the
IOC Committee on IODE (Recommendation IODE-XIV.6, December 1992) and adopted by the
IOC Assembly at its 17th Session (Paris, 25 February–11 March 1993) (para. 220 of theSummary Report of the Session),

3

Considering the reports of deliberations of:(i) The Ad hoc Working Group on Oceanographic Data Exchange Policy (Paris, 15–17 May 2000),(ii) The First Session of the Intergovernmental Working Group on IOC Oceanographic Data
Exchange Policy (Brussels, 29–31 May 2001),(iii) The Second Session of the Intergovernmental Working Group on IOC Oceanographic Data
Exchange Policy (Paris, 17–18 June 2002),

4

Adopts the IOC Oceanographic Data Exchange Policy as detailed in the Annex to this Resolution.

Financial implications: none

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ANNEX TO DRAFT RESOLUTION IOC-XXII/DR.3 IOC OCEANOGRAPHIC DATAEXCHANGE POLICY
Preamble
The timely, free and unrestricted international exchange of oceanographic data is essential for theefficient acquisition, integration and use of ocean observations gathered by the countries of the world fora wide variety of purposes including the prediction of weather and climate, the operational forecastingof the marine environment, the preservation of life, the mitigation of human-induced changes in themarine and coastal environment, as well as for the advancement of scientific understanding that makes
this possible.
Recognising the vital importance of these purposes to all humankind and the role of IOC and its
programmes in this regard, the Member States of the Intergovernmental Oceanographic Commissionagree that the following clauses shall frame the IOC policy for the international exchange ofoceanographic data and its associated metadata.
Clause 1
Member States shall provide timely, free and unrestricted access to all data, associated metadata andproducts generated under the auspices of IOC programmes.
Clause 2
Member States are encouraged to provide timely, free and unrestricted access to relevant data andassociated metadata from non-IOC programmes that are essential for application to the preservation oflife, beneficial public use and protection of the ocean environment, the forecasting of weather, theoperational forecasting of the marine environment, the monitoring and modelling of climate andsustainable development in the marine environment.
Clause 3
Member States are encouraged to provide timely, free and unrestricted access to oceanographic data andassociated metadata, as referred to in Clauses 1 and 2 above, for non-commercial use by the research andeducation communities, provided that any products or results of such use shall be published in the open
literature without delay or restriction.
Clause 4
With the objective of encouraging the participation of governmental and non-governmental marine data
gathering bodies in international oceanographic data exchange and maximizing the contribution ofoceanographic data from all sources, this Policy acknowledges the right of Member States and data
originators to determine the terms of such exchange, in a manner consistent with international
conventions, where applicable.
Clause 5
Member States shall, to the best practicable degree, use data centres linked to IODE’s NODC and WDC
network as long-term repositories for oceanographic data and associated metadata. IOC programmes will
co-operate with data contributors to ensure that data can be accepted into the appropriate systems andcan meet quality requirements.
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Clause 6
Member States shall enhance the capacity in developing countries to obtain and manage oceanographic
data and information and assist them to benefit fully from the exchange of oceanographic data,associated metadata and products. This shall be achieved through the non-discriminatory transfer oftechnology and knowledge using appropriate means, including IOC’s Training Education and Mutual
Assistance (TEMA) programme and through other relevant IOC programmes.
Definitions‘Free and unrestricted’ means non-discriminatory and without charge. “Without charge”, in the context
of this resolution means at no more than the cost of reproduction and delivery, without charge for the dataand products themselves.
‘Data’ consists of oceanographic observation data, derived data and gridded fields.
‘Metadata’ is 'data about data' describing the content, quality, condition, and other characteristics of data.
‘Non-commercial’ means not conducted for profit, cost-recovery or re-sale.
‘Timely’ in this context means the distribution of data and/or products, sufficiently rapidly to be ofvalue for a given application‘Product’ means a value-added enhancement of data applied to a particular application

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II-1: Cruise summary report of KH-09-5
Reference No.
: 20100060
Ship Name: HAKUHO MARU
Ship Type: Research Ship
Cruise No./Name: KH-09-5
Cruise Period: 2009/11/06 to 2010/01/09
Responsible Laboratory :Atmosphere and Ocean Research Institute, The University of Tokyo
Chief Scientist(s): Toshitaka Gamo, Marine Inorganic Chemistry Lab., Ocean ResearchInstitute, Univ. Tokyo
General Ocean Area(s): Indian Ocean
Geographic Coverage: 28,66,30,329,364,401,438,474,510,547,548,512,476,477,441
Project Name
: GEOTRACES
Coordinating Body
: SCOR, Atmosphere and Ocean Research Institute (Univ. Tokyo)
Principal Investigators : A;Toshitaka Gamo the University of Tokyo: B; Yoshihisa Kato Tokai University: C; Yoshifumi Nogi National Institute of Polar Research: D; Toshio Suga JAMSTEC: E; Yuko Takahashi Senshu University
Objectives and Brief Narrative of Cruise:This cruise has been internationally authorized as the first GEOTRACES meridional study in
the Indian Ocean. GEOTRACES means an international study of the marine biogeochemical cyclesof trace elements and their isotopes (TEIs) in a global scale. The determination of traceelements has recently become a central focus of many research programs that seek informationon the biogeochemical processes in the ocean. The study of TEIs has graduated from a curiosity
to understand how the chemical diversity of trace elements, in their various redox andchemical states, interacts with the physical and biological processes occurring in the ocean.
This is particularly important in the case of micronutrients such as Fe, whose oceanic
distributions seem to be a crucial link to climatic processes. Together with otherbiologically required TEIs, perturbations of their cycles induced by the climate change may
have fundamental consequences for the global carbon cycle, which is firmly associated with
global climate. Although our knowledge on the behavior of TEIs in the ocean is fairly small
at the present stage, recent advances on analytical and clean sampling techniques have justenabled us to get precise information on TEIs in the ocean, which is the powerful backgroundto initiate a new international program, GEOTRACES. As the GEOTRACES initiative in the Indian
Ocean, the main study theme of this cruise was marine geochemical observations in thenorthern (chiefly in the Bengal Bay) and western Indian Ocean from the Arabian Sea to the
Antarctic Sea along a meridional line. Our ability to predict the future environmental change
caused by the global warming depends upon knowledge on the distribution of biologicallyimportant chemical species in the ocean and their exchange flux at the air-sea and sedimentwater interfaces. The Indian Ocean occupies a vast area of the world ocean, but little is
known about the marine biogeochemical cycles on TEIs. Thus, it is important to understandthe role of the Indian Ocean in the global carbon cycle including its temporal variations
recorded in marine sediments.
Moorings,Bottom Mounted Gear and Drifting Systems:
PI LAT.
LON.
DATATYPEDESCRIPTION
D 30-.1:S 64-59.5:
Argo float
D 37-45.4 57-36.8:
Argo float
D 44-20:S 28-55.3:
Argo float
Summary of Measurements and Samples Taken:
PI
NO
UNITS DATATYPEDESCRIPTION
A
12
station H09,H10,H11,H16,H21,H22,H Seabird Carousel-32 Multi BottB
11
core G04
Surface sediment (20~40 cm deB2core G04
Sediment core samples (~15 m)C
9station H10,H13
XBTs and XCTDs
C
1
track G27,G74
Underway geophysical measurement
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II-2: Post cruise metadata of the cruise KH-09-05
KH-09-5 cruise leg-1, 2, and 3
Cruise Name: [any identifier (acronyms),
Including technical name]Platform Name and type: Research Vessel Hakuho Maru
[vessel, mooring, satellite,, towed vehicle,]
Project: GEOTRACES Indian Ocean[associated project or program name related to funding]Lead Nation: Japan
Chief scientist (Lead scientist / Principal Investigator) contact details
Name: Toshitaka Gamo

Email:

Phone:

Mailing Address:
Ocean Research Institute, the University of Tokyo
1-15-1 Minamidai, Nakano-ku, Tokyo 161-8639 (JAPAN)
Co-Chief scientist contact details: [GEOTRACES point of contact if different from Chief scientist]
Name:

Email:

Phone:

Mailing Address:
Cruise Details
Start Port and Country: Tokyo, Japan

Start date: November 6, 2009

End Port and Country: Cape Town, South Africa

End Date: January 10, 2010

Location: [general description of study area; map if possible]
Indian Ocean, Antarctic Sea (cruise track is shown in the attached map)
Cruise Overview: [proposal abstract]
The KH-09-5 Cruise leg-1, -2, and -3 of R/V Hakuho Maru was planned to pursue Trace Element Oceanography inJapan as part of the international project SCOR-GEOTRACES (study of the marine biogeochemical cycles of traceelements and isotopes). The cruise aimed at precise and detailed measurements of trace elements and isotopes in the
Indian Ocean including the atmosphere and bottom sediment, in order to identify processes and fluxes that control the
distribution of trace elements in water columns, and to elucidate their important linkage with the global climatic change.
We collected seawater, air, plankton and sediment samples for the measurement of trace elements including the
GEOTRACES key parameters, dissolved gases, stable- and radio-isotopes at 12 locations chiefly along meridional lines(~65°E and ~30°E) in the western Indian Ocean and the Antarctic Sea.
Intercalibration activities: Please provide details of how each element was calibrated to meet therequirements of the GEOTRACES programme e.g. use of SaFe standards, collaborative sampling.
For small- volume elements (Fe, Al, Zn, Mn, Cd, Cu, Co, Pb), analysts will use the SaFe standards to verify their own
methods. For large-volume elements (230Th, 231Pa and Nd isotopes), analysts will reveal vertical profiles of theseelements at the baseline station in Arabian Sea (15 N, 65 E), recommended in the GEOTRACES Intercalibration
Planning Document. A subset of samples collected at the baseline station will be distributed to GEOTRACES
collaborators for analyses and verification of accuracy.
We took two sets of clean samples for comparison between the usual CTD hydrocast with Ti armored cable and thespecial hydrocast using Kevlar wire at two stations ER-3 and ER-10.
List of parameters to be submitted to GDAC: Key parameters listed, please list any other parameters
measured and the PI’s contact information. Also include information in regards to the phase i.e. dissolved or
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particulate and how the samples were collected. i.e. Fe (dissolved)- CTD –Bottle or Fe (dissolved) –Insitu
pumps.
Could PI provide information on when samples are expected to be analysed so GDAC can estimate
data delivery date.
Trace elements: Contact for each element (PI); [name and InternationallyExpected datecalibrated (Yes or of analysis
email]FeNo)
J. Nishioka
AlYes
Y. Sohrin
Zn
Yes
Y. Sohrin
Mn
Yes
Y. Sohrin
Cd
Yes
Y. Sohrin
Cu
Yes
Y. Sohrin
Other
Yes
Other
Other
Radioactive
isotopes:
230
Th
231
Pa
Other
Other
Other
Other

A. Okubo
A. Okubo

Stable isotopes:
U. Tsunogai
δ15Ν
13
Y. Kumamoto
δ C
Other
Radiogenic
isotopes:
Nd isotopes
Pb isotopes
Other

H. Amakawa
and H. Tazoe
E. Boyle

Yes
Yes

Yes
Yes

Yes
Yes

NON TEI dataset (add as
required)

Other parameters:
Se: Y. Nakaguchi
Cr: K. Isshiki
14
C: Y. Kumamoto
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List CTD hydrographic parameters [sensors including make; salinity, temperature, oxygen, nutrients etc]
Carousel Multi-bottle sampler (SBE-32)
Sea-Bird’s 911 plus CTD (salinity, temperature, oxygen, fluorescence, light transimission)
Particles/Aerosols: Sampled
List Underway data: [Met data, navigation hull mounted sensors including make and model]
Is there a national data centre: (name and contact) [If not GDAC should be used]
JODC (Japan Oceanographic Data Center; http://www.jodc.go.jp/index.html) will serve as the national data
center for GEOTRACES in Japan. The contact person is Mr. Akihiro SETA .
Other relevant information:

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II-3: Cruise summary report, expanded version by R/V Ryofu MaruCRUISE REPORT: P03W
(Updated AUG 2018)

Highlights
Cruise Summary Information
P03W (RF13-06, RF13-07)
49UP20130619
Kazuhiro NEMOTO
Chief Scientists
Hitomi KAMIYA
Dates 2013-06-24 to 2018-09-18
Ship Ryofu Maru
Ports of call Naha, Japan - Tokyo, Japan30° 14.59' N
126° 26.85' E
179° 3.76' E
Geographic Boundaries
23° 42.63' N
Stations 120
Floats and drifters deployed
1 float and 2 drifting ocean data buoys
Moorings deployed or recovered
0
Contact Information:
Kazuhiro NEMOTO
Hitomi KAMIYA
Marine Division • Global Environment and Marine Department • Japan Meteorological Agency(JMA) 1-3-4, Otemachi, Chiyoda-ku, Tokyo 100-8122, JAPAN
Phone: +81-3-3212-xxxx Ext. xxxx
Section Designation
Expedition designation (ExpoCodes)

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A. Cruise narrative
1. Highlights
Cruise designation: RF13-06 and RF13-07 (WHP-P03W revisit)a. EXPOCODE: 49UP20130619
b. Chief scientist: RF13-06 Kazuhiro NEMOTO
c. RF13-07 Hitomi KAMIYA
Marine Division
Global Environment and Marine Department Japan Meteorological Agency(JMA)
1-3-4, Otemachi, Chiyoda-ku, Tokyo 100-8122, JAPAN
Phone: +81-3-3212-ｘｘｘｘ

Ext. ｘｘｘｘ

d. Ship name: R/V Ryofu Marue. Ports of call: RF13-06 Leg 1: Tokyo–Naha, Leg 2: Naha–Tokyo RF13-07 Leg
1: Tokyo–Pohnpei, Leg 2: Pohnpei–Tokyo

f. Cruise dates: RF13-06 Leg 1: 19 June 2013–1 July 2013 RF13-06

Leg 2: 5 July 2013–24 July 2013 RF13-07 Leg 1: 31
July 2013–21 August 2013
RF13-07 Leg 2: 25 August 2013–18 September 2013

g. Floats and drifters deployed: RF13-06: 1 float and 2 drifters
2. Cruise Summary Information

RF13-07: 5 floats

RF13-06 and RF13-07 cruises were carried out during the period from June 19 to September 18,
2013. The observation line along approximately 24°N was observed by Scripps Institution of
Oceanography (SIO), USA in 1985 and Japan Agency for Marine-Earth Science and Technology(JAMSTEC), Japan in 2005–2006. These cruises were carried out as ‘WHP-P03’, which is a part of
WOCE (World Ocean Circulation Experiment) Hydrographic Programme, CLIVAR (Climate
Variability and Predictability Project) and GO-SHIP (Global Ocean Ship-based Hydrographic
Investigations Program).
A total of 120 stations was occupied using a Sea-Bird Electronics (SBE) 36 position carousel
equipped with 10-liter Niskin water sample bottles, a CTD system (SBE911plus) equipped with
SBE35 deep ocean standards thermometer, JFE Advantech oxygen sensor (RINKO III), Teledyne
Benthos altimeter (PSA-916D), and Teledyne RD Instruments L-ADCP (300kHz). Cruise track andstation location are shown in Figure 1.
At each station, full-depth CTDO2 (temperature, conductivity (salinity) and dissolved oxygen)profile and up to 36 water samples were taken and analyzed. Water samples were obtained from 10
dbar to approximately 10 m above the bottom. In addition, surface water was sampled using a
stainless steel bucket at each station. Sampling layer is designed as so-called staggered mesh as shown
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in Table 1 (Swift, 2010). The bottle depth diagram is shown in Figure 2.
Water samples were analyzed for salinity, dissolved oxygen, nutrients, dissolved inorganic carbon(DIC), total alkalinity (TA), pH, CFC-11, CFC-12 and phytopigment (chlorophyll-a andphaeopigments). Underway measurements of partial pressure of carbon dioxide (pCO2), temperature,salinity, chlorophyll-a, subsurface current, bathymetry and meteorological parameters were conductedalong the cruise track.
RF13-06
RF13-06 cruise was carried out during the period from June 19 to July 24, 2013. Before theobservation at the first station, all watch standers were drilled in the method of sample drawing
and CTD operations at the point (34°22’N, 138°30’E). At first, the cruise started from Stn.13(28°42’N, 126°27’E; RF4757) and sailed south-eastward to Stn.26 (27°30’N, 128°15’E; RF4770).
After observation of Stn.26 we observed from Stn.1 (30°14’N, 130°50’E; RF4771) to Stn.12(28°35’N, 129°45’E; RF4782) and from Stn.27 (26°04’N,
127°55’E; RF4783) to Stn.31 (25°39’N, 128°34’E; RF4787). Leg 1 consisted of 31 stations. We
finished Stn.31 on June 29. She called for Naha (Japan) on July 1 (Leg 1). She left Naha on July 5,
we restarted observation from Stn.32 (25°39’N, 128°34’E; RF4788) that was same the station of Stn.31.
Owing to the typhoon (T1307), after observation of Stn.45 (23°43’N,
133°00’E; RF4801), we sailed to Stn.63 (24°15’N, 143°38’E; RF4802). After observation of Stn.63,
we sailed to westward, and observed from Stn.59 (24°14’N, 141°34’E; RF4803) to Stn.52 (24°15’N,
137°47’E; RF4810). We gave up at the station of Stn.52 and turned toward Tokyo (Japan). Leg 2
consisted of 23 stations. We arrived at Tokyo on July 24, 2013 (Leg 2).
One float and two drifting ocean data buoy were deployed along the cruise track. The informationof deployed the float and the buoy are listed in Table 2a.
RF13-07
RF13-07 cruise was carried out during the period from July 31 to September 18, 2013. Before theobservation at the first station, all watch standers were drilled in the method of sample drawing and
CTD operations at the point (34°41’N, 139°51’E). We restarted observation from Stn.46 (24°14’N,
133°21’E; RF4812) on August 3 to Stn.51 (24°14’N, 137°49’E; RF4817)
that was same the station of Stn.52, and from Stn.60 (24°15’N, 141°46’E; RF4818) and Stn.62(24°15’N, 143°14’E; RF4820). We continued observation from Stn.64 (24°15’N, 143°39’E; RF4821)
that was the same station of Stn.63. We sailed eastward and finished at Stn.89 (24°00’N, 164°59’E;
RF4846) on August 15. Leg 1 consisted of 35 stations. She called for Pohnpei (Federated States ofMicronesia) on August 21 (Leg 1). She left Pohnpei on August 25, 2013. The hydrographic castof CTDO2 was restarted at the same station (Stn.90 (24°00’N, 165°01’E; RF4847)) of Stn.89 on
August 28. We observed eastward to Stn.108 (24°00’N, 179°00’E; RF4865), we turned northward
and finished Stn.120 (29°58’N, 178°58’E; RF4877). Leg 2 consisted of 31 stations from Stn.90
to Stn.120. Stn.120 was finished on September 7. She arrived at Tokyo (Japan) on September 18, 2013
(Leg 2).
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Five Argo floats were deployed along the cruise track. The information of deployed the float andthe buoy are listed in Table 2b.
Location data of stations is shown in Table 3.

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Figure 1: Cruise track of RF13-06 and RF13-07.

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Figure 2: The bottle depth diagram for WHP-P03 revisit.

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Table 1. The scheme of sampling layer in meters.
Bottle count
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36

scheme1
10
50
100
150
200
250
300
400
500
600
700
800
900
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3250
3500
3750
4000
4250
4500
4750
5000
5250
5500
5750
6000

scheme2
10
50
100
150
200
250
330
430
530
630
730
830
930
1070
1270
1470
1670
1870
2070
2270
2470
2670
2870
3080
3330
3580
3830
4080
4330
4580
4830
5080
5330
5580
5830
6000

scheme3
10
50
100
150
200
250
280
370
470
570
670
770
870
970
1130
1330
1530
1730
1930
2130
2330
2530
2730
2930
3170
3420
3670
3920
4170
4420
4670
4920
5170
5420
5670
6000

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Table 2a. Information of deployed float and buoy at RF13-06.
Float

Date and Time (UTC)

Position of deployment

WMO numberof Deployment
2013 July 9
01:32
Date and Time (UTC)

LatitudeLongitude

23-42.54 N

132-56.59 E

of Deployment
2013 June 25
01:32
2013 July 600:42

28-42.30 N
25-32.74 N

2902430
Buoy
WMO number
21679
21704

PI
JMA

APEX

126-27.04 E

JMA

YTSS-2100

128-44.72 E

JMA

YTSS-2100

Position of deployment
LatitudeLongitude

APEX：Teledyne Webb Research (USA)YTSS-2100: JVC KENWOOD Co., Japan
Table 2b. Information of deployed float and buoy at RF13-07.
Float
WMO number
29024532902461290246229024632902464

Date and Time (UTC)of Deployment
2013 August 12
05:30
2013 August 29
21:59
2013 August 31
20:45
2013 September 2
11:45
2013 September 3
10:20

Position of deployment
LatitudeLongitudePI

24-16.70 N

157-39.46 E

JAMSTEC

ARVOR

24-16.84 N

168-02.16 E

JAMSTEC

ARVOR

24-18.38 N

172-47.57 E

JAMSTEC

ARVOR

24-16.08 N

176-47.13 E

JAMSTEC

ARVOR

24-00.89 N

178-59.85 E

JAMSTEC

ARVOR

ARVOR：nke Instrumentation (France)

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Table 3a. Station data of RF13-06 cruise. The ‘RF’ column indicates the JMA station
identification number.
EXPOCODE Leg
Stationsub number
Stn. RF
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4783
4784
4785
4786
4787
4788
4789
4790
4791

Position
LatitudeLongitude
30-14.47 N
30-05.87 N
29-58.18 N
29-48.88 N
29-40.04 N
29-32.26 N
29-23.21 N
29-15.26 N
29-06.58 N
28-58.18 N
28-50.25 N
28-35.19 N
28-42.01 N
28-38.37 N
28-33.26 N
28-29.59 N
28-24.62 N
28-21.11 N
28-16.09 N
28-10.72 N
28-06.17 N
28-02.56 N
27-57.76 N
27-48.18 N
27-38.76 N
27-30.08 N
26-04.15 N
26-00.11 N
25-54.71 N
25-47.16 N
25-39.13 N
25-38.74 N
25-29.81 N
25-20.88 N
25-09.31 N

130-50.26 E
130-44.66 E
130-40.29 E
130-34.72 E
130-28.82 E
130-23.37 E
130-17.82 E
130-12.34 E
130-06.60 E
130-01.36 E
129-55.28 E
129-45.09 E
126-26.87 E
126-34.13 E
126-41.28 E
126-48.44 E
126-54.41 E
127-01.79 E
127-08.65 E
127-14.80 E
127-21.50 E
127-28.39 E
127-34.77 E
127-48.09 E
128-02.00 E
128-15.29 E
127-54.85 E
128-02.11 E
128-09.77 E
128-21.45 E
128-33.96 E
128-33.71 E
128-43.41 E
129-00.74 E
129-14.70 E

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Table 3a. Continue.
EXPOCODE Leg
Stationsub number
Stn. RF
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

36
37
38
39
40
41
42
43
44
45
52
53
54
55
56
57
58
59
63

4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4810
4809
4808
4807
4806
4805
4804
4803
4802

Position
LatitudeLongitude
24-59.45 N
24-50.65 N
24-40.71 N
24-28.09 N
24-14.71 N
23-59.02 N
23-45.49 N
23-45.05 N
23-45.30 N
23-43.71 N
24-14.55 N
24-15.12 N
24-14.40 N
24-13.83 N
24-14.62 N
24-14.60 N
24-14.47 N
24-14.07 N
24-15.23 N

129-29.38 E
129-44.33 E
129-58.82 E
130-19.53 E
130-38.28 E
130-58.98 E
131-28.65 E
131-59.11 E
132-29.45 E
133-00.00 E
137-47.36 E
138-33.99 E
139-26.01 E
140-14.17 E
140-46.37 E
141-11.02 E
141-23.34 E
141-33.75 E
143-37.66 E

Table 3b. Station data of RF13-07 cruise. The ‘RF’ column indicates the JMA station
identification number.
Leg
EXPOCODE
sub number
3
3
3
3
3
3
3
3
3
3
3

1
1
1
1
1
1
1
1
1
1
1

StationPosition

Stn.

RF

LatitudeLongitude

46
47
48
49
50
51
60
61
62
64
65

4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822

24-13.57 N
24-14.06 N
24-15.17 N
24-15.03 N
23-59.27 N
24-14.25 N
24-15.40 N
24-15.84 N
24-15.32 N
24-15.11 N
24-15.63 N

133-21.00 E
133-59.75 E
134-59.94 E
136-12.54 E
137-00.24 E
137-48.60 E
141-45.91 E
142-26.98 E
143-13.93 E
143-38.58 E
144-50.93 E

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Table 3b. Continue.
EXPOCODELegsub number

StationPosition

Stn.

RF

LatitudeLongitude

3

1

66

4823

24-14.65 N

146-03.68 E

3

1

67

4824

24-15.78 N

147-15.35 E

3

1

68

4825

24-15.50 N

148-28.09 E

3

1

69

4826

24-14.47 N

149-01.46 E

3

1

70

4827

24-16.36 N

149-39.23 E

3

1

71

4828

24-17.59 N

150-30.54 E

3

1

72

4829

24-14.47 N

151-14.05 E

3

1

73

4830

24-16.08 N

152-02.72 E

3

1

74

4831

24-16.71 N

152-49.03 E

3

1

75

4832

24-16.19 N

153-33.69 E

3

1

76

4833

24-10.97 N

154-26.25 E

3

1

77

4834

24-14.91 N

155-12.52 E

3

1

78

4835

24-14.85 N

156-03.86 E

3

1

79

4836

24-15.89 N

156-50.46 E

3

1

80

4837

24-15.92 N

157-39.77 E

3

1

81

4838

24-15.76 N

158-27.00 E

3

1

82

4839

24-14.67 N

159-14.71 E

3

1

83

4840

24-14.30 N

160-04.14 E

3

1

84

4841

24-14.98 N

160-50.69 E

3

1

85

4842

24-15.82 N

161-35.29 E

3

1

86

4843

24-15.13 N

162-26.54 E

3

1

87

4844

24-15.55 N

163-16.16 E

3

1

88

4845

24-15.36 N

164-03.30 E

3

1

89

4846

24-00.15 N

164-59.37 E

4

2

90

4847

24-00.48 N

165-00.85 E

4

2

91

4848

24-15.67 N

165-42.12 E

4

2

92

4849

24-16.16 N

166-31.51 E

4

2

93

4850

24-15.57 N

167-15.59 E

4

2

94

4851

24-15.88 N

168-00.59 E

4

2

95

4852

24-15.95 N

168-46.09 E

4

2

96

4853

24-14.85 N

169-30.85 E

4

2

97

4854

24-14.74 N

170-21.82 E

4

2

98

4855

24-16.58 N

171-10.76 E

4

2

99

4856

24-15.76 N

171-55.30 E

4

2

100

4857

24-16.08 N

172-44.98 E

4

2

101

4858

24-15.52 N

173-36.53 E

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Table 3b. Continue.
EXPOCODE Leg
Stationsub number
Stn. RF
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4

2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120

4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877

Position
LatitudeLongitude
24-16.26 N
24-16.23 N
24-16.94 N
24-15.37 N
24-14.52 N
24-15.14 N
24-00.31 N
24-30.64 N
25-01.28 N
25-31.64 N
26-01.69 N
26-30.91 N
27-01.13 N
27-30.64 N
27-59.88 N
28-30.42 N
29-00.36 N
29-29.78 N
29-58.17 N

174-25.87 E
175-10.65 E
175-59.98 E
176-45.70 E
177-35.05 E
178-24.54 E
179-00.35 E
178-58.68 E
178-58.69 E
178-59.31 E
178-59.23 E
178-58.88 E
178-59.51 E
179-00.24 E
179-00.67 E
178-59.89 E
179-01.84 E
179-01.18 E
178-57.70 E

List of Principal Investigators for all Measurements
The principal investigator (PI) and the person in charge responsible for major parameters
measured on the cruise are listed in Table 4a (RF13-06) and Table 4b (RF13-07).
Table 4a. List of principal investigator and the person in charge on the ship for RF13-06.
Item
Principal Investigator（PI） Person in charge on the ship
Hydrography
CTDO2 / LADCP
Toshiya NAKANO
Tomoyuki KITAMURA
SalinityToshiya NAKANO
Sho HIBINO
Dissolve oxygen
Toshiya NAKANOTakashi MIYAO
Nutrients
Toshiya NAKANO
Sonoki IWANO
Phytopigment
Toshiya NAKANONaoshi KUBO
DIC
Toshiya NAKANO
Kyoichi KAWAHARA
Total Alkalinity
Toshiya NAKANO
Kyoichi KAWAHARA
pH
Toshiya NAKANO
Kyoichi KAWAHARA
CFCs
Toshiya NAKANO
Akira WADA
Underway
Meteorology
Toshiya NAKANO
Thermo-Salinograph Toshiya NAKANO

Kazuhiro NEMOTO
Kyoichi KAWAHARA

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pCO2
Chlorophyll-a
ADCP
Bathymetry

Toshiya NAKANO
Toshiya NAKANO
Toshiya NAKANO
Toshiya NAKANO

Float and Buoy
Argo float (JMA) Kazuhiro NEMOTO
Buoy (JMA)
Kazuhiro NEMOTO

Kyoichi KAWAHARANaoshi KUBO
Tomoyuki KITAMURA
Tomoyuki KITAMURA
Kazuhiro NEMOTO
Kazuhiro NEMOTO

Table 4b. List of principal investigator and the person in charge on the ship for RF13-07.
Item
Principal Investigator（PI） Person in charge on the ship
Hydrography
CTDO2 / LADCP Toshiya NAKANO
Kiyoshi MURAKAMI
SalinityToshiya NAKANO
Keizo SHUTTA
Dissolve oxygen Toshiya NAKANO
Hiroyuki FUJIWARA
Nutrients
Toshiya NAKANO
Chihiro KAWAMURA
Phytopigment
Toshiya NAKANOTomohiro UEHARA
DIC
Toshiya NAKANO
Shu SAITO
Total Alkalinity Toshiya NAKANO
Shu SAITO
pH
Toshiya NAKANO
Shu SAITO
CFCs
Toshiya NAKANO
Etsuro ONO
Underway
Meteorology
Thermo-Salinograph
pCO2
Chlorophyll-a
ADCP
Bathymetry

Toshiya NAKANO
Toshiya NAKANO
Toshiya NAKANO
Toshiya NAKANO
Toshiya NAKANO
Toshiya NAKANO

Float
Argo float (JAMSTEC)

Shigeki HOSODA

Hitomi KAMIYA
Shu SAITO
Shu SAITO
Tomohiro UEHARA
Keizo SHUTTA
Keizo SHUTTA
Hitomi KAMIYA

Toshiya NAKANO (ｘｘｘ@ｘｘｘ.kishou.go.jp)
Marine Division, Global Environment and Marine Department, JMA
Otemachi, Chiyoda-ku, Tokyo 100-8122, JAPAN
Phone: +81-3-3212-ｘｘｘｘ Ext. ｘｘｘｘ

1-3-4,

Kazuhiro NEMOTO (ｘｘｘ@ｘｘｘ.kishou.go.jp)
Marine Division, Global Environment and Marine Department, JMA
Otemachi, Chiyoda-ku, Tokyo 100-8122, JAPAN
Phone: +81-3-3212-ｘｘｘｘ Ext. ｘｘｘｘ

1-3-4,

Shigeki HOSODA (ｘｘｘｘ@jamstec.go.jp)
Ocean Circulation Research Group,

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Research and Development Center for Global Change (RCGC), Strategic Researchand Development area,
Japan Agency for Marine-Earth Science and Technology (JAMSTEC) 2-15
Natsushima, Yokosuka-shi, Kanagawa 237-0061, JAPAN
Reference
Swift, J. H. (2010): Reference-quality water sample data: Notes on acquisition, record keeping, andevaluation. IOCCP Report No.14, ICPO Pub. 134, 2010 ver.1

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Data Publication and International Exchange‫ۑ‬Toru SUZUKI (Marine Information Research Center, Japan Hydrographic Association),
Yutaka MICHIDA (Atmosphere and Ocean Research Institute, the University of Tokyo)

1. Introduction
Oceanographic data show observational values, which are attached to dates, times, and positions.
Recent developments and improvements to observational techniques and instruments have been
associated with data accuracy and quality control, so that the importance of the related information
increases the exchange, sharing and integration of oceanographic data. This chapter therefore
describes a mechanism of international exchange and sharing in the ocean sciences and other sciencefields for oceanographic data observed by research vessels and other ships. In this chapter, ‘data’
includes observed data and related information; the latter indicates ‘metadata’ – data of data – ifneeded. Specimens such as marine organisms or sea bottom materials are also included in data but
only numerical data are treated in this chapter.

2. Importance of Data Publication
There is no doubt about the importance of data for all scientific research. Working Group on
Scientific Data Network Facilitation (2004) expressed that geophysics is a subject which studies theaccumulation of unexpected and not replicable phenomena on the earth and vicinities since 4.6 billion
years ago, so as many continuous observations as possible are required, all records should be archived
and collected in principle and left as the common heritage of mankind. What is true for geophysics istrue for the marine sciences as well. UNESCO’s IOC established the IODE in 1961 because common
understanding in the world through oceanographic data exchange and sharing among the member
states is important.

3. Outline of Data Publication and International Exchange
The result of various observations by research vessels, including training, survey, chartered andvoluntary ships, is published by a chief scientist or someone who belongs to an organization (hereafter,
data originator) as cruise reports through preliminary and cruise summary reports. Real time data isreported before publication of their reports. In the past, observed data were recorded on paper as an
expression in numerical form of visual observations, while more recently, massive amounts of digital
data are being stored directly on mass storage devices, such as optical-magnetic disks or flash memory,for developing instruments and improving accuracy. Moreover, observed data is directly distributed bydata originators with the spread of the network system, i.e., full-time connection and unlimited accessto the Internet, and cruise reports are also outputted in digital document formats such as PDF.
The NODC, established under a program of the IODE of the IOC/UNESCO, has the role of

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providing national oceanographic data and information in a usable format to a wider user communityand for international exchange. The JODC was established in the Hydrographic Department of theJapan Maritime Safety Agency (presently, the Hydrographic and Oceanographic Department of theJapan Coast Guard) in 1965 in accordance with a resolution adopted by the IOC/UNESCO in 1961 as
well as reports from the Council for Marine Scientific Technology in 1963 and 1964. The JODC
provides various oceanographic data through its JODC Data On-line Service System (J-DOSS) andalso submits its data to the NCEI (formerly, National Oceanographic Data Center of the United States)
which houses the World Data Center for Oceanography under the ICSU WDS according to an IODE
recommendation of the WOD project. Japanese data occupy 11% of total observations in the WOD,
placing Japan second of 96 countries for contributions. Long time archiving is also one of the roles of
the NODC in order to prevent data loss by principle investigator transfer or retirement, or the
discontinuance of data distribution or archiving in his/her organization due to various reasons.
Particularly in Japan, it is necessary to pay attention to the potential of lost data and information due toa natural disaster such as an earthquake or tsunami. It is therefore strongly recommended to submit the
published data and metadata to the JODC.
On the other hand, several data management offices of international projects have continued tocollect specific data and information after the end of the projects. The CDIAC Ocean Carbon DataManagement Project was organized in 1993 and collects discrete and underway measurements ofocean carbon dioxide from various platforms, e.g., research vessels, commercial and volunteer ships,
and buoys. The CCHDO delivers the highest quality global CTD and hydrographic data, including
ocean carbon dioxide and its related parameters, which have been acquired during WOCE, CLIVAR
and other international oceanographic research programs. The OBIS was created as the information
component of the Census of Marine Life and serves to document the ocean’s diversity, distribution
and abundance of life, and is one of the projects of the IODE at the present. These data management
offices target specific parameters and therefore should be called special data centers, against the
NODC which collects all oceanographic data. The IODE cooperates with the special data centers fordata collection and distribution, and recommends registering as an ADU, a new component of the
IODE similar to the NODC. The Japan Ocean Biogeographic Information System Center of
JAMSTEC is a Japan regional OBIS node that was registered as an ADU of the IODE in January 2015.
It is also recommended that data originators submit their own data to the special data centers at thesame time. As for the ICSU World Data System, the IODE is a network member, and someorganizations in IOC member states are regular members: the World Data Service for Oceanography
in the United States, the World Data Center for Oceanography in NODCs in China and the RussianFederation, the Flanders Marine Institute, the Data Centre in Belgium, and Ocean Networks Canada.

4. National Oceanographic Programs and Cruise Summary Reports
As complementary information until the Cruise Report is published, it is recommended that NOPs
and CSRs be submitted.
A NOP provides information on when, where and what kind of oceanographic cruises are planned
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at domestic research organizations, in order to enhance the effective use of oceanographic research
opportunities and oceanographic data. NOPs are registered and searched on the Marine Information
Clearing House Network operated by the Hydrographic Department of the Japan Coast Guard. Pleasesee http://www.mich.go.jp/ for more information.
A CSR is intended to fill the gap between the first announcement of an oceanographic program
and the eventual catalogue of data available to users. As timely inventories of data to ensure prompt
exchange, the CSR contains such information as the ocean area where the investigation was carriedout, a track chart of the cruise, the name of the person who holds the data, and the name and volume ofthe data written in the IOC’s CSR form. Please see http://www.jodc.go.jp/info/csr.html for more
information.

5. Standardization for Oceanographic Data Exchange
The JODC collects oceanographic data from domestic research institutes and submits them to the
NCEI every year. Those data are stored in the WOD. In addition, non-Japanese data are extracted fromthe WOD and registered to J-DOSS all together. Recently, oceanographic data and informationexchange is being carried out for not only oceanography but also marine meteorology. The IOC
established JCOMM in cooperation with the WMO in 1999, and JCOMM coordinates, and develops
and recommends standards and procedures for, a fully integrated marine observing, data management
and services system. In order to standardize data processing, formats and codes are required for
promoting data and information exchange between researchers in oceanography and other sciences.
The Task Team for Ocean Data Standards established under the Joint JCOMM/IODE Expert Team on
Data Management Practices reviews the proposals for standardization of oceanographic data exchange
practices, and accepted proposals are recommended and published in the IOC Manuals and Guides No.
54 series. At present, three recommendations have been published for country codes, representation ofdate and time, and a quality flag scheme. It would be useful if data originators would consider theabove recommendations when publishing data.
5-1. Country Codes
Adoption of ISO 3166-1 and 3166-3 is recommended for identifying countries (IOC, 2010). Japanis defined as JP and JPN in ISO 3166-1 alpha-2 and alpha-3, respectively. The former is known as a
top level domain at the highest level in the hierarchical Domain Name System of the Internet, and thelatter is often seen in broadcasts of games or events such as the Olympics and international soccer
matches.
5-2. Representation of Date and Time
Adoption of ISO 8601:2004 is recommended for representation of date and time (IOC, 2011). The
basic date notation is YYYYMMDD, where YYYY is the year, MM is the month of the year between
01 (January) and 12 (December), and DD is the day of the month between 01 and 31 (e.g., 20150624
or 2015-06-24), and the time notation is hhmmss, where hh is the number of complete hours between
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00 and 24 (note that 24 is only allowed to indicate the end of the calendar day), mm is the number ofcomplete minutes between 00 to 59, and ss is the number of complete seconds between 00 and 60(note that 60 is used to indicate a positive leap second; e.g., 141531 or 14:15:31). The recommended
representation is therefore familiar to Japanese. For more examples, see IOC (2011). The time zone
must be clearly specified. In particular, biological observation during a long voyage or transoceanic
cruise often uses the ship’s time, not JST or GMT, in order to distinguish between day and night, so it
is difficult to standardize the date and time for data exchange.
5-3. Quality Flag Scheme
Although development and improvement of observational techniques and instruments earn wider
observation coverage and accurate data and information, it is difficult to avoid the inclusion of error
data derived from the malfunction of instruments, and missing or failed measurements. Quality control
by data originators is highly reliable and their results are extremely helpful for data exchange. Afterthe error data are eliminated or flagged as ‘bad data’ by data originators in advance, doubtful data aredetected through quality control by data centers or users and are flagged as ‘questionable data’. Someof the questionable data will be changed to ‘unknown data’ if it is difficult to make a decision because
there is little historical data and a lack of metadata. It is not to be denied that for observational records
of unexpected and not replicable phenomenon, all data should be archived and published with quality
flags. It is noted that missing value which has no missing flag, and vice versa, may be misunderstoodfor data processing.
There are many observed data exchange formats with quality flags, e.g., the WHP-exchange
format (Swift and Diggs, 2008) is the de facto standard format for CTDs and bottle sampling data withnine level quality flags added by data originators. On the other hand, data center formats, such as the
WOD and FETI of the J-DOSS, determine their own quality flags to header information and observed
data in each depth, respectively, because historical data usually have no information for data quality.
The problem here is that there is a different definition of the flags in each format, e.g., flag ‘0’ means
good in one format but flag ‘2’ means good in another format. For that reason, the recommended
quality flag scheme (IOC, 2013) defines five flags: 1 as good, 2 as unknown, 3 as questionable, 4 as
bad, and 9 as missing at the primary level, and other results for quality control procedures or dataprocessing in detail are described at the second or lower level. The other purpose for the above
simplified quality flag scheme is to promote data exchange between researchers in oceanography andother sciences. There is no format which adopts this quality flag scheme at present, but the Ocean Data
View (ODV; Schlitzer, 2015) defines quality flags similar to the primary level flags of the above
scheme, and the ODV can import 14 different existing formats with its own quality flags.
5-4. Ship Codes and Cruise Numbers
There is no proposal for standardization of ship codes and cruise numbers at present, but a de facto
standard that has been adopted by several data centers exists. It facilitates the management of observed
data and metadata from each cruise, so ship codes and cruise numbers are required to identify thecruises. A cruise number assigned by a data originator is a primary, compatible identification of a
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cruise by a ship with a timeline. For example, a cruise from September 23 to October 3 by the Ryofu
Maru of the JMA is assigned as RF14-08, where RF is the ship code from the JMA, 14 means the year
2014, and 08 means the 8th cruise in 2014.
Former JODC ship codes were assigned as two alphanumeric characters, and the JODC now
adopts the international radio call sign for ship identification because it is possible that the old shipcodes will expire in the near future. On the other hand, the NCEI assigns three kinds of ship codes: theNODC code, which consists of two figures for the country code and two alphanumeric characters forship identification, the WOD code with three or more figures, and a call sign (seehttp://www.nodc.noaa.gov/General/NODC-Archive/platformlist.txt).

The

NODC

codes

also

synchronize with ICES ship codes, which are assigned by the ICES data center. For example, theRyofu Maru of the JMA has been assigned 49UP, 49RY and 49UX from newest to oldest. Note thatthe country code in the NODC code is an original one, different from ISO 8601:2004 described in theprevious section.
As for cruise identification, the CCHDO and CDIAC use an EXPOCODE that consists of a NODC
ship code and cruise departure date (Swift and Diggs, 2008). For example, the EXPOCODE is
automatically determined as 49UP20140923 for the above-mentioned cruise of the Ryofu Maru of the
JMA. Nevertheless the data originator’s cruise number should recorded on database as metadata
because of compatibility and continuity.

6. Data Policy
The intellectual property rights to the observed data basically belong to the organization thatprovides the facilities and equipment, and the data originator usually has a priority of data use rights inorder to research, study and write documents. Unfortunately, its term is frequently unclear in
regulation and several further parameters need a long time to fix values by calibration or quality
control, so data publishing is often behind schedule. Working Group on Scientific Data Network
Facilitation (2004) pointed out that some data originators are not so conscientious to publish and shareobserved data using the public facilities and equipment, so they often monopolize the data.
The NODC basically follows the IOC data exchange policy (IOC, 2003), while the JODC requests
that users express that they have used its materials and submit one copy of the document and productto the JODC, and no reproduction of data can be provided to a third party without permission. As
described in a previous section, the JODC submits their data to the NCEI in order to have it mergedwith that of the WOD, according to IODE recommendations of the WOD and GODAR, and the JODC
shares WOD data with the J-DOSS.

7. Data Citation
Cruise reports are published with oceanographic data, and the scientific findings are also publishedin scientific journals through the peer review process. Both are used as references in other reports andarticles; however, it is difficult to refer to oceanographic data because there is no citation information
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in the data or databases such as the WOD and the J-DOSS, so the referenced data is mentioned in
thanks at the end of an article or in the acknowledgements, which means the referenced data is notcountable in the number of citations. The IODE therefore discussed this problem in cooperation with
the SCOR, the BODC, and the MBLWHOI (Leadbetter et al., 2013).
On the other hand, the ocean carbon synthesis community has established projects, such as
SOCAT for ocean surface and GLODAPv2 for ocean interior, and results of data synthesis from bothprojects were submitted to the ESSD, a data publication journal. Furthermore, the CDIAC archives
other products from the projects, including technical documents and all cruise data, attached citations
and DOIs. An increase in the number of references for oceanographic data will be rated highly by data
originators and managers. The ESSD and DOIs are also important for digitizing historical data, andidentification and citation of massive databases. The data citation issue is also being discussed in oneof the working groups of the RDA in cooperation with researchers of other scientific fields.

8. Concluding Remarks
In this paper, we have explained that observed data and metadata are submitted to the NODC of
the IODE so that the data is available for international exchange and sharing among researchers in theocean sciences and other science fields. In addition, it is also important to recover or digitize historical
data that were recorded to analog media such as paper using recent technologies, but it is not so easy
to guarantee resources for such a project. The IODE created the GODAR project in order to search forand rescue historical data in the IOC member states, and the JODC conducted GODAR-WESTPAC,
one of the regional GODAR projects. The global and regional GODAR projects have been terminatedbut GODAR has been recommended by the IODE again and their results have been summarized in the
WOD.
Acknowledgements
We would like to thank staff of the JODC for useful comments and suggestions.
References
IOC (2003): IOC Oceanographic Data Exchange Policy, Resolution XXII-6, IOC-XXII/3 Annex II,
7ï9.
IOC (2010): Recommendation to adopt IOS 3166-1 and 3166-3 Country Codes as the Standard for
Identifying Countries in Oceanographic Data Exchange, Ocean Data Standards, Vol. 1, IOC
Manuals and Guides No. 54, Vol. 1, Paris, IOC of UNESCO, 15 pp.
IOC (2011): Recommendation to adopt ISO 8601:2004 as the Standard for the Representation of Dates
and Times in Oceanographic Data Exchange, Ocean Data Standards, Vol. 2, IOC Manual andGuides No. 54, Vol. 2, Paris, IOC of UNESCO, 17 pp.
IOC (2013): Recommendation for a Quality Flag Scheme for the Exchange of Oceanographic andMarine Meteorological Data, Ocean Data Standards, Vol. 3, IOC Manual and Guides No. 54, Vol.
3, Paris, IOC of UNESCO, 12 pp.
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Leadbetter, A., L. Raymond, C. Chandler, L. Pikula, P. Pissierssens, and E. Urban (2013): Ocean Data
Publication Cookbook. IOC Manual and Guides No. 64, Paris, IOC of UNESCO, 41 pp.
Schlitzer, R. (2015): Ocean Data View, http://odv.awi.de/
Swift, J. H. and S. C. Diggs (2008): Description of WHP-Exchange Format for CTD/Hydrographic
Data, CLIVAR and Carbon Hydrographic Data Office, UCSD Scripps Institution of Oceanography,
19 pp.
Rigaku GƝWD QHWWRZƗNX suishin ZƗNLQJX JXUǌpu [Working Group on Scientific Data Network
Facilitation] (2004): Rigaku GƝWDEƝVX kouchiku sokushin to GƝWD QHWWRZƗNX taisei no seibi ni
mukete [Heading towards Facilitation of Scientific Database Construction and Development of a
Data Network System], Subcommittee of Science Data Network Promotion, Section No. 4, 17thphase of the Science Council of Japan, 182 pp. (in Japanese) [Available on line at
http://center.stelab.nagoya-u.ac.jp/ rigakunet/rigakunet.html]
Abbreviations and Acronyms
ADU

Associate Data Unit

BODC

British Oceanographic Data Centre

CCHDO

CLIVAR and Carbon Hydrographic Data Office

CDIAC

Carbon Dioxide Information Analysis Center

CLIVAR

Climate and Ocean: Variability, Predictability, and Change

CSR

Cruise Summary Report

CSV

Comma-Separated Values

CTD

Conductivity, Temperature and Depth profiler

DOI

Digital Object Identifier

ESSD

Earth System Science Data

FETI

Format of Exchange and Translation for Integration

GLODAPv2

Global Ocean Data Analysis Project Version 2

GMT

Greenwich Mean Time

GODAR

Global Oceanographic Data Archeology and Rescue

ICES

International Council for Exploration of the Sea

ICSUInternational Council for Science

IOCIntergovernmental Oceanographic Commission of UNESCO

IODEInternational Oceanographic Data and Information Exchange of IOC of
UNESCOJAMSTEC

Japan Agency for Marine-Earth Science and Technology

JCOMM

Joint WMO-IOC Technical Commission for Oceanography and Marine
Meteorology

JMA

Japan Meteorological Agency

JODC

Japan Oceanographic Data Center

JST

Japan Standard Time

MBLWHOI

Marine Biological Laboratory, Woods Hole Oceanographic Institution

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NCEI

National Center for Environmental Information (USA)NODC

National Oceanographic Data Center

NOP

National Oceanographic Program

OBIS

Ocean Biogeographic Information System

PDF

Portable Document Format

RDA

Research Data Alliance

SCOR

Scientific Committee on Oceanic Research

SOCAT

Surface Ocean CO2 Atlas

UNESCO

United Nations Educational, Scientific and Cultural Organization

WDS

World Data System

WHP

WOCE Hydrographic Programme

WMO

World Meteorological Organization

WOCE

World Ocean Circulation Experiment

WOD

World Ocean Database

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Calculation of the Thermophysical Properties of Seawater (2010)

A manual of “Calculation of the Thermophysical Properties of Seawater (2010)” , Manuals andGuides 56, IOC, can be obtained from a GO-SHIP web site as below.
http://www.go-ship.org/Manual/TEOS-10_Manual_06Jul10.pdf

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Water sampling‫ۑ‬Toshiya NAKANO (Japan Meteorological Agency), Hajime OBATA (The University of Tokyo),
Kenichi KATAYAMA, Satoshi OZAWA and Hiroshi MATSUNAGA (Marine Works Japan Ltd.)To obtain the data of physical and biogeochemical parameters in the ocean, we often need tocollect water samples. By selecting the suitable water sampling method for the parameters to bemeasured, we will be able to get high-quality data. It is also necessary to maintain the sampling tools
at better conditions by washing them and/or replacing some parts periodically.

1. Outline for water sampling
In order to obtain high quality data, it is important to use suitable water sampling bottles for theparameters to be measured. For the hydrographic observation in the open ocean, the Nansen water
sampling bottle had been used until the CTD (Conductivity Temperature Depth profiler) system wasdeveloped in the 1970s. At present, the multi-bottle sampling system (e.g. Carousel Water Sampler by
Sea-Bird Electronics, Inc., USA and Intelligent Rosette Water Sampling System by General Oceanics, Inc.,
USA) with CTD system is available. The multi-bottle sampling system is optimized for use of 12/24/36
water sampling bottles, from 1.2 to 30 L. On the other hand, the Niskin water sampler, Van Dorn water
sampler and Kitahara’s water bottle (RIGO-B) are used in the coastal regions.

2. Seasurface water sampling (Sea-bucket method)
For surface water (well-mixed sea water from the depth of 1 to 2 m), the sea-bucket method andthe intake method are commonly used. For sea-bucket method, the bucket (about 5 L) is used tocollected the sea water from the side of the ship (Japan Meteorological Agency, 2015). For the intake
method, seasurface water is pumped up by inlet pipe in the bottom of the ship
The sea-bucket method is as follows:
1) To not lose a bucket, the end of the rope should be tied to the deck rail as a matter of precaution.
2) After filling the bucket with seawater and discarding them two or three times for rinsing, the water
should be collected from the sea surface, and the water temperature should be measured on deck.
During sampling, it is necessary to keep the bucket in water for a few minites to get filled, and thenhaul the bucket up quickely to the deck.

3) To not contaminate the water sample, water should not be collected near the drain from the engine andkichen of the ship.
4) The temperature of the seawater should be measured in a shady area. During the measurement, thewater in the bucket should be contiously strirred. The temperature should be measured quickly using
thermometer, when it attains a steady value aftrer about 1 minute.
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5㸧Water sample for measurements of salinity, dissolved oxygen etc., should be obtained after watertemperature measurement.

5) After temperature measurement and water sampling, the sea water in the bucket should be dumped
quickely, and the bucket should be washed with fresh water and turned upside down

3. CTD multi–bottle sampling system
The Niskin water sampling bottle (Niskin bottle, Figure 1) by General Oceanics or Ocean Test
Equipment is frequently used for the CTD multi–bottle sampling system. The Niskin bottle consists ofa body and end stoppers by hard vinyl chloride, spring for closing end stoppers, and rod. The volumeof Niskin bottle is available 1.2 L, 1.7 L, 2.5 L, 5L, 8 L, 10 L, 12 L, 20 L and 30 L. The structure of
Niskin sampling bottle is simple. The water inside of the bottle is easily exchanged. After colletting
the water, leakage is rarely observed. We can customize Niskin bottles for the targeted parameters bycoating the inside of the bottle, or selecting stainless spring or rubber to close the end stoppers, orchanging the materials of O-ring. Detailed maintenance procedures of Niskin bottle and multi-bottle
sampling system are described in Appendix A.1.
Moreover, we can also equip the Niskin bottle with a reversing thermometer/pressure gauge to confirm
the depth where the sampling bottle is closed.

Figure 1. Overview of water sampling bottle (Left: Niskin sampling bottle, Right: Niskin-X sampling bottle㸹
General Oceanics, Inc., USA)

4. Clean seawater sampling
Trace metals in sewater are now important topics in oceanographic researches because some ofthem are limiting factors for phytoplankton growth in Hgih Nutrient, Low Chlorophyll (HNLC) areas.
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Despite their importance, we don’t have enough data to discuss trace metal distributions and theirbiogeochemical cycles. Some essential trace metals for phytoplankton growth, like Fe and Zn, arecategolized as contamination-prone elements in the ocean science because Fe is ubiquitous in the
research ship and Zn is also frequently used in ocean observation equipments as sacrificial anode.
Once the trace metals in seawater are contaminated during seawater sampling, it is impossible to study
their distributions and biogeochemical cycles. Therefore, we need to apply the clean sampling method
for the study of trace metals in seawater.
For the last three decades, the clean seawater sampling system has been developed rapidly.
Especially through the international project, GEOTRACES, we have established the clean sampling
method for trace metals in seawater. Here, the clean sampling method for trace metals in seawater is
described breifly.
4-1. Seawater sampler

Seawater sampler is the most important equipment for clean sampling because it directly gets incontact with seawater. To prevent metal contamination to seawater samples, many original samplers
have been developed, but now commercial samplers are available for clean sampling. For example,
GO-Flo samplers (General Oceanics, Fig. 2) have often been used by US group for a long time
(Brulad et al., 1979). Recently, Niskin-X samplers (General Oceanics, Fig. 3) have been used for clean
sampling by Japanese group, too (Kim et al., 2015). For clean sampling, we have to exchange theoriginal petcocks to Teflon ones, and original O-ring to Viton ones. Also, we can prevent metal
contamination from the sampler’s wall to seawater by Teflon coating.
To collect contamination-free seawater, we have to clean the samplers before the research cruise.
After removing the organic compounds on the wall of the samplers with surfactants, we fill the insideof the samplers with 0.1M hydrochloric acid to remove the adsorbed metals. Since remaining acid in
the samplers often causes a serious contamination problem, we fill the inside of the samplers withultra-high purity water (UHPW) for one day. Otherwise, the samplers are soaked with open ocean
seawater to remove the remaining acid. After cleaning the samplers, we have to keep the samplers
clean so as not to be contaminated by air dusts.

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Figure 2. Schematic diagram of GO-Flo sampler (a. whole picture, b-1. closed, b-2. open)

Figure 3. Niskin-X sampler (a. closed, b. open)

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4-2 Sampling Procedure

When we use the clean samplers, we also have to be careful about contamination from the wire bywhich the samplers were hung. We can hang the samplers directly onto the hydrowire, but theseawater samples are often contaminated from the hydrowire itself, especially for trace metals like Fe.
Moreover, the hydrowire is usually coated with grease, which possibly causes contamination onorganic compounds in seawater. These contamination problems can be solved by using polyamiderope, like Kevler rope, or titanium wire. For a long time, the most reliable sampling method was tohang the GoFlo sampler onto Kevelar rope (Burland et al., 1979). We also have to keep the sheaves
clean where the direction of the rope is changed because grease is often used on the sheaves. By using
plastic sheaves, this problem will be avoided. To keep the sampler at the desired depth, we hang someweights at the end of the wire. The distance between the weight and sampler should be long enoughnot to cause contamination on seawater sample. Messengers, to close the sampler, should be madewith Teflon or be Teflon-coated. The Teflon-coated messenger can be commercially obtained.
Recently, it has become common to get the clean seawater samples with CTD sensors and multiple
sampling system (Measures et al., 2008; Cutter and Bruland, 2012). During international
GEOTRACES projects (http://www.geotraces.org/), it is required to perform spatially dense
observations for mapping distributions of the trace elements and their isotopes. When CTD sensors
and a multiple sampling system are used for investigations on trace elements and their isotopes inseawater, seawater samples might be contaminated from normal armoured cable. Contaminations arealso caused by grease released from the normal armoured cable. Now, polyarylate (e.g., Vecrtan)armoured cable is available and widely-used for CTD observation in the world. In Japan, titanium
armoured cable has been used for clean sampling in R.V. Hakuho-maru, which enabled us todetermine trace elements in seawater. Recently it has been difficult to get the Ti-cable. Alternatively,
Vectran armoured cable are now available in Japan. Care must be taken on the sheave not to
contaminate the cable with greese and rust. We also have to keep the frame, onto which clean
samplers are deployed, contamination-free. In the GEOTRACES project, epoxy-coated aluminium
frames have often been used (Sohrin and Bruland, 2011). However, it is known that Zn sacrificial
anodes, used on the frame, easily contaminate Zn in seawater, hence the anodes must be removed fromthe frame prior to the sampling. On the other hand, original titanium frame, for which Zn anodes are
not necessary, was built in the Netherlands (De Baar et al., 2008). For sub-sampling from the

Niskin-X sampler, the sampler was taken into a clean-air area (filled with air which was
passed through HEPA filter) and samples were collected in sample bottles with positive airpressure.
Detailed sampling methods of the international GEOTRACES project are described in “cookbook,”
published on the web site (2013 GEOTRACES Standards and Intercalibration Committee, 2014,
http://www.geotraces.org/science/intercalibration).

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5. Water smapling in the coastal region
The Van Dawn water sampler and Kitahara style (Rigaud B number) water sampler are widelyused in the coastal region, river and lake (Figure 4). Since the Van Dawn water sampler is consist of aplastic body with rubber cap, it is often used for sampling for radionuclides, phytoplankton andbacteria. On the other hand, Kitahara’s style (RIGO-B) water sampler is used for quality survey ofwater and sewerage.

Figure 4. Van Dorn Water Sampler (Left) and Kitahara’s type (RIGO-B) Water Sampler (Right)

6.

Water sampling layer and order
The standard sampling depths in m samples are: 0 (bucket), 10, 20, 30, 50, 75, 100, 125, 150, 200,

250, 300, 400, 500, 600, 700, 800, 900, 1000, 1250, and below (intervals of 250 m). However, we canchange the sampling interval for the purposes and/or region of hydrographic observation. For
basin-scale hydrographic observation, such as the GO-SHIP (Global Ship-Based Hydrographic
Investigation Program; http://www.go-ship.org) program, we can adopt a staggered scheme sampling
pattern (Swift, 2010) for getting a high resolution data set.
During the water sampling, seawaters in the sampler are easily warmed to the room temperature
and affected by surrounding air. Therefore, we should preserve the seawaters for dissolved gas (e.g.
chlorofluorocarbon, dissolved oxygen and dissolved inorganic carbon) into bottles immediately.
Samples of log sheets for information of station (date, time, position and water depth, etc.) and water
sampling (sampling layer, bottle number, sampling parameter and bottle flag etc.) are denotes in Table
1 and 2.
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Table 1 CTD operation log sheet

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Table 2 Sampling log sheet

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Ackowledgements
Figures of Niskin sampling bottle was provided by Mr. Tanaka (K-Engineering Co. Ltd.). Figuresof Van Dorn water sampler by Mr. Matumoto (RIGO Co., Ltd.).

References
2013 GEOTRACES Standards and Intercalibration Committee (2014)㸸Sampling and Sample-handling Protocols
for GEOTRACES Cruises.
http://www.geotraces.org/images/stories/documents/intercalibration/Cookbook.pdf
Bruland, K. W., R. P. Franks, G. A. Knauer, and J. H. Martin (1979): Sampling and analytical methods for thedetermina- tion of copper, cadmium, zinc, and nickel at the nanogram per liter level in sea water. Analytica et
Chimica Acta, 105, 233-245.
Cutter, G. A., and K. W. Bruland (2012): Rapid and noncontaminating sampling system for trace elements inglobal ocean surveys. Limnology and Oceanography: Methods, 10, 425–436.
De Baar, H. J. W., K. R. Timmermans, P. Laan, H. H. De Porto, S. Ober, J. J. Blom, M. C. Bakker, J. Schilling,
G. Sarthou, M. G. Smit, and M. Klunder(2008)㸸Titan: A new facility for ultraclean sampling of traceelements and isotopes in the deep oceans in the international GEOTRACES program. Marine Chemistry, 111,
4-21.
Japan Meteorological Agency (2015)㸸Guide to Weather Observations for Ships. 72pp.
Kim, T., H. Obata, T. Gamo, and J. Nishioka (2015): Sampling and onboard analytical methods for determining
subnanomolar concentrations of zinc in seawater. Limnology and Oceanography: Methods, 13, 30–39.
Measures, C. I., W. M. Landing, M. T. Brown, and C. S. Buck (2008): A commercially available rosette system
for trace metal–clean sampling. Limnology and Oceanography: Methods, 6, 384–394.
Sohrin, Y. and K. W. Bruland (2011): Global status of trace elements in the ocean. Trends in Analytical
Chemistry, 30, 1291 -1307.
Swift, J. H. (2010) 㸸Reference-quality water sample data: Notes on acquisition, record keeping, and evaluation.
IOCCP Report No.14, ICPO Pub. 134, 2010 ver.1

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Appendix
This section describes the maintenance and management of CTD – multi-layer water samplingsystem, comprised of water sampling bottles (Niskin bottles) and multi-bottle sampling arrays(Sea-Bird Electronics carousel), used widely in many institutes today.

A.1 Managing Water Sampling Bottle (Washing and Maintenance)
Niskin bottles must be washed before sampling. After sampling, all Niskin bottles must be washedand stored or prepared for next sampling.
A.1-1 How to Wash Niskin Bottles

ձ Preparation
࣭Neutral detergent (products not subject to PRTR (Pollutant Release and Transfer Register)Law, enacted on July 13, 1999, must be used, e.g. S-CLEAN WO-23 produced by Sasaki
Chemical Co., Ltd)
࣭Plastic beaker࣭Sponge࣭Bucketղ If you have extra time1㸧Fill Niskin bottle with 1% solution of S-CLEAN WO-23, and leave it for more than 12hours.
2㸧Drain the solution. While draining, drain from petcock, to wash petcock as well.
3㸧Using the sponge and the drained solution used to clean inside the Niskin bottles, clean theoutside of Niskin bottle. Rinse both the inside and outside of the Niskin bottle with fresh
water, making sure bubbles are washed off. While draining, drain from petcock, to rinse
petcock as well. (Note: Do not apply sponge inside Niskin bottle.)
ճ If your time is limited
1㸧Make 1% solution of S-CLEAN WO-23.
2㸧Using the sponge, clean the outside of Niskin bottle. (Note: Do not apply sponge inside
Niskin bottle.)
3㸧Fill Niskin bottle with 1 litter of 1% solution of S-CLEAN WO-23. Shake the bottle
thoroughly more than 10 times, to wash every part inside the bottle. Drain from petcock, towash petcock as well.
4㸧Fill Niskin bottle with fresh water, shake the bottle and rinse until bubbles are completely
washed off inside the Niskin bottle. Drain from petcock, to rinse petcock as well.
մ Storing Niskin Bottle
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If Niskin bottle is not used in next cruise, or if storing Niskin bottle for an extended period, allow
the inside of the Niskin bottle to dry, and cover with tarpaulin to avoid dust.
A.1-2 Preparing Niskin Bottle for Sampling
A.1-2-1

Adjusting and checking tension to ensure sealing

To close the upper and lower lids, Niskin bottles have latex tube or spring (closure spring) inside
the bottle. Use spring scale to adjust the tension of 12-liter closure spring Niskin bottles to be around
12 kg (s0.5 kg). On the other hand, X-type Niskin bottles have external layard and closure spring.
For adjusting tension of X-type Niskin bottle tension, adjust the length of the lanyard. Use spring scale
to check the tension of 12-liter X-type Niskin bottle tension to be around 12 kg (s0.5 kg).
A.1.2-2

Cheking O-Ring

Check the O-rings at top and bottom of the Niskin bottle, and the O-rings at top and bottom valves(hereafter top valve is referred to as “air vent”, and bottom valve is referred to as “petcock”), for any
apparent damage such as scratch and crack. If any abnormality is found, replace the part.

A.1-2-3

Checking for Leaks

1 Perform leak check while preparing for sampling, can improve the quality of samples. Even
‫ۑ‬
E

A

during the sampling, always perform leak check, and record the results (Swift, 2010).
Make sure petcock and air vent are closed, and fill the bottle fully. First, check if there is not any
leakeage.
2 Push in the petcock, and:
‫ۑ‬
E

A

A

1㸧 If there is leakeage from the petcock, check the tension of the closure spring. If the tension
is normal, replace the O-ring at air vent, and replace the O-ring at the top lid. If it continues
to leak after replacing the O-rings, check the body of the bottle for sound of air leakeage,
especially around the mounting blocks. If you hear the sound of air leakeage, replace the
Niskin bottle.
2㸧If there is a leak from outside the petcock, replace the O-ring in the center of the petcock.
3㸧If taking actions in above steps 1) and 2) does not improve the situation, replace the petcock.
And, check and see where the petcock is attached to the body of the bottle (hereafterreferred to as petcock bushing), for any scratch or crack. If anything is not normal, replaceor repair the bottle.
ճ Pull the petcock and open the air vent.
1㸧If there is a leak from the petcock, replace two O-rings inside the petcock.
2㸧If there is a leak from outside the petcock, check and see inside the petcock bushing for any
scratch. If there is no scratch, replace both of the two O-rings.
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3㸧If there is a leak from lower lid, first check the tension of the closure spring. If there is no
problem with the tension, replace the O-ring of the lower lid.
If above leak checks have been done, but leaking persists, and the cause and location of the leak(entry of air) cannot be identified, stop using the Niskin bottle, and use another Niskin buttle.

A.1-2-4

Attach upper and lower lanyard

Specifications of lanyard to use, will vary depending on the type of Niskin bottle and type ofCarousel. Please be sure to use the appropriate lanyard. Lanyard used with Niskin bottles is often
made of nylon, and #150 (2mm) is recommended for use with Carousel.

A.1-2-5

Adjust upper and lower lanyard

If lanyard attached to Niskin bottle is too short, Niskin bottle may not close even after sending thefire command. Therefore, length of lanyard must be adjusted before sampling.
ձ Prepare Niskin bottle for sampling (hook outside, as shown in Photo A.1-2-1)).
ղ In the state described in previous step ձ, press and hold the lower lid to make sure the lid
does not close (as shown in Photo A.1-2-1).
ճ While keeping both the upper and lower lid closed, hook the lower lid lanyard, and check thetension of lanyard (as shown in Photo A.1-2-2).

Photo A.1-2-1 Checking tension of lower lid lanyard.

Photo A.1-2-2. Checking tension of upper lid lanyard.

References
Swift, J.H. (2010)㸸Reference-quality water sample data: Notes on acquisition, record keeping, and evaluation.
IOCCP Report No.14, ICPO Pub. 134, 2010 ver.1

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A.2 Checking and Maintaining Carousel
Carousel is composed of trigger part and housing part. This section describes how to maintain eachpart.
ձPreparationx

Hex Wrench (Inches)xMonkey Wrench (Small)x

Flat head screwdriverx

Phillips screwdriverx

Precision screwdriverx

3 Jack-up Screwsx

Malletx

Ethanol (if necessary)x

Carousel pedestal (Nice to have dedicated pedestal having height of 40 cm or more, to prevent
carousel from falling out)x

Silicon greasex

Silicon sealant (if necessary)xWiper (JK Wiper, Kimwipes, etc)x

Molybdenum greasex

Threadlocker (Loctite 222, etc)

A.2-1 Disassemble and Reassemble Carousel

Be aware that disassemblying and reassemblying 36-bottle carousel will be different from that of
12-bottle carousel or 24-bottle carousel. Depending on the material used in the housing, its parts may
be using different materials and screws. Therefore do not mix the parts used with 6,800 m carousel
with the parts used with 10,500 m carousels. Furthermore, triggers used uniquely with 36-bottle
carousels will have imprints of “36” on its sides, and are different from those used with 12-bottle
carousels and 24-bottle carousels.

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A.2-2 Detach Latch Assembly

Hereafter, the location where the triggers are attached, is collectively referred to as latch assembly.
ձ 12-bottle, 24-bottle
1㸧Remove titanium screws located in the center of the top.
㸦Use 1/8 inch hex wrench for 6,800 m type, and use
monkey wrench for 10,500 m type.
㸺References㸼࣭6,800 m type: Stainless steel hex socket head cap screw
࣭10,500 m type: Titanium hex bolt

Photo A.2-2-1 Latch Assembly2㸧Detach latch assembly from housing.

Photo A.2-2-2 Removing from housing

3㸧Use driver to remove 6 titanium screws on retainer disc.
Depending on housing type, screw head may be Phillips or
Flat.
࣭Phillips: Stainless࣭Flat head: Titanium

Photo A.2-2-3 Retainer Disc part

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4㸧When removing retainer disc, mark the trigger #1.
5㸧Remove retainer disc at top center of carousel. When it isstuck, hit lightly from bottom (back) to remove it with ease.

Photo A.2-2-4. Removing Retainer Disc

6 㸧 Remove the trigger attached to #1, mark thecorresponding part with #1. Remove the corresponding
trigger.

Photo A-2-2-5 Removing trigger frommount disc.

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ղ 36-Bottle

1㸧Use 5/32 inch hex wrench to remove 3 white color
plastic screws (some carousels may not have thosescrews).
2㸧Use Phillips driver to remove 6 titanium screws on
retainer disc.
Photo A.2-2-6 Top of 36-bottle carousel (topcenter part is retainer disc)3㸧In the holes where screws were removed in thestep 1㸧, insert 3 jack-up screws, use 1/8 inch hex
wrench to tighten the 3 screws equally, and lift up theretainer disc. If jack-up screws are not tighten
equally, disc may distort.
Photo A.2-2-7 Lifting up disc by inserting
jack-up screws

4㸧When disc lifts up, remove it straight upward.
5㸧Remove triggers from trigger mount disc.

Photo A.2-2-8 After removing retainer disc(trigger mount disc)

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A.2-3 Reassemble Latch Assemblyձ 12-Bottle 24-Bottle
1㸧Put the triggers back onto trigger mount disc.
2㸧When putting the triggers back to trigger mount disc, look for the marking that says
“Trigger #1” and use this location as base location. Make sure trigger mount disc holds
triggers firmly.
3㸧Place the retainer disc at position of trigger #1.
4㸧Apply small amount of molybdenum grease on the 6 titanium screws, use driver to tighten
the screws equally, and complete reassemblying the latch assembly part.
5㸧Place the latch assembly on the housing.
6㸧Use the 3 screws to secure the latch assembly on the housing. Apply small amount ofmolybdenum grease on the screws. Tighten all the screws equally, to avoid one part being
tighter than the other part. Use 1/8 inch hex wrench for 6,800 m type, and use smallmonkey wrench for 10,500 m type.
7㸧Make sure triggers operate smoothly.
ղ 36-Bottle
1㸧Attach the triggers to trigger mount disc on the housing part.
2㸧Attach retainer disc at top center part of carousel. Adjust the locations of the triggers for theretainer disc to fit smoothly. If the disc does not fit, use a mallet to hit lightly on it to allow
it to fit.
3㸧Use Phillips driver and hex wrench to secure retainer disc with 6 titanium screws. Apply
molybdenum grease on the screws. Tighten all the screws equally, to avoid one part being
tighter than the other part.
4㸧Make sure triggers operate smoothly again.

A.2-4

Maintain trigger part

This part describes maintenance of triggers. Keep oil and grease away from trigger function part.
The gray paint on the triggers reduce resistance under water, and this paint is easily removed byscratches from shock or friction. For more details on trigger, refer to the drawings and references
offered by the manufacturer, which describes how to assemble triggers. Top of screws used in triggers
are easily damaged. Please use right size of tools.
ձWash trigger part
Remove carousel from CTD frame, and leave it in fresh water for a day and a night, to remove salt
deposit. If time allows, remove the triggers, and put the carousel housing and triggers separately infresh water for a day and a night. After removing salt deposit, make sure housing part and trigger partare normal, and reassemble the triggers, reversing the steps to separate them.
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If trigger parts have visible salt deposit, wash them well in lukewarm water of temperature 40°C
mixed with neutral detergent. Move the movable parts while washing. Rinse well to wash off bubbles,and soak them in fresh water.
ղVisual check trigger part
If conditions like below are visually appearant in the triggers, consider to replace triggers or partsof triggers (Photo A.2-4-1).
࣭Paint on the trigger has been removed
࣭Trigger hook is worn out
࣭Trigger side plate is visually and appearantly ditorted
࣭Severe corrosion on back of the actuator disc
࣭Wear and bend in shaft such as trigger pivot shaft
࣭Severe wear in trigger lever

Actuator disc

Trigger hook

Trigger lever
Side plate
Trigger pivot shaft

Photo. A.2-4-1 Trigger parts
Hold the trigger as shown in picture below, trigger hook pointing straight down (Photo A.2-4-2),
and push the white lever (encircled in red) with a finger, in the direction indicated by the arrow in the
picture (handle the lever with care, pushing too strong may damage the lever). While doing thismotion, if trigger hook freely drops down, this is normal. If the hook does not drop down, or there issome interference preventing the hook to drop down, loosen 2 screws holding the actuator disc, andadjust them so that the hook is released smoothly. If screws seem already loosen, apply threadlocker
on the screws and tighten the screws. However, tightening the screws too much, may damage thetrigger lever.

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 
Photo A.2-4-2 Check trigger function

A.2-5 Check and maintain carousel housing part

This section describes how to check and maintain the housing part.
ձ

External visual check on housing part

Remove latch assembly from the housing.
Look closely on electromagnet part, and check if
there is no tear or wear on the rubber that coats theelectromagnets. If the part is rusty, this check must
be done extra carefully.
Electromagnet

Photo A.2-5 Electromagnet partIf there is major damage on the rubbber, spread silicon grease thinly on the damaged part, andleave until it is dry and hardened. And after reassembly, make sure triggers are released normally. If
damage is too severe to use, consider to repair by repair service provider. If rust and salt crystals areseen, remove them to the possible extent.

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Water temperature‫ۑ‬Toshiya NAKANO (Japan Meteorological Agency)

Water temperature (temperature) is the most fundamental physical properties of sea water withpressure and salinity in the International Thermodynamic Equation Of Seawater–2010 (TEOS-10).
The vertical and horizontal distributions of temperature are associated with the thermal and dynamic
structure in the ocean. Temperature is a key variable that supports oceanic condition, ocean andweather prediction, and air-sea interaction leading to understanding and forecasting short- andlong-term climate variability.

1. Definition and Unit
In 1990 the International Practical Temperature Scale 1968 (IPTS-68) was replaced by theInternational Temperature Scale of 1990 (ITS-90) defined by 17 fixed temperature points. The triple
point of water (273.16K or Û& remains unchanged on ITS-90, however, the definition of boilingpoint of water at the atmospheric pressure falls to 99.974Û& (Rusby, 1991). Since many algorithms forcalculating physical properties of seawater had been based largely on IPTS-68, it was necessary todiscriminate between IPTS-68 and ITS-90. In the field of oceanography it is common to distinguishuseing subscripts as t90 with the Celsius scale (ÛC). The relation between ITS-90 (t90) and IPTS-68 (t68)can be adequately represented by the expression
t90 = 0.99976㺃t68

㸦1㸧

This linear transfomation is accurate within 0.5×10í3 K throughout the oceanographic temperature
range –2Û& to 40ÛC (Saunders, 1990). Temperure reported in the literature is used ITS-90 and belabelled t90. In order to use the International Equation of State of Seawater 1980 (EOS-80) with t90 data,
t68 may be calculated using
t68 = 1.00024㺃t90

㸦2㸧

2. Calibration of thermometers
To ensure traceability to the national standards, all thermometers need to be calibrated by astandard device such as a Standard Platinum Resistance Thermometer (SPRT). The standard device
also needs to be calibrated by a higher standard device or by ITS-90 fixed point cells. These higher
standard device or fixed point cells need to be traceable to the national measurement standards
maintained by the National Metrology Institute (e.g. National Metrology Institute of Japan [NMIJ] andNational Institute of Standards and Technology [NIST]). The oceanographic temperature range isrealized by use of a SPRT calibrated at the ITS-90 defining points of the water triple point, 0.01Û& andthe gallium melting point, 29.7646Û&. Calibrations of thermometers are made regularly with the
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standard thermometer fully submerged in a water bath. The temperature correction that must be
applied to the thermometer is estimated for agreement with the reading of the standard thermometer.
References
Rusby, R. L. (1991): The conversion of thermal reference values to the ITS-90. J. Chem.
Thermodynamics, 23, 1153-1161.
Saunders, P. (1990): The International Temperature Scale of 1990, ITS-90. WOCE Newsletter 10, IOS,
Wormley, UK.
UNESCO (1981): The Practical Salinity scale 1978 and the International Equation of State of
Seawater 1980. UNESCO technical papers in marine science 36, 25pp.

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Salinity‫ۑ‬Takeshi Kawano (Japan Agency for Marine-earth Science and Technology)

A manual of “Method for Salinity (Conductivity Ratio) Measurement” can be obtained from a GOSHIP web site as below.
http://www.go-ship.org/Manual/Kawano_Salinity.pdf

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Density of Seawater‫ۑ‬Hiroshi UCHIDA (Research and Development Center for Global Change / Japan Agency for Marine-Earth
Science and Technology)

The density of seawater is defined as its weight per unit volume; in accord with the International
System of Units (SI), it is expressed in units of kilograms per cubic meter (kg/m3). The density ofseawater may be estimated as a function of pressure, temperature, and Absolute Salinity by using theInternational Thermodynamic Equation of Seawater – 2010 (TEOS-10) or by direct measurement usinga densitometer. Seawater density data used in the TEOS-10 standards were obtained from density
measurements (Millero, 2010).
The density of seawater can be measured with a hydrostatic weighing apparatus or a vibrating-tube
densitometer. The former measures the buoyancy of a sinker suspended in a seawater sample. The
volume and mass of the sinker must be calibrated in advance. The latter measures the natural period ofa vibrating glass tube filled with a seawater sample. The natural period is proportional to the density ofthe sample. A hydrostatic weighing apparatus can directly measure seawater density traceable to the SI
without a reference solution. However, the measuring time for a sample is quite long (longer than several
hours), and a hydrostatic weighing apparatus cannot be used on a moving ship. Use of a single-crystal
silicon sinker has made it possible to reduce the measurement uncertainty to about 0.001 kg/m3 withtraceability to national density standards based on silicon spheres. However, the tendency of a siliconsphere to dissolve in seawater is a problem that needs to be solved. In contrast, for a vibrating tube
densitometer, which can be used on a moving ship, the measuring time for a sample is short (several
minutes). Although a reference solution is required for calibration, the resolution of the densitometer ishigh (0.001 kg/m3). Because the uncertainties of the commercially available, SI-traceable density
reference solutions are large (0.01 kg/m3 for pure water), a substitution method is normally used forseawater density measurements. In the substitution method, the density difference between a seawater
sample and pure water is measured, and the density of pure water, calculated from the TEOS-10
standards, is added to the difference.
An international guideline for seawater density measurements based on vibrating tube densitometers
is now in preparation [Wolf, H., S. Weinreben, H. Uchida and R. Pawlowicz: Best practice guide for themeasurement of seawater density. The Joint Committee on the Properties of Seawater(IAPSO/SCOR/IAPWS)]. However, seawater densities measured by the substitution method relative topure water tend to be lower (by as much as 0.01 kg/m3) than densities calculated from TEOS-10
standards (e.g., Uchida et al., 2011). Although the systematic differences are hypothesized to be theresult of systematic errors in the TEOS-10 standards or nonlinearities of vibrating-tube densitometers,a consensus has not yet been reached on the cause of the systematic differences. To solve this problem,
a precise determination of the density determined by hydrostatic weighing is planned for IAPSO
Standard Seawater, the composition of which is considered to be close to the Reference Composition
defined in the TEOS-10 standards.

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References
IOC, SCOR, and IAPSO (2010): The international thermodynamic equation of seawater – 2010:
Calculation and use of thermodynamic properties. Intergovernmental Oceanographic Commision,
Manuals and Guides No. 56, UNESCO, 196 pp.
Millero, F. J. (2010): History of the equation of state of seawater. Oceanography, 23, 18–33,
doi:10.5670/oceanog.2010.21.
Uchida, H., T. Kawano, M. Aoyama and A. Murata (2011): Absolute salinity measurements of standard
seawaters for conductivity and nutrients. La mer, 49, 119–126.

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Transparency‫ۑ‬Toshiya NAKANO (Japan Meteorological Agency)

Transparency is one of the observed elements for an index of clarity or turbidity of the sea water.
Transparency is measured with a Secchi disk, which is the simplest and the most effective tools for
estimating marine pollution and temporal changes in water quality.

1. Secchi disk
A Secchi disk is a circular white plate, 30 cm diameter with a graduated line for lowering into thesea water, attached an about 5 kg weight to hold the line vertical (photo 1).

2. Measuring transparency using the secchi disk
The depth where the Secchi disk can no longer be seen through the sea water is the Secchi disk
depth. To obtain the Secchi disk depth, the disk is lowered into the water on the shady side of the shipin the daytime, while observing the depth at which it disappears. The disk is then slowly raised, whileobserving the depth which it reappears. The measurement of the Secchi disk depth is obtained as theaverage of the two observations.

Photo1 Transparency observation㸦left㸧ࠊSecchi disk㸦upper right and lower right㸧

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Dissolved Oxygen○Yuichiro KUMAMOTO (Japan Agency for Marine-Earth Science and Technology),
Daisuke SASANO (Japan Meteorological Agency), Hironori SATO (Marine Works Japan Ltd.),
Keitaro MATSUMOTO (Marine Works Japan Ltd.)

1. Introduction
In this chapter, we describe the method for the measurement of oxygen (oxygen molecule, O2)dissolved in seawater. Surface seawater is saturated with oxygen in the air due to gas exchange
between the atmosphere and ocean. The photosynthesis by phytoplankton can supersaturate
oxygen concentration in the euphotic zone in surface layers. On the other hand, when seawater
leaves the surface layer and sinks into the aphotic zone, the dissolved oxygen concentration
decreases due to the decomposition of organic matter. Therefore, the dissolved oxygen
concentration in seawater is one of the most essential variables in oceanographic studies on theatmospheric-ocean gas exchange, seawater mixing, and biogeochemistry.
The analysis of dissolved oxygen in seawater has a long history; volumetric analysis, gas
analysis, colorimetric method, etc. have been reported (Kitano, 1964). One of the most traditional
methods among them is iodometric titration, which is one of the volumetric analyses. Thistitration method is called the Winkler method named after the first reporter (Winkler, 1888). Aftermodifications by Carpenter (1965a), this simple and sensitive analysis without expensive
instruments became a standard analytical method for dissolved oxygen concentration in seawater(Strickland and Parsons, 1972; Grasshoff, 1976; Culberson et al., 1991; Joint Global Ocean Flux
Study, 1994; Dickson, 1996; Hansen, 1999; Langdon, 2010). In addition, colorimetric methods
utilizing the measurement principle of the Winkler method have been also reported (Broenkow
and Cline, 1969; Pai et al., 1993; Labasque et al., 2004). In Japan, Japan Meteorological Agency(JMA) particularly described the modified Winkler method (hereinafter simply referred to as the
Winkler method) in the Manual on Oceanographic Observation (JMA, 1999), which has been
widely used by the Japanese oceanographic researchers/engineers. The Winkler method uses the
starch-iodine reaction (bluish purple) in the determination of the titration endpoint to heighten theanalytical sensitivity. In recent years, a photometric automatic titration without starch, whichmeasures the absorbance at the yellow color range (around 350 nm) due to liberated iodine,
becomes common because affordable automatic titrators have been easily available (Miyao et al.,2013).
Since the 2000s, we have measured dissolved oxygen concentration in seawater collected in
the open ocean using the Winkler method with a photometric automatic titrator and acquired about
0.1 μmol kg–1 of the analytical precision of repeat measurements (repeatability). As a result,uncertainty arisen from interfering substances (< 1 μmol kg–1) of the Winkler method is
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recognized, which has been ignored in the past. The Winkler method does not determine dissolved
oxygen directly. Instead, it measures dissolved oxygen indirectly by reducing titration of freeiodine (I2), which is equivalent to dissolved oxygen, to iodide ion with sodium thiosulfate.
Therefore, substances contributing to this reduction reaction in the titration condition, namely theinterfering substances are measured as "dissolved oxygen" in seawater. The dissolved oxygen andinterfering substances contained in added reagents are corrected using predetermined values. On
the other hand, the interfering substances contained in seawater itself should be corrected strictly
on each sample measurement of the Winkler method. Otherwise, dissolved oxygen concentration
measured by the Winkler method would be a total concentration of dissolved oxygen andinterfering substances. In the following sections, however, the uncorrected concentration is simply
referred to as "dissolved oxygen concentration" in order to avoid complication. The interfering
substances of the Winkler method are discussed in section 10.
In this chapter, we describe the Winkler method with the photometric automatic titrator. In
addition, the interfering substances and the uncertainty of this method are discussed. We hope that
this chapter will be helpful for marine researchers and engineers who need the high analyticalprecision of dissolved oxygen concentration in seawater samples. For the method of theconventional manual titration with starch, please refer to the Manual on Oceanographic
Observation (JMA, 1999). This chapter consists of ten sections. This introduction (1) is followedby nine sections; units (2), principle of measurement (3), reagent preparation (4), apparatus (5),sampling (6), analysis (7), calculation of concentration (8), uncertainty (9), and traceability andinterfering substances (10). One can overview all the procedures of the measurement in order of
the actual works in the sections from 4 to 9. Section 10 would help readers understand more about
the measurement of dissolved oxygen concentration using the Winkler method. Although methods
for calculation of pure water and seawater density, and calibration of volumetric apparatus(sample flasks, burettes, and pipettes) were described in the Japanese version in this chapter(Kumamoto et al., 2015), those are omitted in this English version. Please refer to other manuals(e.g. Dickson et al., 2007) for these methods.
2. Units
Dissolved oxygen concentration has been expressed as its volume at the standard condition(0 °C, 1 atm = 101325 Pa) [mL·L–1] or mass [mg·L–1] in 1 liter of seawater. However, it isrecommended to use the molar concentration (molarity), the amount of substance per liter[μmol·L–1], partly because of change of the atmospheric pressure in the standard condition in1997 (International Union of Pure and Applied Chemistry, 1997). Recent manuals use the molal
concentration (molality) [μmol·kg–1] that is not affected by the change in sample temperature. In
this chapter, we use the molal concentration [μmol·kg–1] that is converted from the molar
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concentration [μmol·L–1] using seawater density. Conversion equations for [μmol·L–1] from[mL·L–1] or [mg·L–1] are as follows.

[μmol ∙ L−1 ] = [mL ∙ L−1 ] ∙

1000
1000
= [mg ∙ L−1 ] ∙22.392(15.9994 × 2)

(1)

where 22.392 is the volume of 1 mol O2 in the standard condition (0°C, 101325 Pa) [L·mol–1].
15.9994 is the atomic weight of 1 mol O [g·mol–1].
3. Principle of measurement
Manganese chloride solution is added to a seawater sample, which is immediately followed by
the addition of potassium iodide/sodium hydroxide solution. The white precipitate of manganesehydroxide in colloidal state is formed in the strong alkaline condition.
Mn2+ + 2OH − → Mn(OH)2 ↓(2)

Some of the precipitate is oxidized with dissolved oxygen and turns brown, which is called"oxygen fixation".
2Mn(OH)2 + O2 → 2MnO(OH)2 ↓(3)

4Mn(OH)2 + O2 + 2H2 O → 4Mn(OH)3 ↓(4)

In the acidic condition, the precipitate dissolves, manganese is reduced, and iodine is liberated.
2MnO(OH)2 + 4I − + 8H + → 2Mn2+ + 2I2 + 6H2 O−

4Mn(OH)3 + 4I + 12H

+

→ 4Mn

2+

+ 2I2 + 12H2 O

(5)
(6)

In the two reactions, two moles of I2 are formed for each mole of O2. The liberated iodine reacts
with excess iodide ion and changes into triiodide ion. The amount of I3– in the solution isdetermined by titration with standardized sodium thiosulfate solution.
I2 + I − → I3 −(7)

I3 – + 2S2 O32− → 3I − + S4 O62−

(8)

Two moles of thiosulfate ion are required to titrate each mole of triiodide ion. Therefore, the final
stoichiometry of one mole of O2 is four moles of thiosulfate ion. The amount of dissolved oxygen
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can be obtained from this stoichiometry.
4. Reagent preparation
All the reagents should be higher than the special grade. Record their lot number, arrival date,and use start date. With preparing the reagent solutions, record the working date, names ofworkers, apparatus used, and the lot number and usage amount of the reagents. These records will
help you find reasons when questions arise in the measurement results. The preparation should be
carried out in a fume hood in a laboratory by more than one person. The workers are recommended
to wear gloves and safety glasses to insure themselves against risk from deleterious and dangerous
reagents, including strong acids and alkalis.
4-1. Manganese chloride solution (3 M): Pickling reagent I
Approximately 600 g of manganese chloride tetrahydrate (molecular weight 197.90) was
slowly added into about 600 mL of deionized water (DIW) in a beaker and stir with a magnetic
stirring bar until all the crystals have dissolved. Allow the solution to reach room temperature
because it becomes cool due to the endothermic reaction. Then DIW is added to make the final
volume of 1 L. The concentration is approximately 3 M (mol·L–1). If you find any particles in thesolution, filter the solution through with a glass fiber filter. Store the solution in a light-shieldable
bottle.
4-2. Sodium iodide (4 M) · Sodium hydroxide (8 M) mixed solution: Pickling reagent II
Approximate 320 g of sodium hydroxide (molecular weight 39.997) is dissolved in about 600
mL of DIW in a beaker. The solution becomes hot due to the exothermal reaction. Allow it to coolin a water tub. About 600 g of sodium iodide (molecular weight 149.89) is dissolved and allowed
it to reach room temperature again. Then, DIW is added to make the total volume of 1 L. If you
find any particles in the solution, which could contribute to the reagent blank (7-3), filter thesolution through with a glass fiber filter. Store the solution in a light-shieldable plastic bottle.
Sodium iodide is easy to be oxidized by exposure to the air or daylight and liberates iodine. The
original color of sodium iodide is white, and a yellowish reagent should not be used.
4-3. Sulfuric acid solution (5 M)
Approximate 600 mL of DIW is placed in a beaker in a cooling water tub and slowly poured
about 280 mL of concentrated sulfuric acid (molecular weight 98.079, density 1.84 g·mL–1) little
by little with gentle stirring. Be careful about a great deal of heat given off as the acid and water
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mix. Never add DIW into concentrated sulfuric acid conversely, or the DIW may boil explosively(bump). Allow the solution to cool to ambient temperature and then make up the final volume to
1 L by adding DIW.
4-4. Sodium thiosulfate solution (0.025 M)
6.25 g of sodium thiosulfate pentahydrate (molecular weight 248.19) is dissolved in 1 L of DIW
to obtain a solution of approximate 0.025 M. The concentration may decrease with time because
sodium thiosulfate is decomposed by the reaction with oxygen/carbon dioxide and activity ofbacteria in the solution. To prevent the decomposition, a preservative may be added to the solution,for example, sodium carbonate (Strickland and Parsons, 1972), sodium borate (Joint Global
Ocean Flux Study, 1994), and 3-methyl-1-butanol (Fujifilm Wako Pure Chemical Corporation,2018). Tanaka et al. (2007) reported that the concentration does not change when boiling DIW isused. Even without a preservative, it has been found empirically that the solution is more stable
and consistent if it is left a few days after the preparation (Langdon, 2010). This could be
explained by the slowdown of the decomposition rate by the aging. This titrant solution has been
often called "hypo" wrongly, which is derived from a confusion between sodium thiosulfate andsodium hyposulfite.
The concentration of the sodium thiosulfate solution should be determined by the volume of
the burette for the titration (5-2-1). To titrate 100 mL of seawater whose oxygen concentration is
as high as 400 μmol·L–1 (40 μmol), 6.4 mL of 0.025 M sodium thiosulfate solution is required. If
the volume size of the titration burette is 5 mL, the concentration of the titrant solution must be
increased.
4-5. Potassium iodate standard solution (1/600 M)
The standard solution in the Winkler method is a solution of potassium iodate (molecularweight 214.001, density 3.89 g·mL–1). Iodate ion oxidizes iodide ion to iodine in the acidic
condition.
−+
IO−→ 3H2 O + 3I2
3 + 5I + 6H

(9)The liberated iodine reacts with excess iodide ion and changes into triiodide ion that is reducedwith sodium thiosulfate (equations 7 and 8). In these reactions, 1 mole of iodate ion corresponds
to 6 moles of thiosulfate ion. The concentration of sodium thiosulfate solution is determined fromthe volume of the titrant solution required for the titration of triiodide ion (the endpoint of thetitration) and the concentration of the potassium iodate solution, which is called the
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standardization of the sodium thiosulfate solution (7-2). Although the special grade of potassium
iodate powder is affordable, it is recommended to use the certified standard substance. In Japan,
National Metrology Institute of Japan (NMIJ) supplies "NMIJ CRM 3006-a" (NMIJ, 2015).
Procedures for preparing the standard solution of potassium iodate by the gravimetric method are
as follows. It should be noted that the uncertainty of the oxygen measurement by the Winkler
method is dependent on the care you take with the preparation of this standard solution. The
standard solution of potassium iodate is commercially available. For example, Fujifilm Wako
Pure Chemical Corporation provides Cooperative Study of Kuroshio Standard Solution (0.0100
N = 1/600 M, sales code 034-10251). However, this standard solution cannot be used for theoxygen measurement with less than 1% of the analytical uncertainty.
4-5-1. Preparation of electronic balances
Prepare a precision electronic balance with 200 g of weighing capacity and 0.01 mg ofreadability for weighing potassium iodate. To eliminate disturbance due to static electricity, aprecision balance with an electrostatic eliminator and a shield made of conductive acrylic fiber isrecommended. Also, prepare another balance with about 10 kg of weighing capacity and 10 mgof readability for weighing of the standard solution. The electronic balances must be calibrated
by standard weights before use.
4-5-2. Drying potassium iodate
About 0.5 g of high-purity potassium iodate is pulverized in a mortar, taken in a beaker, driedat 130 ºC for about 2 hours, and allowed to cool in a desiccator with silica gels.
4-5-3. Weighing potassium iodate
Weigh out about 0.36 g of potassium iodate in a weighing bottle with a lid and measure theweight with the precision balance.
4-5-4. Transfer of potassium iodate
Place a 1-L volumetric flask on the balance for the solution and measure the tare weight. Openthe lid of the weighing bottle and transfer potassium iodate to the flask using a powder funnel.
Potassium iodate powders on the funnel are washed out into the flask using DIW. At this time, do
not moisten the weighing bottle with DIW. Measure the weight of the empty weighing bottle withthe lid using the precision balance. Calculate the weight of potassium iodate (wKIO3 [g]) transferredfrom the weighing bottle to the flask from a difference between the weights of the weighing bottle
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before and after the transfer.
4-5-5. DIW addition and weight measurement
Add DIW to the volumetric flask and dissolve potassium iodate. Then dilute the solution to a
final volume of 1 L in the volumetric flask and record the sum of weights of the potassium iodate
and DIW (wdw + wKIO3 [kg]). At this time, you do not have to make up to exactly 1 L because theconcentration is calculated not by the volume but the weight.
4-5-6. Stirring
Cap the volumetric flask with a stopper and mix the solution in the flask by overturning. Thenstir the solution using a magnetic stirring bar for 1 hour or more to completely dissolve thepotassium iodate.
4-5-7. Storage
Aliquot the solution into brown glass bottles (250 or 500 mL volume). An aliquot of the solution
should be used up once for each of the standardizations. Do not reuse the opened solution after
the first use. The potassium iodate solution is chemically stable. However, evaporation from thenarrow gap between the glass bottle and the screw cap results in the rise of the concentration
during a long-time storage. This can be prevented by sealing the glass bottle with an airtight vinyl
bag using a vacuum sealer machine for kitchen packaging, which allows the standard solution to
be used for a few years.
5. Apparatus
5-1. Sampling apparatus
5-1-1. Sample flasks (Oxygen bottles)
Use an "iodine titration" glass flask of 100 mL nominal volume with a flared neck and groundglass stopper, which is called "oxygen bottle". The oxygen bottle is a container for collecting
seawater and serves as a flask for titration. The flared neck is used to prevent contamination fromatmospheric oxygen during the water sampling and storage. The ground glass stopper should belong enough to make a headspace in the oxygen bottle for the titrant solution added. The volumeof the bottle with the stopper must be calibrated by a weighing with the buoyancy correction(Dickson et al., 2007). An oxygen bottle whose volume has already been measured iscommercially available. However, the volume calibration is recommended for the confirmation.
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The oxygen bottle and stopper should be handled with care because scratches or chips on the innerwall of the bottle or stopper may change the volume calibrated, which results in the error in themeasurement. Each bottle/stopper pair must be numbered so as not to confuse it with other pairs.
It is sometimes difficult to remove the stopper from the dry bottle because of the ground glass
joint. To avoid this, the bottle and stopper should be stored separately or with a slip of paper
between the bottle and stopper. In the former case, be careful not to pollute the inside of the bottle.
After use, the bottle and stopper should be washed with DIW and dried at room temperature (neveruse a heating oven). When the ground glass joints become brown, soak the bottles and stoppers
in hydroxylammonium chloride solution (about 200 g·L–1) for about ten minutes and wash out.
5-1-2. Water sampling tubes
A transparent plastic tube, such as a silicone tube, is recommended so that air bubbles in it canbe easily found. A new tube should be soaked in DIW before use, which may prevent air
entrapment in the tube (Dickson, 1996). A flexible thin-walled tube is convenient for restricting
and stopping the flow of seawater during the sampling. A length of the tube should be long enoughto reach from the petcock of the Niskin water sampler (or the bottom of the water sampling
bucket) to the bottom of the oxygen bottle.
5-1-3. Dispensers for pickling reagents
Prepare two plunger-type dispensers to add the pickling reagents I (4-1) and II (4-2) 1 mL each
into seawater in the oxygen bottle. The bottles for the dispensers (1 L) should also be lightshieldable to avoid degradation due to sunlight. The pickling reagent II will stick/bind to theplunger. In that case, soak it in hydroxylammonium chloride solution (about 200 g·L–1) and wash
out in the same way as the oxygen bottle. Disassembly of the dispenser before the soaking is
recommended when the fouling is severe. A total volume (2 mL) of the pickling reagent I and II
is included in the calculation of dissolved oxygen concentration. Therefore, high repeatability indispensing is required. The Poulten & Graf FORTUNA OPTIFIX® works well. In addition, thevolumes of the dispensers (Vreg [mL]) must be calibrated by the weighing at room temperature(Dickson et al., 2007).
5-1-4. Thermometer for water temperature
Prepare a battery-type digital thermometer with a thermistor on a thin flexible cable longenough to reach the bottom of the oxygen bottle. The thermistor is inserted into the oxygen bottle
for recording the temperature of the seawater during the sampling (6-8). The thermometer shouldmeasure the temperature to 0.1 °C and be calibrated by a comparison with a calibrated mercury
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thermometer. Specifically, compare the temperatures from the thermistor and the mercury
thermometer at several points in a temperature range of the seawater sample (usually 0–30 °C)
and calculate a regression equation between them.
5-1-5. DIW bottles
Plastic "squeeze" bottles (250 or 500 mL volume) filled with DIW are prepared to add DIW to
the neck of the oxygen bottle.
5-2. Titration apparatus
5-2-1. Photometric automatic titrator
A photometric automatic titrator (Fig. 1) optically detects the endpoint of the titration. The
titrator is equipped with a motorized microsyringe pump (piston burette) capable of discharging
5–10 mL of the sodium thiosulfate solution (4-4) by 1 μL of the minimum dose. The volume of
the burette must be calibrated by the weighing (Dickson et al., 2007). From the calibrations atseveral volumes between zero and the maximum capacity volume, a regression equation for thevolume calibration is calculated. The titration is automatically performed by monitoring theFig.1 Schematic view of photometric automatic titrator (modified from Kimoto Electric Co., LTD. (2009))
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absorbance at around 350–400 nm wavelength and finding the titration endpoint from the titration
curve optimized by the titration rate and stirring speed. The method of the endpoint calculation in
the titration program should be confirmed before the sample measurement. The automatic titration
can avoid human errors in the detection of the endpoint. An amperometric detector, instead of aphotometric one, can also determine the titration endpoint. There is no significant difference inanalytical results obtained using the amperometric and photometric automatic titrators (Langdon,2010).
5-2-2. Stirring bars
Use a rod-shaped magnet bar (25–30 mm) coated with fluororesin. One stirring bar is required
for each titration. Prepare enough number of the stirring bar cleaned and dried before use. If thestirring bar does not rotate smoothly in oxygen bottles, refrain from the use of these bottles that
may have a problem in the flatness of its bottom.
5-2-3. Dispenser for sulfuric acid solution
Prepare a dispenser for adding 1 mL of the sulfuric acid solution (4-3). Unlike the dispensers
for the pickling reagents (5-1-3), the volume calibration is not necessary because the dispensing
volume of the sulfuric acid solution added is not included in the calculation of dissolved oxygen
concentration. However, the concentration and volume of dispensing of the pickling reagents andthe sulfuric acid should not deviate from the targeted values by 5% and more because those aredetermined so that the sample pH in the titration become 2 (Carpenter, 1965a).
5-2-4. Burette for potassium iodate standard solution
To dispense 10 mL of the potassium iodate standard solution accurately (4-5), a motorized
automatic burette is recommended. The volume (10 mL, VKIO3 (t C )) must be calibrated by theweighing (Dickson et al., 2007) before use. It should be noted that the accurate dispensing of thestandard solution in the standardization (7-2) can reduce the uncertainty of the oxygen
measurement by the Winkler method.
5-2-5. Thermometers for water temperature
Prepare a calibrated thermometer for measuring the temperature of the potassium iodate
standard solution in the standardization (7-2). The thermometer for the measuring temperature of
the seawater sample (5-1-4) can also be used for this purpose. In addition, another thermometeris necessary for monitoring temperature of the sodium thiosulfate solution. You can use the
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thermometer for the seawater sample again or one attached to the automatic titrator (Fig.1). The
thermometer for the titrant solution is not necessary to be calibrated, because it only monitors the
temporal variation in the titrant temperature, which ensures the accurate measurement ofdissolved oxygen concentration.
5-2-6. DIW bottles
Prepare a plastic "squeeze" bottle (250 or 500 mL volume) filled with DIW or use the squeeze
bottle for the seawater sampling (5-1-5). Another empty squeeze bottle is used as a suction bottle
for DIW in the flared neck of the oxygen bottle.
5-2-7. Magnetic stirrer
A magnetic stirrer is equipped with the automatic titrator (5-2-1). If you have another one, theefficiency of the oxygen analysis is improved because you can prepare the next sample during themeasurement of the present sample.
6. Sampling
The seawater collected by the Niskin or other sampling devices (a bucket etc.) must betransferred into the oxygen bottle as soon as possible without exposure to air or change in thewater temperature. The seawater sample for dissolved oxygen must be collected before those fornon-gas samples when you also collect seawater samples for other elements. When the seawater
samples are collected from different depths using a multiple sampler, the sampling must start fromthe deepest sampler because the seawater sample in this sampler has undergone the greatest
change in temperature. The procedures of the collecting seawater from the water sampler into theoxygen bottle are as follows. When you use a bucket as a water sampler, prepare a longer water
sampling tube and siphon the seawater from the bottom of the bucket into the oxygen bottle
according to the following procedures. Never scoop up the seawater in the bucket by the oxygen
bottle.
6-1. Setup
Prepare a set of oxygen bottle/stopper (5-1-1), the dispensers of the pickling reagent solutions
I and II (5-1-3), the thermometer (5-1-4), the DIW bottle (5-1-5), and a field note at the sampling
location. A tube stand for the stoppers is useful. Keep the temperature of the pickling regent
solutions at room temperature by wrapping a heat-insulation sheet around the dispenser bottles
and avoiding exposure to direct sunlight. This is because the concentration of dissolved oxygen
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in the pickling reagent solutions, which is corrected in the calculating the dissolved oxygen
concentration, is assumed to be the saturated concentration at 25.5 °C (Murray et al., 1968).
6-2. Preparation of oxygen bottle
The oxygen bottles/stoppers should be dried. If you wet a bottle before the drawing accidentally,
use another dried one (Dickson, 1996). When dried bottles are not ready for use, it isrecommended to increase an overflow time (6-5) from two to three times of the bottle volume(Horibe et al., 1972).
6-3. Connection of water sampling tube
Connect the water sampling tube (5-1-2) to the nipple of the petcock on the Niskin sampler.
Open the vent screw and push the nipple down over the metal peg to start the flow of seawater.
Dislodge any air bubbles within the tube by tapping and squeezing.
6-4. Drawing
Squeeze the water sampling tube to stop the water flow, insert the tube all the way to the bottomof the oxygen bottle, and then gradually loosen the tube to start the water flow. Always keep the
tip of the tube at the bottom of the bottle and restrict the flow at the beginning to minimize thebubbles in the seawater and the surge on the surface of the seawater in the bottle.
6-5. Overflow
When the oxygen bottle is filled with the seawater, loosen the sampling tube and overflow theseawater by about the two bottle volumes. Do not allow water droplets to fall into the bottle fromoverhead stand flames for the Niskin water samplers during the overflowing. It is helpful for
estimating the overflow volume to measure how long it takes to fill the oxygen bottle. Ensure that
there are no bubbles inside the oxygen bottle, and then gently draw out the sampling tube. Just
before the tip of the sampling tube leaves the surface of the seawater, squeeze the tube to stop thewater flow completely. At that time, pay attention not to allow water droplets to drip from the tipof the sampling tube.
6-6. Stop of drawing
Pull the nipple of the petcock up to stop the seawater flow. Hold the neck of the oxygen bottle
and immediately carry it to where the dispensers of the pickling reagent solutions are located (orpass the bottle to a person who carries it there) before the temperature change of the seawater
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sample.
6-7. Addition of pickling reagents
Gently add 1 mL of the pickling reagent I and then 1 mL of the pickling reagent II. The nozzle
tip of the dispenser should be submerged at least 1 cm below the neck of the oxygen bottle before
the dispensing. Because the pickling reagent solutions are denser than seawater, they sink to thebottom of the oxygen bottle and a total of 2 mL of the seawater sample, which corresponds to thevolume of the pickling reagent solutions added, flows over from the oxygen bottle. Small air
bubbles in the nozzle of the dispenser should be flushed out by several times dispensing before
use. Droplets and stains on the nozzle should be wiped out using a wiping paper.
6-8. Temperature measurement and plugging
Immediately insert the thermometer into the seawater sample and note the sampling
temperature (tS [°C]) and the bottle number. The stopper is then inserted carefully in the oxygen
bottle. Do not wash a dried stopper with the sample seawater before insert. Turn over the bottle
and make sure that there are no air bubbles inside. If bubbles are contained, collect the seawater
sample again using another oxygen bottle. The seawater temperature just before the plugging isessential to accurate computing the density of the seawater sample in the oxygen bottle.
Meanwhile, it is necessary to shorten an interval between the overflow and plugging as much as
possible to minimize contamination from the atmospheric oxygen. For example, results from anexperiment with seawater whose dissolved oxygen concentration was low (about 100 μmol·L–1)
suggested that the oxygen concentration in the seawater sample plugged two minutes after theoverflow was about 0.3 % higher significantly than that plugged just after the overflow. Therefore,
when you collect seawater with a low dissolved oxygen concentration, it is recommended that the
sampling temperature (and the bottle number) is recorded during the overflow (6-5) using thethermometer and then the stopper is inserted immediately after the addition of the pickling
reagents.
6-9. Shaking
Shake the bottle vigorously about 20 times with "snapping of the wrist" to thoroughly mix theprecipitate using your thumb to secure the stopper. If the mixing is insufficient, the chemical
reaction between manganese hydroxide and dissolved oxygen does not complete, which results
in an error in the measurement.

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6-10. Storage
Add DIW to the neck of the oxygen bottle using the squeeze bottle. This creates a water sealand prevents oxygen contamination from the air during storage. Without DIW in the neck, the air
will penetrate the bottle inside through a narrow gap between the bottle and stopper, which may
increase oxygen concentration in the seawater sample. A mixing between the seawater sample inthe bottle and DIW in the neck through the gap, which may also result in the contamination ofdissolved oxygen, is restricted because of the difference in density between them. Store theoxygen bottles in a covered crate in an air-conditioned laboratory.
6-11. Second shaking and storage
A second shaking of the oxygen bottle is recommended approximately 30 minutes after the firstshaking in the same method as the first one to ensure that all the oxygen in the bottle has fully
reacted with the pickling reagents. Then, add DIW to the neck of the bottle again and store thebottles in the air-conditioned room before measurement. We found no significant difference in themeasurement results of a pair of seawater samples, whose dissolved oxygen concentration wasless than 200 μmol·L–1, with the shaking once and twice. However, the second shaking is effective
in preventing errors due to the wrong mixing in the first shaking. Meanwhile, it was reported that
dissolved oxygen concentration in the oxygen bottle turned over by accident just before themeasurement increased by about 1 %. This was probably because the manganese hydroxide
precipitate isolated by the anoxic supernatant seawater reacted with dissolved oxygen in the DIW
in the flared neck that had gradually penetrated into the bottle through the narrow gap between
the bottle and stopper. Therefore, the second shaking is not allowed a few hours after the firstshaking.
7. Analysis (titration)
Manganese hydroxide precipitate oxidized with dissolved oxygen is dissolved by theacidification, and iodine corresponding to dissolved oxygen is liberated. The liberated iodine
reacts with excess iodide ion and changes into triiodide ion, which is determined by titration withthe sodium thiosulfate solution. Therefore, to calculate the dissolved oxygen concentration in thesample, the concentration of the sodium thiosulfate solution must be determined in advance. Thisis called the standardization of the titrant solution. In addition, trace amounts of impurities,
including redox species, in the pickling reagents and sulfuric acid solution affects the titration
with the sodium thiosulfate solution. This interference by the impurities, which is called thereagent blank, should be determined prior to the sample measurement as well as thestandardization. In this section, we describe a method of the sample measurement (7-1) continued
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from the previous section, prior to those of the standardization (7-2), and the determination of thereagent blank (7-3).
7-1. Sample measurement
If the water seal by the DIW in the neck of the oxygen bottle is maintained, the bottle can be
stored for many days without any noticeable change in the oxygen concentration (Langdon, 2010).
We confirmed no significant change in the oxygen concentration within 72 hours. Usually thetitration can start from approximately a few hours after the sampling when the precipitate has
settled down at the bottom of the bottle. Before the measurement, check that the oxygen bottle
and the sodium thiosulfate solution are warmed up to room temperature.
7-1-1. Setup of automatic titrator
Place the sodium thiosulfate solution near the photometric automatic titrator (5-2-1) and draw
the solution into the flow tubes and piston burette of the titrator. No bubbles are allowed in them.
Immerse the thermometer (5-2-5) in the sodium thiosulfate solution and record its temperature. If
possible, a continuous monitoring of the solution temperature is recommended. Record theoxygen bottle number. Prepare the sulfuric acid solution.
7-1-2. Removal of DIW
Pour out the sealing DIW in the neck of the bottle using the empty squeeze bottle (5-2-7)
without disturbing the precipitate in the bottle and use a tissue or cotton ball to remove any
remaining water.
7-1-3. Addition of sulfuric acid
Remove the stopper from the oxygen bottle and pour 1 mL of the sulfuric acid into the bottle
along the stopper. Pour the remaining sulfuric acid solution on the stopper into the bottle using
DIW. If you pour the acid solution directly into the bottle, the precipitate may be disturbed.
7-1-4. Addition of stirring bar
Add a stirring bar (5-2-2) in the bottle without scatters of the seawater sample from the bottle.
Wipe the outside of the bottle with a tissue and set it in the bottle holder of the automatic titrator.

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7-1-5. Titration
Start the rotation of the stirring bar. After the rotation is stabilized (about 7 rps) and all the
precipitate are dissolved, start the automatic titration. Air bubbles generated by the faster rotationof the stirring bar could result in an error of the oxygen concentration determination because
atmospheric oxygen in the air bubbles oxidizes iodine ion to iodine. This interference, however,
hardly disturbs the endpoint determination if the titration time is less than 10 minutes because of
the slow reaction rate of this oxidization.
7-1-6. Record of results
The titration is automatically terminated. Record the titration endpoint (Vtit [mL]) and thetemperature of the sodium thiosulfate solution. If you find something unusual in the titration curve,
check whether the titration endpoint has been properly determined.
7-2. Standardization of sodium thiosulfate solution
The standardization of the sodium thiosulfate solution should be carried out at least twice, justbefore and after a series of sample measurements to verify that the concentration of the titrant
solution has not changed during the sample measurements. The standardization should be
performed after the titrant solution is warmed up to room temperature.
7-2-1. Setup of automatic titrator
Setup the automatic titrator as same as that in 7-1-1. Prepare the pickling reagents and sulfuric
acid solution.
7-2-2. Preparation of oxygen bottle
Fill an oxygen bottle approximately two thirds full with DIW and add a stirring bar into thebottle.
7-2-3. Addition of potassium iodate standard solution
Add 10 mL of the potassium iodate standard solution (4-5) to the oxygen bottle using thevolume-calibrated automatic burette (5-2-4). Immediately thereafter, measure the temperature of
the standard solution (tL [°C]) remaining in the brown glass bottle using the calibrated
thermometer (5-2-5) and record it.

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7-2-4. Addition of sulfuric acidAdd 1 mL of the sulfuric acid and stir thoroughly using the magnetic stirrer (5-2-6).
7-2-5. Addition of pickling reagent II
Add 1 mL of the pickling reagent II solution and stir thoroughly. The solution turns yellowish
due to liberated iodine.
7-2-6. Addition of pickling reagent I
Add 1 mL of the pickling reagent I solution and stir thoroughly. Fill the oxygen bottle up to theneck of it with DIW. If you add the pickling regent I prior to the reagent II, manganese hydroxide
precipitate locally produced in the bottle may cause the measurement errors.
7-2-7. Titration
Wipe the outside of the bottle and set it in the bottle holder of the automatic titrator. When thetitration is completed, check whether the titration curve and endpoint have been recorded. Record
the temperature of the sodium thiosulfate solution.
7-2-8. Calculation of endpoint
Repeat the above procedures 3 to 5 times and the endpoints are averaged (Vstd [mL]). Whenthe concentrations of the potassium iodate standard and sodium thiosulfate solutions are 1/600
mol·L–1 and 0.025 M, respectively, the titration volume (endpoint) of the sodium thiosulfate
solution is 4 mL, which corresponds to 250 μmol·kg–1 of dissolved oxygen concentration. The
calculation method of the concentration of the titrant solution from the titration volume isdescribed in section 8-2.
7-3. Reagent blank determination
The reagent blank should be determined at least twice, just before and after a series of sample
measurements to verify that it has not changed during the sample measurements, as well as thestandardization. The reagent blank determination should be also performed after the titrant
solution is warmed up to room temperature. Because the contribution of dissolved oxygen in the
pickling reagents is not included in this reagent blank, it is corrected by another way (8-3-1).

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7-3-1. Determination method
The reagent blank is the volume of the sodium thiosulfate solution required for the titration of
the interfering substances in the reagent solutions added. The reagent blank (Vblk [mL]) is obtained
as follows.
V1 = VP + Vblk

(10)

V2 = 2 ∙ VP + Vblk

(11)

Vblk = 2 ∙ V1 − V2(12)where V1 [mL] is the titration endpoint of the sodium thiosulfate solution for a volume (usually 1mL) of the potassium iodate standard solution, V2 [mL] is that for the precise double volume ofthe same standard solution, and Vp [mL] is the equivalent point of the titrant solution for thevolume of the standard solution. There are two specific methods. The standard solutions added
twice in an oxygen bottle are titrated sequentially, or the single and double volumes of the standard
solutions in two different oxygen bottles are titrated separately. In the former method, the total
volume of the sodium thiosulfate solution added in the first titration must be also recorded inaddition to the first endpoint. Here, we describe the latter method that requires the sameprocedures in the first and second titrations.
Strictly, the reagent blank determined by equation 12 (Vblk) is resulted not only from theinterfering substances in the reagents but also from the difference between the apparent and true
equivalent points due to unknown causes in the titrator (Carpenter, 1965b). This was suggested
by significant differences among the "reagent blanks" from an inter-laboratory experiment using
the same pickling reagents (Culberson, 1991). However, the temporal variation in this
instrumental error inherent to each titrator seems to be small. Therefore, there is no problem inthe calculation of the dissolved oxygen concentration using the apparent reagent blank. It is
possible to estimate the true reagent blank and instrumental error separately. A series of thereagent blank determinations with the pickling reagents of single, double, triple, and four times
volumes provides a regression line between the volume of the reagents added and the apparent
reagent blank. The true reagent blank and instrumental error are identical to the slope and yintercept of the regression line, respectively.
7-3-2. Setup of automatic titrator
Setup the automatic titrator as same as that in 7-1-1.

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7-3-3. Preparation of oxygen bottles
Fill two oxygen bottles approximately two thirds full with DIW and add a stirring bar into eachbottle.
7-3-4. Addition of potassium iodate standard solution
Add 1 and 2 mL of the potassium iodate standard solution into the first and second bottles,
respectively, using the volume-calibrated automatic burette. Because the volume of "2 mL" isrequired to be exactly the double of "1 mL", add "1 mL" twice into the second oxygen bottle.
Alternatively, you may add 2 and 4 mL of the standard solution into the first and second bottles,
respectively.
7-3-5. Addition of sulfuric acidAdd 1 mL of the sulfuric acid to the first oxygen bottle and stir thoroughly using the magnetic
stirrer.
7-3-6. Addition of pickling reagent II
Add 1 mL of the pickling reagent II solution and stir thoroughly. The solution turns yellowish
due to liberated iodine.
7-3-7. Addition of pickling reagent I
Add 1 mL of the pickling reagent I solution and stir thoroughly. Fill the oxygen bottle up to theneck of it with DIW.
7-3-8. Titration of first bottle
Wipe the outside of the bottle and set it in the bottle holder of the automatic titrator. When thetitration is completed, check whether the titration curve and endpoint (V1 [mL]) have beenrecorded. Record the temperature of the sodium thiosulfate solution.
7-3-9. Titration of second bottle
The second bottle with 2 mL of the standard solution is titrated along the same procedures fromsections 7-3-5 to 7-3-8 to obtain the endpoint (V2 [mL]).

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7-3-10. Calculation of reagent blank
The reagent blank is calculated by substituting V1 and V2 into equation 12. Repeat the above
procedures 3 to 5 times and the reagent blanks are averaged (Vblk [mL]).
8. Calculation of concentration
Dissolved oxygen concentration is calculated from the titration volume of the sodium
thiosulfate solution standardized with the potassium iodate standard solution. The calculation
methods for concentrations of the potassium iodate standard solution (8-1), sodium thiosulfate
solution (8-2), and dissolved oxygen in the seawater sample (8-3) are described below. It is
assumed that the concentration of the interfering substance in the DIW used in the reagent
preparation can be neglected.
8-1. Concentration of potassium iodate (KIO3) standard solution
8-1-1. Molal concentration (molality)
The molal concentration of the KIO3 standard solution CKIO3 [mol·kg–1] is expressed by thefollowing equation.

CKIO3 =

where

pKIO3 ∙wKIO3 ∙ fbuoy,KIO3
mKIO3 ∙ (wdw +wKIO3 ) ∙ fbuoy,dw(13)

pKIO3 : purity of KIO3,
wKIO3 : weight of KIO3 [g] (4-5-4),
fbuoy,KIO3 : factor of buoyancy correction (Dickson et al., 2007) for KIO3 weighing,
mKIO3 : molecular weight of KIO3 (= 214.001 [g·mol–1]),
wdw + wKIO3 : weight of DIW + KIO3 [kg] (4-5-5),
fbuoy,dw : factor of buoyancy correction (Dickson et al., 2007) for DIW + KIO3 weighing.

8-1-2. Molar concentration (molarity)
The molar concentration of the KIO3 standard solution at the temperature tL [°C] (7-2-3), CKIO3(tL) [mol·L–1] is expressed by the following equation.

CKIO3 (t L ) =CKIO ∙ ρw (tL)
3

1000

(14)

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where

CKIO3 : molal concentration [mol·kg–1] of KIO3 standard solution (8-1-1),
ρw (t L ) : density of DIW at temperature tL [kg·m–3] (Dickson et al., 2007). Strictly,
ρw (t L ) should be the density of the KIO3 standard solution. However, no significant

difference occurs when you use the density of DIW because it is a dilute solution (about
0.04%).
8-2. Concentration of sodium thiosulfate (Na2S2O3) solution
8-2-1. Dispensed volume of potassium iodate standard solution
The burette volume for the dispensing of the KIO3 standard solution depends on thetemperature of the standard solution, tL [°C] (7-2-3), which should be corrected. The dispensed
volume of the KIO3 standard solution at the temperature tL [°C], VKIO3 (tL) [mL] is calculated by
the following equation.
VKIO3 (t L ) = VKIO3 (t C ) ∙ {1 + αv (t L − t C )}
where

(15)

t C : temperature [°C] of DIW when burette volume was calibrated (5-2-4),
VKIO3 (t C ) : dispensed volume of KIO3 standard solution [mL] at temperature tC [°C],αV : coefficient of volumetric expansion of burette [K–1]. The coefficient of borosilicate
glass is approximately 1 × 10–5 K–1 (Japanese Industrial Standards, 1994).

8-2-2. Molar concentration (molarity)
Since 1 mole of potassium iodate corresponds to 6 moles of sodium thiosulfate (4-5), the molar
concentration of the sodium thiosulfate solution, CNa2 S2 O3 [mol·L–1] obtained by the following
equation.
CNa2 S2O3 = 6 ∙ CKIO3 (t L ) ∙ VKIO3 (t L )⁄(Vstd − Vblk )

where

(16)

CKIO3 (t L ): molar concentration of KIO3 standard solution [mol·L–1] at temperature tL[°C] (8-1-2),
VKIO3 (t L ): dispensed volume of KIO3 standard solution [mL] at temperature tL [°C] (8-2-1),
Vstd : average volume (endpoint) of Na2S2O3 solution used to titrate KIO3 standard

solution [mL] (7-2-8),
Vblk : average of reagent blank [mL] (7-3-10).
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8-3. Concentration of dissolved oxygen in sample
8-3-1. Amount of oxygen in sample
The total number of O2 moles in the seawater sample collected in the oxygen bottle, nsam [mol]is given by the following equation.

nsam =

where

V − Vblk1∙C∙ tit− DOreg
4 Na2 S2O3
1000

(17)

CNa2 S2O3 : molar concentration of Na2S2O3 solution [mol·L–1] (8-2-2),
Vtit : volume (endpoint) of Na2S2O3 solution used to titrate seawater [mL] (7-1-6),
Vblk : average of reagent blank [mL] (7-3-10),

DOreg: saturated amount of O2 at 25.5 °C in 2 mL of pickling reagent solutions I and II,
7.6 × 10–8 [mol] (Murray et al., 1968). Strictly, this should be calculated using thecalibrated volume of the pickling reagents added, Vreg [mL] (5-1-3). However, nosignificant difference occurs when you use "2 mL" because its contribution to thecalculation of the dissolved oxygen concentration is small.
Equation 17 is correct only when the molar concentrations of the Na2S2O3 solution, CNa2 S2 O3[mol·L–1] used in the sample measurement (7-1), standardization (7-2), and reagent blankdetermination (7-3) are equal. Therefore, the standardization and blank determination should be
carried out just before and after the series of the sample measurements, which allows reducing
temporal changes in the temperature and molar concentration of the Na2S2O3 solution. According
to equations 16 and 17, 1 mol of KIO3 corresponds to 1.5 mol of dissolved oxygen. Namely, theamount of KIO3 (about 16.7 μmol) used in the standardization of the Na2S2O3 solution (7-2)
corresponds to 25 μmol of O2, or the amount of O2 in 100 mL of seawater whose dissolved oxygen
concentration is 250 μmol·L–1.
8-3-2. Volume of oxygen bottle
The volume of the oxygen bottle at the sampling temperature tS [°C] (6-8), Vflask (tS) [mL] isobtained by the following equation.
Vflask (t s ) = Vflask (t c ) ∙ {1 + αv (t s − t c )}

where

(18)

t C : temperature [°C] of DIW when oxygen bottle volume was calibrated (5-1-1),
Vflask (t c ): volume of oxygen bottle [mL] at temperature tC [°C],

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αV : coefficient of volumetric expansion of the burette [K–1]. The coefficient ofborosilicate glass is approximately 1 × 10-5 K–1 (Japanese Industrial Standards, 1994).
8-3-3. Molar concentration (molarity)
The molar concentration of dissolved oxygen in the seawater sample at the sampling
temperature tS [°C], Csam(tS) [mol·L–1] is obtained by the following equation.
Csam (t s ) = 1000 ∙ nsam ⁄(Vflask (t s ) − Vreg )

where

(19)

nsam: amount of dissolved oxygen in seawater sample [mol] (8-3-1),
Vflask (t s ): volume of oxygen bottle [mL] at sampling temperature tS [°C] (8-3-2),
Vreg : calibrated volume of pickling reagents I and II added at room temperature [mL]

(5-1-3). The change due to temperature change is ignored.
8-3-4. Molal concentration (molality)
The conversion from the molar concentration (Csam(tS) [mol·L–1]) to the molal concentration(Csam [mol·kg–1]) is obtained by the following equation.
Csam = 1000 ∙ Csam (t s )⁄ρsam (t s , S)

where

(20)

tS: sampling temperature [°C] (6-8),
S: salinity of seawater sample,ρsam (t S , S): density [kg·m–3] of seawater sample with temperature tS [°C] and salinity S(Dickson et al., 2007).
9. Uncertainty
To evaluate the reliability of the measurement result (accuracy), the ideas of "precision" and"trueness" have been used. Because these ideas assume "measurement error" and "true value",
which are unknowable in principle, there has been confusion in the use of the terminology. In
1993, "Evaluation of measurement data - Guide to the expression of uncertainty in Measurement"
was published by seven international organizations including the International Organization forStandardization (ISO) (ISO, 2008). In this guide, the concept of "uncertainty" was introduced asa new indicator of the reliability of the measurement result. The "uncertainty" is defined as"parameter, associated with the result of a measurement, that characterizes the dispersion of thevalues that could reasonably be attributed to the measurement" and all the factors related to the
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reliability of the measurement are expressed as dispersion. The standard uncertainties (u1, u2, u3,…un), which are caused by all the factors, are combined in by the following equation.
uc = √∑ni=1(ui )2(21)

where uc is the combined standard uncertainty. Here we show an example of estimating theuncertainty of the measurement of dissolved oxygen concentration using the Winkler method.
9-1. Sources of uncertainty
From equations 17 and 19, the molar concentration Csam(tS) [mol·L–1] can be obtained by thefollowing equation.

1

Vtit − Vblk

4

1000

Csam (t s ) = 1000 ∙ ( ∙ CNa2 S2 O3 ∙where

− DOreg )⁄(Vflask (t s ) − Vreg ) (22)CNa2 S2 O3 : molar concentration of Na2S2O3 solution [mol·L–1],
Vtit : volume of Na2S2O3 solution used to titrate seawater [mL],
Vblk : average of reagent blank [mL],
DOreg: saturated amount of O2 at 25.5 °C in 2 mL of pickling reagent solutions,
7.6 × 10–8 [mol],Vflask (t s ): volume of oxygen bottle [mL] at sampling temperature tS [°C],
Vreg : calibrated volume of pickling reagents I and II added at room temperature [mL].

Because DOreg corresponds to about 1 μmol·kg–1 of dissolved oxygen concentration, its
contribution to the total uncertainty of dissolved oxygen concentration is negligible. The
uncertainty of Vreg is probably less than 1/50 of the Vflask (t s ) uncertainty. Thereby, we assume
that the uncertainty of the molar concentration of dissolved oxygen depends mainly on thosederived from CNa2 S2 O3 , Vtit , Vblk , and Vflask (t s ). If the uncertainty due to the seawater density
can be ignored, the uncertainties of the molar [mol·L–1] and molal [mol·kg–1] concentrations areequal.
9-2. Uncertainties of concentration of sodium thiosulfate solution and reagent blank
The molar concentration of the sodium thiosulfate solution, CNa2 S2 O3 is calculated by the molar
concentration of the KIO3 standard solution (CKIO3 (t L )), its dispensing volume (VKIO3 (t L )), thevolume of the Na2S2O3 solution used to titrate the KIO3 standard solution (Vstd ), and the reagent
blank (Vblk ) (8-2-2). The uncertainty of VKIO3 (t L ) , which is corrected appropriately using a
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calibrated electronic balance, seems to be smaller than that those from other sources. Therefore,
we assume that the uncertainty of CNa2 S2 O3 depends on those from CKIO3 (t L ), Vstd , and Vblk .
Equations 13 and 14 suggest that the uncertainty of CKIO3 (t L ) is mainly derived from those of
the purity of KIO3 (pKIO3 ), the molecular weight of KIO3 (mKIO3 ), and the weight of KIO3 (wKIO3 ).
When the certified standard substance "NMIJ CRM 3006-a" is used as the KIO3 standard, thestandard uncertainty due to its purity is 0.0090 %. The standard uncertainty of the molecularweight is about 0.0080%. The uncertainty of the reagent weighing using the calibrated electronicbalance is estimated to be about 0.027 %. Therefore, the combined standard uncertainty of
CKIO3 (t L ) is calculated to be 0.03 % by substituting the above three standard uncertainties into
equation 21. Meanwhile, the standard uncertainties of Vstd and Vblk can be estimated from thestandard deviation of the repeat measurements of the standardization (7-2) and reagent blankdetermination (7-3) to be about 0.001 mL and 0.002 mL, respectively. Then the standard
uncertainty of (Vstd − Vblk ) can be calculated to be 0.002 mL, which corresponds to 0.05 % of
the relative standard uncertainty. Finally, the combined standard uncertainty of CNa2 S2 O3 is
calculated to be approximately 0.06% from the relative standard uncertainties of CKIO3 (t L ) and(Vstd − Vblk ). Note that this uncertainty does not include the uncertainty derived from thetemporal change in temperature of the Na2S2O3 solution (8-3-1), because the temperaturedependency of the Na2S2O3 solution density is unknown. According to the temperaturedependency of pure water, the deviation of ±5 ºC from 20 ºC corresponds to about 0.1 % deviationof water density.
9-3. Uncertainty of sample titration
The standard uncertainty of Vtit can be derived from the standard deviation of themeasurements of the same sample pairs (replicate measurement). The standard deviation of thereplicate measurements (S) can be calculated from the difference between the two measurement
results of n pairs (d1, d2, d3,... dn).
S = √∑ni=1(di )2 ⁄2n(23)

The standard deviation is estimated to be about 0.1 μmol·kg–1, which corresponds to the standard
deviation of 0.002 mL (0.04 %) to 4 mL of titration (250 μmol·kg–1 of dissolved oxygen
concentration). The uncertainty of Vtit (0.002 mL) is larger than that of Vstd (0.001 mL, 9-2)
probably because of those derived from the seawater sampling (6). Then the standard uncertaintyof (Vtit − Vblk ) can be calculated to be 0.003 mL, which corresponds to 0.07 % of the relative
standard uncertainty.
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9-4. Uncertainty of oxygen bottle volume
The standard uncertainty of the oxygen bottle volume, Vflask (t s ) can be estimated from thestandard deviation of the repeat measurement in the bottle volume calibration (5-1-1), which is
calculated to be about 0.015 %.
9-5. Combined standard uncertainty
Finally, the combined standard uncertainty of the dissolved oxygen concentration is calculated
from the standard uncertainties of CNa2 S2 O3 (0.06 %, 9-2), (Vtit − Vblk ) (0.07 %, 9-3), andVflask (t s ) (0.015 %, 9-4) to be 0.09 %, which corresponds to the standard deviation of 0.23
μmol·kg–1 relative to 250 μmol·kg–1. Therefore, the expanded uncertainty (k = 2) is 0.18 % or
0.46 μmol·kg–1. The standard uncertainty of Vtit becomes larger when the dissolved oxygen
concentration is low. Therefore, you should pay much attention to the determination of Vtit toreduce the uncertainty of the dissolved oxygen measurement by the Winkler method. Note thatthe combined standard uncertainty (0.09 %) does not include those derived from the interfering
substances (10-2).
10. Traceability and interfering substances10-1. Traceability
Traceability is defined by "property of a measurement result whereby result can be related to areference through a documented unbroken chain of calibrations, each contributing to themeasurement uncertainty (ISO, 2015)". If you use "NMIJ CRM 3006-a" as a reference material,
the dissolved oxygen concentration measured using the Winkler method can be comparable. To
establish the comparability, an "unbroken chain of calibrations" should be planned. Fortunately,
the concentration of the KIO3 standard solution appropriately stored does not change for a few
years. When a batch of the KIO3 standard solution is changed, the standardization of the titrant
solution should be conducted with both new and old batches of the standard solution at the sametime so that you can cross-check the concentration of the new batch solution against that of theold one. It is also recommended a comparison between your standard solution and those preparedin other institutions.
Seawater includes several interfering substances for the measurement of dissolved oxygen
concentration by the Winkler method. The total concentration of the interfering substances, whichis converted into the dissolved oxygen concentration, is called the seawater blank concentration.
The determination of the seawater blank concentration is necessary for ensuring the traceabilityof the dissolved oxygen concentration. The seawater blank concentration in the open-ocean water
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is less than 1 μmol·kg–1 except those in suboxic and anoxic waters (10-2). If it is assumed that theconcentration is 0.50 (±0.50) μmol·kg–1 and the distribution of the possible values is uniform or
rectangular, its standard uncertainty is calculated to be 0.29 μmol·kg–1 (= 0.50/√3). This value
corresponds to the standard uncertainty of 0.12 % relative to 250 μmol·kg–1 of dissolved oxygen
concentration, which is larger than the standard uncertainty of 0.09 % derived from the othersources (9-5). The combined standard uncertainty, which includes the uncertainty of the seawater
blank concentration, is calculated to be 0.15 % or 0.37 μmol·kg–1 (the extended uncertainty is
0.30 % or 0.74 μmol·kg–1). Finally, it is necessary to subtract the seawater blank concentration(0.5 μmol·kg–1) from "the dissolved oxygen concentration", Csam (8-3-4).
10-2. Interfering substances
The major interfering substances in the open-ocean water are iodate ions, nitrite ions, andhydrogen peroxide. The total concentration of them, which is converted into the dissolved oxygen
concentration, is called the seawater blank concentration. In this section, a method for thedetermination of the seawater blank concentration (10-2-1), interferences by iodate ions (10-2-2),
nitrite ions (10-2-3), hydrogen peroxide (10-2-4), and others (10-2-5) are described.
10-2-1. Determination of seawater blank concentration
The seawater blank (Vsw-blk [mL]) is the volume of the titrant solution used to titrate theinterfering substances in the seawater sample and can be estimated by the following equations.

where

V1 = VP + Vblk

(24)

V3 = VP + Vsw−blk + Vblk

(25)

Vsw−blk = V3 − V1

(26)

V1: titration endpoint of Na2S2O3 solution for amount of KIO3 standard solution [mL],V3: titration endpoint of Na2S2O3 solution for amount of KIO3 standard solution andseawater sample [mL],
Vp: equivalent point of the titrant for amount of KIO3 standard solution [mL],
Vblk: reagent blank [mL].

V1 has been measured in the reagent blank determination (7-3). V3 can be obtained by similar
procedures of the reagent blank determination from sections 7-3-3 to 7-3-8, in which "DIW" isreplaced by "seawater sample". And sections 7-3-3 and 7-3-4 are revised as follows.
7-3-3r: "Fill an oxygen bottle with the seawater sample and measured water temperature (tS
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G301EN-28[°C]). The stopper is then inserted carefully in the oxygen bottle. Pour out and wipe off theseawater in the neck of the bottle. Remove the stopper and pour the remaining seawater on the
stopper into the bottle using DIW. Add a stirring bar".
7-3-4r: "Add 1 mL of the KIO3 standard solution into the oxygen bottle using the volumecalibrated automatic burette".
The seawater blank concentration Csw−blk (t s )[mol ∙ L−1 ] is calculated from the following
equation.

Csw−blk (t s ) =

where

1
∙C
∙V
(t )
⁄V
4 Na2 S2O2 sw−blk flask s(27)

CNa2 S2O3 : molar concentration of Na2S2O3 solution [mol·L–1] (8-2-2),
Vsw−blk : seawater blank [mL],
Vflask (t s ): volume of oxygen bottle [mL] at sampling temperature tS [°C] (8-3-2).

It would be impractical to determine the seawater blank concentration on each sample using
this method. It is recommended that investigators report the dissolved oxygen concentration
corrected by the assumed concentration of the seawater blank (0.5±0.5 μmol·kg–1) as shown insection 10-1 when they measure the oxygen concentration in the open-ocean water whose
seawater blank concentration is less than 1 μmol·kg–1. However, if you measured the dissolved
oxygen concentration using the Winkler method in coastal waters, in which the concentrations of
the interfering substances could be higher than those in the open-ocean water as shown below, theseawater blank concentration should be measured for the correcting of the oxygen concentration
at least once in a series of measurements. Anyway, when you report the concentration of dissolved
oxygen, you have to specify whether the seawater blank is corrected or not.
10-2-2. Iodate
The seawater blank in open-ocean water is mainly caused by iodate ions. Fig. 2 shows verticalprofiles of the seawater blank concentration in the subtropical area of the North Pacific Ocean,which were obtained by the method described in section 10-2-1. The concentrations in the surface(0–150 m) and deep (150 m–bottom) layers are 0.4–0.5 and 0.6–0.7 μmol·kg–1, respectively. On
the other hand, the concentration of iodate ion in the surface and deep layers are approximately
0.35 and 0.5 μmol·kg–1, respectively and their horizontal variations are small (Wong and Li, 2009).
In the Winkler method, 1.5 times of iodate concentration corresponds to the dissolved oxygen
concentration (8-3-1). Therefore, 0.35 and 0.5 μmol·kg–1 of iodate concentrations correspond to
0.52 and 0.75 μmol·kg–1 of dissolved oxygen concentrations, respectively, which are in good
agreement with the seawater blank concentrations shown in Fig. 2.
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Fig.2 Vertical profiles of the seawater blank concentration (μmol·kg–1) at stations in the subtropical areaof the North Pacific Ocean between November 2005 and January 2006. (a) 29.1°N/123.9°W, (b)25.5°N/164.3°W, (c) 24.2°N/172.8°E.

10-2-3. Nitrite
Nitrite ion oxidizes iodide ion to iodine in the acidic condition.
2NO2– + 2I– + 4H+ → I2 + 2NO + 2H2O

(28)

Because 1 mol of iodine corresponds to 0.5 mol of dissolved oxygen in the Winkler method, 1
mol of nitrite corresponds to 0.25 mol of dissolved oxygen. When dissolved oxygen is present in
the sample, the nitric oxide produced in equation 28 reacts with dissolved oxygen, and nitrite ion
is regenerated.
2NO + O2 + H2O → NO2– + NO3– + 2H+(29)

The regenerated nitrite ion oxidizes iodide ion again according to equation 28. Therefore, if thereactions of equations 28 and 29 proceed completely under the condition that there is enoughiodine ion and dissolved oxygen, the total reaction is summarized as follow.
NO2– + 2I– + 2H+ + O2 → I2 + H2O + NO3–(30)

In this case, 1 mol of nitrite corresponds to 0.5 mol of dissolved oxygen. According to results ofan experiment, the molar ratio of the concentrations of nitrite ion to dissolved oxygen is about
0.35 between 0.25 and 0.5 (Wong, 2012). In the open ocean, a maximum concentration of nitrite
up to about 1 μmol·kg–1 is observed in a subsurface layer. Therefore, the positive bias to dissolved
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oxygen concentration due to nitrite ion ranges between 0 and 0.35 μmol·kg–1 in the open ocean.
On the other hand, higher concentrations of nitrite ion (~10 μmol·kg–1) have been observed insuboxic areas such as the offshore area of Peru, where the interference in oxygen measurementby nitrite ion could be a few μmol·kg–1.
The interference by nitrite ion can be prevented by adding sodium azide (NaN3) to the pickling
reagent (Barnett and Hurwitz, 1939).
3N3– + NO2– + 4H+ → 5N2 + 2H2O

(31)This method is called "the modified Winkler method with sodium azide" and commonly used in
the determination of dissolved oxygen concentration in industrial wastewater with highconcentration of nitrite (Japanese Industrial Standards, 2013). The procedures of the modified
method are the same as the original method except that 10 g of sodium azide is added to 1 L of
the pickling reagent II solution (4-2). According to Wong (2012), there is no significant difference
in results of oxygen concentration measurements between the modified and original Winkler
methods. If you measured dissolved oxygen concentration in seawater with a high concentrationof nitrite, the modified Winkler method is recommended. However, the solutions and wastes withsodium azide must be handled with care because it is toxic.
10-2-4. Hydrogen peroxide
Hydrogen peroxide is a positive interfering substance in the measurement of dissolved oxygen
concentration using the Winkler method as same as iodate and nitrite ions. Hydrogen peroxide
oxidizes iodide ion to iodine in the acidic condition.
H2O2 + 2I– + 2H+ → I2 + 2H2O

(32)

Because 1 mole of iodine corresponds to 0.5 mole of dissolved oxygen in the Winkler method, 1
mole of hydrogen peroxide corresponds to 0.5 mole of dissolved oxygen. Although the rate of thischemical reaction is slow in DIW, hydrogen peroxide can interfere with the Winkler method
because manganese ions (Mg2+) in the pickling reagent facilitate the reaction as a catalyst (Wonget al., 2010). Hydrogen peroxide is mainly generated by the photochemical reaction of organic
matter in the surface layer. As a result, the concentrations in the surface and deep layers in the
open ocean are 0.06–0.3 μmol·kg–1 and less than 0.01 μmol·kg–1, respectively (Wong et al., 2010),
which correspond to up to 0.15 μmol·kg–1 of dissolved oxygen concentration. The interference byhydrogen peroxide is smaller than those by iodate and nitrite ions in the open ocean. However,
you should pay much attention to the seawater blank in seawaters collected in coastal areas andGuideline of ocean observations Vol. 3 Chap. 1 Dissolved Oxygen© Yuichiro KUMAMOTO, Daisuke SASANO, Hironori SATO, Keitaro MATSUMOTO 2019
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estuaries, where more than 1 μmol·kg–1 of hydrogen peroxide concentrations have been observed(Wong et al., 2010).
10-2-5. Others
In anoxic water depleted of dissolved oxygen, sulfuric acid is reduced to sulfite acid and sulfide.
In addition, metallic ions may be eluted from sea-floor sediments into the anoxic bottom wateron the seafloor. Sulfite ions, sulfides, and metallic ions are also the interfering substances of the
Winkler method. In addition, there are other problems such as contamination from atmospheric
oxygen during the water sampling and difficulty in the determination of the titration endpoint for
the trace amount of oxygen. Therefore, it would be impractical to measure dissolved oxygen
concentration less than 1 μmol·kg–1 using the Winkler method.
References
Barnett, G. R. and E. Hurwitz (1939): The use of sodium azide in the Winkler Method for the determinationof dissolved oxygen, Sewage Works Journal, 11, 781–787.
Broenkow, W. W. and J. D. Cline (1969): Colorimetric determination of dissolved oxygen at low
concentrations, Limnology and Oceanography, 14, 450–454.
Carpenter, J. H. (1965a): The Chesapeake Bay Institute technique for the Winkler dissolved oxygen method.
Limnology and Oceanography, 10, 141–143.
Carpenter, J. H. (1965b): The accuracy of the Winkler method for dissolved oxygen analysis. Limnology
and Oceanography, 10, 135–140.
Culberson, C. H. (1991): Dissolved Oxygen. In WOCE Operations Manual, Part 3.1.3 : WHP Operations
and Methods, WHP Office Report WHPO 91-1, WOCE Report No. 68/91. Available online at:
http://www.nodc.noaa.gov/woce/woce_v3/wocedata_1/whp/manuals.htm.
Culberson, C. H., G. Knapp, R. T. Williams, and F. Zemlyak (1991): A comparison of methods for thedetermination of dissolved oxygen in seawater, WHP Office Report WHPO 91-2, WOCE Report No.
73/91. Available online at: http://darchive.mblwhoilibrary.org/bitstream/handle/1912/243/WHPO-912.pdf?sequence=1&isAllowed=y
Dickson, A. G. (1996): Determination of dissolved oxygen in sea water by Winkler titration. In WOCE
Operations Manual, Part 3.1.3 : WHP Operations and Methods, WHP Office Report WHPO 91-1,
WOCE Report No. 68/91.
Available online at: http://www.nodc.noaa.gov/woce/woce_v3/wocedata_1/whp/manuals.htm.
Dickson, A. G., C. L. Sabine, and J. R. Christian (2007): Guide to best practices for ocean CO2
measurements. PICES Special Publication 3, North Pacific Marine Science Organization, Sidney, pp.
191.
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Fujifilm Wako Pure Chemical Corporation (2018): 0.01mol/l Sodium Thiosulfate Solution. Available
online at: http://www.siyaku.com/uh/Shs.do?dspWkfcode=19105565&_ga=2.197871663.122721241.1534985899-1808556025.1534985899 (in Japanese).
Grasshoff, K. (1976): 4. Determination of oxygen, p. 59‒70. In Methods of Seawater Analysis, first edition,edited by K. Grasshoff, Verlag Chemie, Weinheim.
Hansen, H. P. (1999): 4. Determination of oxygen, p. 76‒89. In Methods of Seawater Analysis, third,
completely revised and extended edition, edited by K. Grasshoff, K. Kremling, and M. Ehrhardt,
WILEY-VCH, Weinheim.
Horibe, Y., Y. Kodama, and K. Shigehara (1972): Errors in sampling procedure for the determination ofdissolved oxygen by Winkler Method. Journal of Oceanographical Society of Japan, 28, 203–206.
ISO (2008): ISO/IEC Guide 98-3:2008, Uncertainty of measurement Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995). Available at:
http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=50461
ISO (2015): Guide 30:2015 Reference materials -- Selected terms and definitions. Available at:
http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=46209
International Union of Pure and Applied Chemistry (1997): Compendium of Chemical Terminology, 2nded. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific
Publications, Oxford. Available online at: http://goldbook.iupac.org/
Japanese Industrial Standards (1994): Glass apparatus for chemical analysis, JIS-R3503. Available online
at: http://kikakurui.com/r3/R3503-2007-01.html (in Japanese).
Japanese Industrial Standards (2013): Current of testing method for industrial wastewater, JIS-K0102.
Available online at: http://kikakurui.com/k0/K0102-2013-01.html (in Japanese).
Japan Meteorological Agency (1999): the Manual on Oceanographic Observation Part 1, Japan
Meteorological Agency, Tokyo, 200 pp (in Japanese).
Joint Global Ocean Flux Study (1994): Chapter 6. Determination of dissolved oxygen by Winkler procedure,
p. 25‒33. In JGOFS Protocols. Available online at: http://usjgofs.whoi.edu/JGOFS_19.pdf.
Kimoto Electric Co., LTD. (2009): Manual of Titrator for Dissolved Oxygen DOT-05, 60pp. Available
online at: http://www.kimoto-electric.co.jp/support/pdf/DOT05_manual.pdf (in Japanese).
Kitano, Y. (1964): Determination of dissolved oxygen concentration in freshwater and seawater.

"Bunsekikagaku", 13, 573–577 (in Japanese).
Kumamoto, Y., Y. Takatani, T. Miyao, H. Sato, K. Matsumoto (2015): Dissolved Oxygen, p. G301JP:001‒
030. In Guideline of Ocean Observations Volume 3 Seawater Analysis (Dissolved Substances), The
Oceanographic Society of Japan, Tokyo (in Japanese).
National Metrology Institute of Japan (2015): NMIJ CRM 3006-a. https://www.nmij.jp/service/C/ (inJapanese).

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Labasque, T., C. Chaumery, A. Aminotc, and G. Kergoat (2004): Winkler determination of dissolved
oxygen: re-examination of critical factors and reliability, Marine Chemistry, 88, 53–60.
Langdon, C. (2010): Determination of dissolved oxygen in seawater by Winkler titration using theamperometric technique. In the GO-SHIP Repeat Hydrography Manual: A Collection of Expert Reports
and Guidelines, edited by E. M. Hood, C. L. Sabine, and B. M. Sloyan, ICPO Publication Series Number
134. Available online at: http://www.go-ship.org/HydroMan.html.
Miyao, T., S. Umeda, Y. Takatani, N. Nagai (2013): High-precision determination of dissolved oxygen.
Weather Serv. Bull., 80, S149‒S157 (in Japanese).
Murray, C. N., J. P. Riley, and T. R. S. Wilson (1968): The solubility of oxygen in Winkler reagents used
for the determination of dissolved oxygen. Deep-Sea Research, 15, 237–238.
Pai, S.-C., G.-C. Gong, and K.-K. Liu (1993): Determination of dissolved oxygen in seawater by direct
spectrophotometry of total iodine, Marine Chemistry, 41, 343–351.
Strickland, J. D. H. and T. R. Parsons (1972): A Practical Handbook of Seawater Analysis. Fisheries
Research Board of Canada, Ottawa, 310 pp.
Tanaka, T., H. Hayashi, Y. Komiya, H. Nabekawa, H. Hayashi (2007): Stability of sodium thiosulfate
solution and constant-current coulometric iodometric titration od potassium iodate, "Bunsekikagaku",
56, 327–332 (in Japanese with English abstract).
Winkler, L. W. (1888): Die Bestimmung des in Wasser gelösten Sauerstoffen. Berichte der Deutschen
Gesellschaft, 21, 2843–2854.
Wong, G. T. F. (2012): Removal of nitrite interference in the Winkler determination of dissolved oxygenin seawater, Marine Chemistry, 130-131, 28–32.
Wong, G. T. F. and K.-Y. Li (2009): Winkler's method overestimates dissolved oxygen in seawater: Iodate
interference and its oceanographic implications, Marine Chemistry, 115, 86–91.
Wong, G. T. F., Y.-C. Wu, and K.-Y. Li (2010): Winkler's method overestimates dissolved oxygen innatural waters: Hydrogen peroxide interference and its implications, Marine Chemistry, 122, 83–90.

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The precise and accurate determination of dissolved inorganic
nutrients in seawater, using Continuous Flow Analysis methods○Michio AOYAMA(Japan Agency for Marine-Earth Science and Technology and University of Tsukuba)

An original version of GO-SHIP nutrients manual by Hydes et al. (2010) is revised and new nutrients
manual was published in August 2019 as “The precise and accurate determination of dissolved inorganic
nutrients in seawater, using Continuous Flow Analysis methods” by Becker et al. (2019).
This revised manual reviews basic sample collection and storage, aspects of continuous flow
analysis (CFA) using an Auto-Analyzer, and specific nutrient methods in use by many laboratories doing
repeat hydrography. The document also covers laboratory best practices including quality control andquality assurance (QC/QA) procedures to obtain the best results, and suggests protocols for the use ofreference materials (RM) and certified reference materials (CRM). This revised manual was scientificpublic comments procedure in 2018 and all comments were incorporated where appropriate.
The revised GO-SHIP manual is available at the following website:

http://www.go-ship.org/HydroMan.html. DOI: http://dx.doi.org/10.25607/OBP-555

References
D. J. Hydes, M. Aoyama, A. Aminot, K. Bakker, S. Becker, S. Coverly, A. Daniel, A. G. Dickson, O. Grosso,
R. Kerouel, J. van Ooijen, K. Sato, T. Tanhua, E. M. S. Woodward, J. Z. Zhang (2010): Determination of
Dissolved Nutrients (N, P, SI) in Seawater with High precision and Inter-Comparability Using GasSegmented Continuous flow Analysers. In: The Go-ship Repeat Hydrography Manual: A Collection ofExpert Reports and Guidelines, UNESCO-IOC, IOCCP Report Number 14, ICPO Publication Series
Number 134
S. Becker, M. Aoyama E. Malcolm S. Woodward, K. Bakker, S. Coverly, C. Mahaffey, T. Tanhua, (2019):.
The precise and accurate
determination of dissolved inorganic nutrients in seawater, using Continuous

Flow Analysis methods. In: The GO-SHIP Repeat Hydrography Manual: A Collection of Expert Reports
and Guidelines. Available online at: http://www.go-ship.org/HydroMan.html.
DOI: http://dx.doi.org/10.25607/OBP-555

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Trace metals‫ۑ‬Hajime Obata (AORI, Univ. Tokyo)

For determination of trace metals in seawater, contamination is one of the most critical problems.
Concentrations of most metals are very low in seawater of open ocean, but the metals are ubiquitous in
the research ship and laboratories. We need to be very careful to avoid contamination at each step,collection, filtration, pretreatment, and analysis of seawater. In this chapter, clean techniques for eachstep are described to prevent the contamination. Clean sampling techniques are described in Vol. 2,
Chap. 1, “Clean sampling”.
1. Filtration of seawater
We usually study “dissolved” trace metals because dissolved fraction of bioactive trace metals inseawater is considered to be available for marine microorganisms. This “dissolved fraction” is also
investigated on other non-bioactive trace metals. Filtration of seawater samples is necessary to obtain
the dissolved fraction of the samples, but we often suffer from contaminations during this process. To
avoid the contamination, initially we have to confirm that the materials of filters and filtering apparatuses
are clean enough for the target metals, and establish their cleaning method. For example, 0.2 or 0.4 Pm
pore-size Nucleopore filters are frequently used to filter seawater samples for trace metal analyses, butthese filters must be cleaned with diluted ultra-pure grade of acids before use. During the cleaning
process, the acids remaining in the filters may cause the contamination of the seawater samples. The
remaining acids should be removed thoroughly with ultra high purity water (UHPW). Filtering
apparatuses, like filter holders, are usually made of Teflon, polycarbonate or polysulfon. Suitablecleaning methods for the materials should be established not to damage the apparatuses.
Capsule filters are easy to handle and frequently used for filtration. For example, many researchgroups in the international GEOTRACES project use 0.2 Pm pore-size polysulfon capsule fiters(Acropak, PALL). To clean the filters, we fill the capsule filters with 0.1 M ultra pure hydrochloric acidfor one day. The acid solution should be completely removed by passing UHPW through the capsulefilters. We can effectively remove the acid solution by filling the capsule filters with UHPW for morethan one day. Onborad the research vessel, one capsule filter is repeatedly used throughout theobservation at several stations. In this case, to prevent the growth of bacteria inside of the capsule, thefilters are preserved in the refrigerator between the stations.
2. Onboard analyses
For studying the marine biogeochemistry of contamination-prone trace metals, it is better todetermine them onboard the ship. Onboard analyses will allow us to notice the contamination, which
prevents the damage to the entire samples during the cruise. In GEOTRACES project, it is recommended
to determine some contamination-prone trace metals like Fe and Zn in seawater onboard the ship. Since
the clean laboratory space is limited in the research ship, we should apply the compact closed flow
system for the analytical method. Several methods have already been developed for onboard analysesof trace metals in seawater (e.g. Al, Brown & Bruland, 2008. Fe: Lohan et al., 2006; Measures et al.,
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G303EN-2

1995; Obata et al., 1993. Zn: Gosnell et al., 2012; Jakuba et al., 2008; Lohan et al., 2003). Onboard
analyses often enable the in situ determination of each species of trace metals in seawater. Therefore, itwould be also better to determine trace metals, whose speciations are easily variable, onboard the ship.
3. Preservation and prereatments
Some trace metals in seawater will be measured after coming back to the land-based laboratory.
Especially, some metals and their isotopes will be determined by using large-sized anlytical facilities,
so that we have to establish the preservation methods of the samples without loss and contamination.
Many trace metals are easily adsorbed onto the wall of the storing bottles at neutral to alkaline pH
conditions. An optimal pH of seawater sample for preservation should be examined for each target metalin the laboratory. For most of the metals, it is better to lower the pH of the samples to less than 2 withhydrochloric acid or nitric acid. Since inpirities in the acids directly cause contaminations, we need tocheck the blank values of the acids before use. If the samples are preserved for a long time, leachates of
the target metals from the stored bottles should also be evaluated. By choosing the optimal material forthe storing bottles and establishing their cleaning methods, we can preserve the seawater samples for along time. During the production of polymers, some metals might be added to the material as catalysts.
We need to examine which storing bottles are suitable for the target metals. For many trace metals, lowdensity polyehylene or Teflon bottles are known to be useful for storage.
On the other hand, by lowering the sample pH, the speciation of metals will be changed in seawater.
In this case, we can temporally preserve the seawater samples by freezing at lower than -18 degree (e.g.,
Buck et al., 2012). However, we should not use dry ice for freezing because the pH of samples might bechanged. It would be better to examine how long we can preserve the samples.
4. Analyses at land-based laboratory
Many anlytical methods have been developed to determine trace metals in seawater at land-basedlaoratory (Sohrin and Bruland, 2011). To determine many trace metals simultaneously, inductively
coupled plasma mass spectrometry (ICP-MS) is frequently used. In the ICP-MS system, a hightemperature ICP source converts the atoms of the target metals to their ions. The produced ions are
introduced to the mass spectrometer where the ions are separated and detected. The ions are separated
by their mass-to-charge ratio with the quadrupole mass filter. This quadrapole mass filter can sufficiently
resolve the mass-to-charge ratios of heavy elements, but this resolution is not enough to separate
overlapping molecular or isobaric interferences from the isotopes of some trace metals (e.g., Fe, Cu andZn). To obtain higher resolution, magnetic sector mass spectrometers are common in ICP-MS, whichallow us to eliminate or reduce the effect of interferences.
Since seawater contains so much sea-salts, it is difficult to introduce seawater samples to ICP-MS
directly. We have to separate target metals from the sea-salts before ICP-MS analyses. For thisseparation, several methods have been developed, such as magnesium hydroxide coprecipitation method
and chelating resin preconcentration method. During these preconcentration processes, the samples are
possibly contaminated, hence the processes should be performed under clean air condition or within theflow system. Moreover, the isotope dilution method, adding enriched isotope spike solution, is applied
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G303EN-3

for the precise measurement. We should select suitable methods for the target metals.
Recently, many methods have been developed by combining ICP-MS with preconcentration using
chelating resion column. Among these methods, several methods, often used, are shown in the tablebelow. To successfully determine trace metals in seawater, the analysts should have high levels ofanalytical skill and experience for clean sample handling. For example, we should check whether
procedual blank values are low enough to measure the concentration level in oceanic water.
5. Reference seawater sample

Before determination of trace metals in seawater samples, we usually examine the precision of theanalytical methods. Moreover, to get the right number, it is required to analyze reference seawaters andreport the results. It is beter to choose and analyze reference seawaters in which the concetrations of thetarget metals are as the same level as those in actual samples. As reference seawaters, consensus values
should be reported by several different groups with different methods. We can commercially obtainsome reference seawaters, like NASS-series (National Research Council Canada). In these reference
seawaters, the concentrations of trace metals are a little higher than those in Atlantic Ocean, Southern
Ocean, Indian Ocean and Pacific Ocean. In the international GEOTRACES project, reference seawaters
for main key parameters are widely distributed with their consensus values (e. g. SAFe, GEOTRACES
seawaters) and available for Geotracers. The details of the reference seawaters are shown at the web site(http://es.ucsc.edu/~kbruland/GeotracesSaFe/kwbGeotracesSaFe.html). However, this distribution to
the wide community is a voluntary work and the numbers of stocked seawaters are limited. Hence, thereference seawaters cannot be provided everlastingly. It is not easy to keep the reference seawaters fora long time at the same quality level. We will have to find the way to distribute the high-quality reference
seawater continuously.

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References
Biller, D. V., and K. W. Bruland (2012): Analysis of Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in seawater using the
Nobias-chelate PA1 resin and magnetic sector inductively coupled plasma mass spectrometry (ICP-MS).
Mar. Chem., 130-131, 12–20.
Buck, K. N., J. Moffett, K. A. Barbeau, R. M. Bundy, Y. Kondo, and J. Wu (2012): The organic complexation ofiron and copper: an intercomparison of competitive ligand exchange–adsorptive cathodic stripping
voltammetry (CLE-ACSV) techniques. Limnol. Oceanogr.: Methods, 10, 496–515.
Brown, M.T. and K. W. Bruland (2008): An improved flow-injection analysis method for the determination ofdissolved aluminium in seawater. Limnol. Oceanogr.: Methods, 6, 87-95.
Gosnell, K.J., W. M. Landing, A. Milne (2012): Fluorometric detection of total dissolved zinc in the southern
Indian Ocean. Mar. Chem., 132-133: 68-76.
Jakuba, R.W., J. W. Moffett, and M. A. Saito (2008): Use of a modified, high-sensitivity, anodic stripping
voltammetry method for determination of zinc speciation in the North Atlantic Ocean. Anal. Chim. Acta,
614, 143-152.
Lagerström, M. E., M.P. Field, M. Séguret, L. Fischer, S. Hann, R.M. Sherrell (2013): Automated on-line flowinjection ICP-MS determination of trace metals (Mn, Fe, Co, Ni, Cu and Zn) in open ocean seawater:
Application to the GEOTRACES program. Mar. Chem., 155, 71–80.
Lee, J.M., E. A. Boyle, Y. Echegoyen-Sanz, J. N. Fitzsimmons, R. Zhang, R. A. Kayser, (2011): Analysis oftrace metals (Cu, Cd, Pb, and Fe) in seawater using single batch nitrilotriacetate resin extraction and isotope
dilution inductively coupled plasma mass spectrometry. Anal. Chim. Acta, 686, 93–101.
Lohan, M. C, D. W. Crawford, D. A. Purdie, P. J. Statham (2003): Iron and zinc enrichments in the northeastern
subarctic Pacific: Ligand production and zinc availability in response to phytoplankton growth. Limnol.
Oceanogr., 50, 1427-1437.
Lohan, M.C., A. M. Aguilar-Islas, K. W. Bruland (2006): Direct determination of iron in acidified (pH 1.7)
seawater samples by flow injection analysis with catalytic spectrophotometric detection: Application andintercomparison. Limnol. Oceanogr.: Methods, 4, 164-171.
Measures, C. I., J. Yuan, J. A. Resing (2005): Determination of iron in seawater by flow injection analysis using
in-line preconcentration and spectrophotometric detection. Mar. Chem., 50, 3-12.
Milne, A., W. Landing, M. Bizimis, P. Morton (2010): Determination of Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb inseawater using high resolution magnetic sector inductively coupled mass spectrometry (HR-ICP-MS). Anal.
Chim. Acta 665, 200–207.
Minami, T., W. Konagaya, L. Zheng, S. Takano, M. Sasaki, R. Murata, Y. Nakaguchi, Y. Sohrin (2015): An offline automated preconcentration system with ethylenediaminetriacetate chelating resin for the determinationof trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry. Anal. Chim.
Acta, 854,183–190.
Obata, H., H. Karatani, E. Nakayama (1993): Automated determination of iron in seawater by chelating resin
concentration and chemiluminescence detection. Anal. Chem., 65, 1524-1528.

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Sohrin, Y., S. Urushihara, S. Nakatsuka, T. Kono, E. Higo, T. Minami, K. Norisuye, S. Umetani (2008):
Multielemental determination of GEOTRACES key trace metals in seawater by ICPMS after
preconcentration using an ethylenediaminetriacetic acid chelating resin. Anal. Chem., 80, 6267–6273.
Sohrin, Y. and K. W. Bruland (2011): Global status of trace elements in the ocean. Trends in Anal. Chem., 30,
1291-1307.

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DIC
A Standard Operation Protocol of “Determination of total dissolved inorganic carbon in sea water”
is available from the following CDIAC web site:
http://cdiac.ornl.gov/ftp/oceans/Handbook_2007/sop02.pdf
http://cdiac.ornl.gov/oceans/Handbook_2007.html

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Determination of total alkalinity
in sea water by spectrophotometry‫ۑ‬Masao ISHII and Naohiro KOSUGI (Meteorological Research Institute, JMA)

1. Scope
This procedure describes a method for the determination of total alkalinity in sea water byspectrophotometry. A method for the determination of total alkalinity by potentiometric titration has
been described in SOP 3a and SOP 3b in Chapter 4 of Dickson, A.G., Sabine, C.L. and Christian, J.R.
(Eds.) 2007, “Guide to best practices for ocean CO 2 measurements. PICES Special Publication 3, 191
pp. (http://cdiac.ornl.gov/oceans/Handbook_2007.html). The method is suitable for assaying oceaniclevels of total alkalinity (2000–2500 ȝmol kg–1).
2. Terms and definition
The total alkalinity of a sea water sample is defined as the number of moles of hydrogen ion
equivalent to the excess of proton acceptors (bases formed from weak acids with a dissociation constant
K –4.5 at 25°C and zero ionic strength) over proton donors (acids with K > 10–4.5) in 1 kilogram ofsample: AT =[HCO 3 -] + 2[CO 3 2-] + [B(OH) 4 -] + [OH-] + [HPO 4 2-]+ 2[PO 4 3-] + [SiO(OH) 3 -] + [NH 3 ] + [HS-] + …
– [H+] F – [HSO 4 -] – [HF] – [H 3 PO 4 ] – …

(1)

Brackets represent total concentrations of these constituents in solution, [H+] F is the free
concentration of hydrogen ion, and the ellipses represent additional minor acid or base species that areeither unidentified or present in such small amounts that they can be ignored.
3. Principle
A known amount of sea water is placed in a container such as beaker or directly in an optical cell
where it is first acidified to a pH between 3.8 and 4.2 with a known amount of hydrochloric acid. The
acid titrant is made up in a sodium chloride background to approximate the ionic strength of sea water
so as to maintain approximately constant activity coefficients during the measurement procedure. The
solution of an indicator dye bromocresol green is also added to the sea water sample. The solution isthen stirred for a period of time to allow for the escape of CO 2 that has evolved, and subsequently pHof the sample is measured precisely with spectrophotometric technique. Total alkalinity is computedfrom the volume of sample (V SW /dm3), concentration (c HCl / mol dm-3) and volume (V HCl /dm3) ofhydrochloric acid titrant added to the sample, [H+] T (=10-pH), and the density of sea water sample whenplaced in the container (ȡ SW / kg dm-3):

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AT

cHCl  VHCl  106  [H  ]T  (VSW  VHCl )  USW.
VSW  USW(2)

It is necessary to measure the temperature of sample when it is placed into the container and when
spectrophotometric measurement is made in order to compute the density of sea water sample and tocorrect for the effect of temperature change on spectrophotometric measurements.
4. Apparatus
4-1 An example of apparatus set-up

An example of apparatus set-up is shown in Figure 1. Usually, hydrochloric acid and indicator dye
are added in a beaker, and spectrophotometric measurement is made in an optical cell separately.
However, in an example shown here, measurements are made precisely and efficiently by adding amixed solution of acid titrant and indicator dye to a seawater sample and making spectrophotometricmeasurement in the same cell in a spectrophotometric system that uses optical fibers.

Figure 1 Schematic diagram of an apparatus to determine total alkalinity in sea water.

4-2 Transferring sea water sample

Volumetric pipette (~50 cm3) is used to transfer sea water sample from a sample bottle into an opticalcell (or beaker). In Figure 1, water-jacketed volumetric pipette with stopcocks at both ends are used tokeep the sample temperature unchanged during the transfer. The pipette needs to be calibrated prior touse. In order to obtain the highest quality results with repeatability of total alkalinity analysis at around
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G305EN-3±1 ȝmol kg-1, it is necessary to measure the temperature of the sea water sample within the uncertainty
of ±0.1°C.
4-3 Beaker or optical cell

Hydrochloric acid and indicator dye (it is convenient to use their mixed solution) are added to a sea
water sample in a beaker or in an optical cell. It is then stirred and stripped of CO 2 with a stream of N 2
gas.
4-4 Addition of hydrochloric acid and indicator dye solution

Hydrochloric acid (and indicator dye) is added to a sample seawater using a dispensing burette withits dispensing volume of 5 cm3 at its maximum. In order to obtain the highest quality results, it isnecessary to use a highly reproducible burette (±0.001 cm3). Although such a burette is commerciallyavailable, its accuracy is typically not as good, and the burette system must be also calibrated prior touse. It is also recommended to keep the temperature of the acid unchanged.
The concentration of hydrochloric acid shifts as it is used and thereby the head space in the bottle
increases. To minimize the change, the room air is introduced into the head space of the bottle after itflows through the same hydrochloric acid stored in another bottle.
4-5 Aeration of acidified sea water sample

Cylinder of N 2 gas mounted with pressure regulator and a flowmeter to indicate gas flow rate (ca.
200 cm3 min–1) is used to remove CO 2 from the acidified sea water sample.
4-6 Spectrophotometer and optical cell

Absorbances of the acidified seawater in an optical cell and deionized water in a reference cell aremeasured at wavelengths of 444nm, 616nm and 750nm with a spectrophotometer. For a better
repeatability of the spectrophotometric measurements, it is necessary to use an optical cell of long pathlength (8 cm or 10 cm). It is also required to control the temperature of the sample sea water in an opticalcell by circulating the temperature-controlled water in the cell-holder, and measure the temperature of
the sample at the time of spectrophotometric measurement by putting the temperature probe in the
optical cell in the position where the probe does not disturb the light path.
4-7 Thermostat bath

Thermostat bath is mounted with a circulation pump and capable of maintaining temperature at 25.0
±0.1°C. This is used to control the temperature of a sea water sample transferred for measurement andthat in an optical cell.
4-8 Thermometer

Calibrated thermometer is readable to 0.01°C. This is used to measure the solution temperature whentransferring from sampling bottle and to provide the value of solution temperature in optical cell for use
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in subsequent calculations.

5. Reagents/Supplies
5-1 Nitrogen gas

Stream of N 2 is supplied from a gas cylinder as described in 4-5 in order to remove CO 2 from thesea water sample that has been acidified with hydrochloric acid.
5-2 Deionized water

Beaker or optical cell is washed thoroughly with deionized water each time after the measurement
is finished.
5-3 Mixed titrant-indicator dye solution

A mixed solution of titrant and indicator dye of concentration approximately 0.05 mol dm-3 inhydrochloric acid (0.05 mol dm-3), 0.65 mol dm-3 in sodium chloride, and 80 ȝmol dm-3 in bromocresol
green is prepared in the following procedure.
5-3-1 InstrumentsyCalibrated balance to weigh 200g to within 0.01 mg.

yOven capable of drying reagents at 600°C.

y

Thermostat bath capable of controlling 25.0± 0.1°C and deep enough to immerse a 3 dm3volumetric flask to around its marked line.

5-3-2 Toolsy

1×3 dm3 borosilicate glass volumetric flask.

y

3×1 dm3 plastic screw-cap borosilicate glass bottle with Teflon-liner cap such as those of Schott
DuranR.

y

1×100 cm3 capacity porcelain crucible.

y

Desiccator with silica gel to store the porcelain cruicible.

y

1× a few cm3 capacity weighing bottle.

y

1×500 cm3 measuring cylinder.

y

1×300 cm3 capacity beaker.

5-3-3 ReagentsyHigh purity primary standard grade sodium chloride (>99.98%).

yHydrochloric acid (0.5 mol dm-3).

yBromocresol green sodium salt.

5-3-4 Procedures

In a day before:
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Put approximately 120g of sodium chloride in a porcelain crucible and dry it in an oven at 600°C
for > 1 hour. Allow to cool it in a desiccator over silica gel and put it near the balance.

yClean up and dry weighing bottle and beaker, and put them near the balance.
On the day of preparation:y

Weigh out 113.9180 g (1.95 mol) dried sodium chloride in a beaker.

yWeigh out 0.1818 g (240 ȝmol) bromocresol green sodium salt in a weighing bottle.

yPour 0.30 dm3 of 0.5 mol dm-3 hydrochloric acid (0.15 mol HCl) into measuring cylinder, andtransfer it thoroughly into a volumetric flask by rinsing with deionized water.

yUsing a funnel, transfer the weighed sodium chloride and bromocresol green to the volumetric flask.
Rinse the beaker and weighing bottle into the flask to ensure quantitative transfer of the sodium
chloride and bromocresol green salt into the flask.

yPour approximately 1 dm3 of deionized water into volumetric flask, shake it gently and let thesolutes dissolved.

yOnce sodium chloride was dissolved, pour deionized water up to below the calibration mark andshake the flask again to ensure a consistent composition.

y

Immerse the flask in the thermostat bath being controlled at 25.0± 0.1°C, and allow the temperatureof the mixed solution to reach an equilibrium value (> 20 minutes).

yAdjust the volume of solution contained in the flask to the calibration mark.

y

Once it is closed, shake the flask gently to mix the solution.

y

In case that the solution looks turbid because of the undissolved bromocresol green salts, filter out
the undissolved salts.

yFill 2×1 dm3 screw-cap bottles with the solution. Store the surplus solution in another screw-cap
bottle.

6. Procedures of the measurement
6-1 Outline

An analysis session, starting with clean up the burette, consists of the sequence of activities outlinedin Table 1. At each stage of this procedure, compare the results obtained with the system’s previous
history to ensure that the method is performing according to prescribed specifications. Once the initialtests are complete, water samples can be analyzed.

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Table 1. Recommended sequence of activities in an analysis session.
Activityy

Clean up the pipette and burette, and calibrate them. Clean up the optical cell.

y

Set the bottle of acid titrant and indicator dye mixed solution in place. Turn on the power ofthermostat bath, spectrophotometer, and so on. Wait until their performances get stabilized.

yRinse the burette and tubings with the acid titrant and indicator dye mixed solution.

yAnalyze two “junk” sea water samples to condition the system. Check the performance ofspectrophotometer and confirm no bubbles in acid titrant and indicator dye mixed solution
in the burette and tubings. If any problems are found, resolve it and analyze “junk” sea water
sample again.

yAnalyze sea water reference material.

yAnalyze sea water samples.

yAnalyze seawater reference material again.

yCalibrate the burette. Clean up the optical cell.

6-2 Clean up the optical cell

It is critical to keep the optical cell always clean. If it gets stained, small bubbles tend to attach on
the cell. They disturb precise spectrophotometric measurements and concurrently raise the baseline ofabsorbance. Optical cell is washed with brush and detergent but not with cleanser. Use of an ultrasoniccleaning machine is also recommended.
6-3 Clean up and calibrate pipette and burette

Volumetric pipette used to transfer sea water samples and volumetric burette used to deliver acid
titrant to sea water sample in beaker or in optical cell are required to be kept clean and calibrated. Before
and after a series of analysis, pre- and post-calibrations are required. In case that the apparatus is set on
board a ship, their delivery volume should be confirmed by collecting several replicate samples that canbe returned to the shore-based laboratory to be weighed. Deliver an aliquot of deionized water into a
pre-weighed serum bottle using the volumetric pipette and burette. Seal the bottle and save it to be
reweighed later (on return to shore).
The procedure has been described in Dickson, A.G., Sabine C. L., and Christian, J. R. (Eds.) 2007,“Guide to best practices for ocean CO 2 measurements. PICES Special Publication 3, 191 pp.”, chapter
4, SOP12 and SOP13 (http://cdiac.ornl.gov/oceans/Handbook_2007.html).
6-4 Analyze sea water reference material and sea water sample
6-4-1 Transfer sea water sample and measure absorbances of cell + sea water background

Transfer a sea water sample into the optical cell, and measure absorbances at 730 nm (baseline), at
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610 nm (maximum absorbance wavelength of base form of indicator dye (I2-)), and at 444 nm (maximum
absorbance wavelength of acid form of indicator dye (HI-)). They are the background absorbances ofthe sea water sample.
6-4-2 Dispense acid titrant and indicator dye mixed solution to the sample sea waterTransfer a known amount of sea water sample to a beaker or optical cell using a volumetric pipetteand measure the sample temperature. Dispense acid titrant and indicator dye to the sample. The volumeof acid titrant to be delivered is presumed from the site and depth of sampling and the salinity of thesample so that the pH of sea water sample becomes in the range between 3.8 - 4.2 after acid titrant is
added and the evolved CO 2 escapes from the solution. After dispensing the acid titrant and indicator
dye to the sample, stir the sample and aerate it with a stream of N 2 .
6-4-3 Measure absorbances of cell + sea water + dye

Measure absorbance at the same three wavelengths as those measured in 6-4-1. The same opticalcell as used to measure the background absorbances has to be used. Confirm that baseline absorbanceat 730 nm agrees with that in cell + sea water background measurement within ±0.01. In case that thedifference in the baseline exceeds 0.01, it is possible that small air bubbles attached on the cell anddisturbed the spectrophotometric measurement, and the measurement should be done again after the cellis cleaned.
6-4-4 Clean up the cell

Clean up the optical cell each time after the absorbance of the acidified sea water sample wasmeasured.
6-4-5 Remarks

Titrant acid in a screw-cap bottle should be replaced by another bottle of titrant acid when the headspace in the bottle exceeded half of the volume (500 cm3) since the concentration of hydrochloric acidis prone to change as the head-space increases. Once the acid titrant was replaced, substitute the titrant
that remains in the burette and tubings with the new one. It is also critical to ensure that there are no
bubbles in the burette and tubings.
It is desirable to repeat the measurement three times by changing the amount of acid titrant dispensed
to the sample at least for the reference material. In case that the measurements have been properly done
within the pH range of 3.8 – 4.2, the values of total alkalinity calculated will agree well irrespective of
the volume of acid titrant dispensed to the sea water sample.
6-5 Calculation of total alkalinity
6-5-1 Correction of absorbanceIf the spectrophotometer that outputs the light intensity is used, users need to calculate absorbance$Ȝ IURP WKH OLJKW LQWHQVLW\ DW HDFK RI WKHWKUHH ZDYHOHQJWKV IRU HDFK PHDVXUHPHQW EHIRUH DQG DIWHU
delivering acid titrant and indicator dye.

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G305EN-8

AȜ

§ I ·
 log10 ¨¨ ¸¸ 
© I0 ¹(3)

In the next, subtract the absorbances measured before adding acid and dye from that after. The
absorbance measured at a non-absorbing wavelength, i.e., 730 nm, is used to monitor and correct forany baseline shift. This assumes that the magnitude of any observed baseline shift is identical across thevisible spectrum. To do this, subtract the measured shift from the background - corrected absorbances
at wavelengths 610 nm and 444 nm to obtain the final corrected absorbance value at each wavelength.
These final absorbance values, corrected for background absorbances and any observed baseline
shifts, are used to calculate the absorbance ratio A 616 /A 444 that describes the extent of protonation of thedye.
6-5-2 Calculation of the pH of the sea water + acid + dye

The pH of the sea water + acid + dye in the cell is computed frompH·§
( A616 A444 ) 25  H 616 (HI  ) H 444 (HI  )¸
pK 2  log10 ¨¨

2
2
 ¸
H
H
A
A
H
H
(
I
)
(
HI
)
(
)
(
I
)
(
HI
)

444
616
444 25 444
444
© 616
¹

(4)

The equilibrium constant K 2 of the indicator dye bromocresol green at 25ºC is a function of salinity
and has been determined by careful laboratory measurements,
pK 2 = 4.2699 + (2.758×10-3)࣭(35 – S)

(5)

where S denotes salinity of the sample. A 616 and A 444 represent final corrected absorbance values at
616 nm and 444 nm, respectively, and (A 616 /A 444 ) 25 represents A 616 /A 444 ratio at sample temperature of
25ºC. (A 616 /A 444 ) 25 is calculated from Eq(6) using (A 616 /A 444 ) and sample temperature t (in ºC) in opticalcell when the spectrophotometric measurement is made.
(A 616 /A 444 ) 25  = (A 616 /A 444 ) [ 1 + 0.00907 (25 – t)](6)

7KH YDULRXV H[WLQFWLRQ FRHIILFLHQW WHUPV İ XVHG LQ (T 4) correspond to values measured for the
specified species at wavelengths 616 nm and 444 nm, respectively (Table 2).

Table 2. Extinction coefficient ratios for bromocresol green

İ 616 (HI-) /İ 444 (HI-)

0.00131-

İ 616 (I ) /İ 444 (HI )2.3148

İ 444 (I ) /İ 444 (HI )0.129922--

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6-5-3 Calculation of total alkalinity

Total alkalinity in sea water sample is calculated from Eq(2). The density of sea water is calculated
from salinity that has been measured separately and temperature of sea water sample when it istransferred from the sample bottle.
In case that the mercury chloride solution was added to the sample as a bactericide, further minor
corrections may need to be made to compute the total alkalinity in the original sea water sample:
A T = 1.0002 A T ’.

(7)

1.0002 is the coefficient when mercury chloride solution is added to the sample at the solution to
sample volume ratio of 0.02/100.
6-5-4 Confirmation of the procedureyIn case that the spectrophotometer outputs the light intensity, it is critical that the output at 444 nm
and 616 nm before and after acid – dye addition to the sea water sample is within the range that theoutput changes linearly with the change in the light intensity.

ypH of sea water sample is within the rage of 3.8 – 4.2 when the spectrophotometric measurements
is made after acid is added and CO 2 is removed.

yAbsorbance at 730nm before and after the addition of acid and dye to a sea water sample should
agree within ± 0.01.
If any of these conditions have not been satisfied, problems have to be found and resolved, and themeasurement has to be done again for the same sample. In principle, increase in the headspace air in thesampling bottle will not effect on the value of total alkalinity in sea water sample. Therefore,
measurement of total alkalinity in a single bottle can be repeated if enough sea water sample to transfer
to beaker or optical cell by volumetric pipette remains in the bottle.
7. Analysis of reference material
It is necessary that concentration of hydrochloric acid used to determine total alkalinity as a titrant
has been calibrated within the uncertainty of ±0.02%. However, in case that such an accurate calibration
is not possible on board a ship or in a laboratory on land, circumstances may force one to use theCertified Reference Material (CRM) for dissolved inorganic carbon and total alkalinity analyses
provided by Dr. A. G. Dickson in Scripps Institute of Oceanography to determine the concentration of
the hydrochloric acid.
7-1 Procedure

Determine total alkalinity of the CRM according to the procedure described in 6.4. In order toevaluate the uncertainty due to the non-linearity in the response of spectrophotometer and due to theerror in the volume of acid dispensed from a burette and so on, measurements should be repeated threetimes while changing the volume of acid titrant dispensed to the sample but keeping its resultant pH fallwithin the range of 3.8 – 4.2.
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7-2 Calculation of the concentration of hydrochloric acidCalculate the concentration of hydrochloric acid in the titrant:

cHCl{ AT CRM  VCRM  [H  ]T  (VCRM  VHCl )}  U CRM(8)VHCl  106

A T CRM represents the certified value of total alkalinity in the CRM. V CRM represents the volume of
CRM used for the analysis. The same volumetric pipette as that used for the sea water sample should be
used so that V CRM and V SW in Eq(2) become identical. ȡ SW is calculated from the salinity of the CRM
that has been determined and the temperature of the CRM when it is transferred from the bottle using
the volumetric pipette.
8. Example calculations
8-1 Determination of the concentration of hydrochloric acid in titrant using CRM

Certified value of total alkalinity in CRM A T CRM

2224.65 ȝmol kg-1

Salinity of CRM

33.357

Volume of pipette V CRM

42.7495 cm-3

Volume of acid titrant added to the sample

2.05 cm3

Measured data:
25.14 °C, 1.0221 g cm-3

Temperature and density of CRM

Temperature of the sample at the time of spectrophotometric measurement25.32° C

Measured light intensity and absorbance:
Wavelength

Sea water

Dye + acid + sea water

Reference

SampleReference

444 nm

25827

21890

18305

21863

0.1490616 nm

36417

38894

27596

38868

0.1202730 nm

13883

12699

13816

12679

0.0014

Result଴.ଵଶ଴ଶି଴.଴଴ଵସ

A 616 /A 414=(A 616 /A 414 ) 25

0.8026

pH T

3.8483଴.ଵସଽ଴ି଴.଴଴ଵସ

= 0.8050[H ] T

141.8 ȝmol kg-1

 c HCl

0.050577 mol dm-3+

AbsorbanceSampleGuideline of ocean observations Vol. 3 Chap. 5
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8-2 Total alkalinity in sea water sample

Salinity of sea water sample

34.424

Volume of pipette V SW

42.7495 cm3Concentration of hydrochloric acid c HCl

0.050577 mol dm-3

Volume of acid titrant added to the sample

2.15 cm3

Measured data
25.22 °C, 1.0228 g cm-3

Temperature and density of sea water sample

Temperature of the sample at the time of spectrophotometric measurement

25.73° C

Measured light intensity and absorbance:
Sea water

Wavelength

Dye + acid + sea water

AbsorbanceSampleReference

SampleReference

444 nm

25876

21904

18460

21891

0.1464616 nm

36542

38921

25615

38912

0.1542730 nm

13936

12734

13873

12736

0.0020Results
଴.ଵହସଶି଴.଴଴ଶ଴

A 616 /A 414=(A 616 /A 414 ) 25

1.0470pH T

3.9678଴.ଵସ଺ସି଴.଴଴ଶ଴

= 1.0540[H ] T

107.7 ȝmol kg-1

AT

2373.8 ȝmol kg-1+

9. Quality assurance
9-1 Quality of each titration data

In order to assure the data quality of each sample, absorbance (light intensity), pH after adding acidto sample, and change in the baseline of spectrum (730nm) before and after the addition of acid and dyeneed to be controlled. Repeatability of analysis should be also evaluated by making replicate analyses
by adding a constant volume and different volumes of acid titrant to the same sea water sample.
9-2 Analysis of reference material

A stable reference material should be analyzed regularly. Plot the results on a property control chart.
9-3 Duplicate analyses

A duplicate analysis should be made regularly on sea water sample and sea water reference material
by adding a constant volume and different volumes of acid titrant. Plot the difference between each pairof analyses on a range control chart. The standard deviation expected is within 2 Pmol kg-soln-1.
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Reference
Breland II, J. A. and R. H. Byrne, 1993. Spectrophotometric procedures for determination of sea water alkalinity
using bromocresol green. Deep-Sea Res. I, 40, 629–641.
Dickson, A.G. 1981. An exact definition of total alkalinity and a procedure for the estimation of alkalinity andtotal inorganic carbon from titration data. Deep-Sea Res. 28A: 609–623.
Dickson, A.G., Afghan, J.D. and Anderson, G.C. 2003. Reference materials for oceanic CO 2 analysis: a method
for the certification of total alkalinity. Mar. Chem. 80: 185–197.
Yao, W., and Byrne, R. H. 1998. Simplified seawater alkalinity analysis - application to the potentiometrictitration of the total alkalinity and carbonate content in sea water, Deep-Sea Res. I, 45: 1383-1392.

Acknowledgment
We have prepared this guidline by referring to and in a similar format to Dickson, A.G., Sabine, C.L.
and Christian, J.R. (Eds.) 2007, “Guide to best practices for ocean CO 2 measurements”. PICES Special
Publication 3, 191 pp.

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pH
A Standard Operation Protocol of “Determination of the pH of sea water” is available from thefollowing CDIAC web site:
http://cdiac.ornl.gov/ftp/oceans/Handbook_2007/sop06a.pdf
http://cdiac.ornl.gov/ftp/oceans/Handbook_2007/sop06b.pdf
http://cdiac.ornl.gov/oceans/Handbook_2007.html

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pCO2
A Standard Operation Protocol of “Determination of p(CO2) in air that is in equilibrium with adiscrete sample of sea water” is available from the following CDIAC web site:
http://cdiac.ornl.gov/ftp/oceans/Handbook_2007/sop04.pdf
http://cdiac.ornl.gov/oceans/Handbook_2007.html

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Chlorofluorocarbons and sulfur hexafluoride
A standard method of “sampling and measurement of chlorofluorocarbon and sulfur hexafluoride inseawater” is available from the following GO-SHIP repeat hydrography manual web site:
https://www.go-ship.org/Manual/Bullister_Tanhua_CFCSF6.pdf

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Carbon isotopic ratios (Δ14C, δ13C) of dissolved inorganic carbon
Yuichiro KUMAMOTO (Japan Agency for Marine-Earth Science and Technology),
Takafumi ARAMAKI (National Institute for Environmental Studies)

1.

Introduction
There are three isotopes of carbon, 12C, 13C, and 14C in the environment and the abundance

ratios of 13C and 14C to 12C are about 10–2 and 10–12, respectively. Both 12C and 13C are stable
isotopes while 14C is a radionuclide (radiocarbon) with a half-life of about 5730 years that isnaturally derived from the reaction of atmospheric nitrogen and cosmic rays in the atmosphere.
The 13C/12C and 14C/12C ratios vary due to the isotopic fractionation in the environment. Unlike
the 13C/12C ratio, the 14C/12C ratio decreases with time due to the radioactive decay. In addition,
the 13C/12C and 14C/12C ratios have been disturbed by the fossil fuel combustion and utilization of
nuclear energy and weapons by humans, respectively. Thereby, the two isotopic ratios of dissolved
inorganic carbon (DIC), which is the sum of carbonate ion, bicarbonate ion, and molecular carbon
dioxide (CO2), in seawater are useful indicators for studies on the gas exchange at sea surface,marine carbon cycle, and the ocean circulation.
The high-precision measurement of the stable carbon isotopic ratio, 13C/12C was achieved by astable isotope ratio mass spectrometer (SIRMS) equipped with a dual-inlet device (McKinney etal., 1950). To measure the 13C/12C of DIC in seawater by a SIRMS, DIC in seawater is stripped as
CO2 gas. In recent years, continuous measurements of the 13C/12C of DIC in surface seawaterusing a SIRMS or cavity-ringdown spectrometer, which is equipped with a pretreatment device
for CO2 extraction and purification, have been reported (e.g. Oguma et al., 2012; Becker et al.,2012). Since the 14C/12C ratio varies with the two factors: the isotopic fractionation and radioactive
decay, the correction for the isotopic fractionation using the 13C/12C ratio is necessary to estimate
the effect of the radioactive decay on the 14C/12C ratio. Therefore, the two isotopic ratios of DIC
are usually measured together. In this chapter, we describe analytical methods for thesimultaneous measurements of the 13C/12C and 14C/12C ratios in CO2 gas extracted from a seawater
sample.
In the late 1940s, the natural 14C derived from the cosmic rays was discovered and theradiocarbon dating for a time range of 103 to 104 years was proposed (Anderson et al., 1947; Libby
et al., 1949). The 14C has been measured by the analysis of its radioactivity, in which beta rays
emitted by the radioactive decay of 14C are measured using a gas proportional or liquid
scintillation counting device. The measurement of 14C of DIC in seawater samples started in the
1950's (e.g., Linick et al., 1978). In the early stage, observational data from deep layers werelimited, because the radioactivity analysis of 14C needs a few hundred liters of seawater. In the
Geochemical Ocean Section Study (GEOSECS) conducted by oceanographers of the United
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States in the 1970s, 250 L of seawater was collected at 18 layers from the surface to bottom at
125 stations using a large-volume water sampler. The DIC in the sample was stripped as CO2 gas
and absorbed in sodium hydroxide solution on board. After the conversion from the recovered
CO2 gas to acetylene gas in an onshore laboratory, radiocarbon in the gas sample was measured
using gas proportional counters (Stuiver and Östlund 1980; Östlund and Stuiver, 1980; Stuiverand Östlund, 1983). In Japan, in addition to the acetylene method (Gamo and Horibe, 1983),
radiocarbon has been measured by the liquid scintillation since the 1980s, in which benzene
synthesized from acetylene is dissolved in organic solvent (Tsunogai et al., 1995).
The accelerator mass spectrometer (AMS) developed in the late 1970s (Muller, 1977; Purser,1977) can measure 14C with a sample amount of 1/1000 or less as compared to that for theradioactivity measurement because 14C atoms are determined directly in the AMS method. As thesmaller AMS with low acceleration voltage (2–3 MV) was newly developed in the early 1990s,
the AMS has been widely used in the oceanography. In the World Ocean Circulation Experiment(WOCE) conducted in the world ocean in the 1990's, more than 15,000 of seawater samples (500mL or less) were collected at 785 stations and 14C of DIC was measured by the AMS method (Keyet al., 2004). Because the analytical sensitivity of the AMS method is high, it is possible to obtaina measurement result with an uncertainty of about 0.5% by the AMS measurement with a carbon
content of 1 mg for 30 minutes. As a result, most of the 14C measurements are conducted using
the AMS method these days.
A manual on the radiocarbon measurement by the AMS method, which was prepared for the
WOCE, has been widely used (McNichol and Jones, 1992). The manual was revised in 2010
(McNichol et al., 2010), but there is no major change in it. In Japan, Aramaki (1999) reported
methods for the seawater sample pretreatment and 14C measurement at the AMS facility of theJapan Atomic Energy Research Institute (the Japan Atomic Energy Agency since 2005). In thesemanuals, methods of water sampling on shipboard and sample pretreatment were mainly
described, and there is not much description about the sample analysis using the AMS. In thischapter, we describe the water sampling, sample pretreatment, and analytical method along theorder of the actual procedures, so that the readers can overview all the analytical procedures of
the carbon isotopic ratios of DIC in the seawater sample. The definition and unit (2), sampling(3), sample pretreatment (4, 5), and analyses (6) are described in the following sections.
2.

Definition and unit

2-1. δ13C
The difference in the 13C/12C ratio between the sample (RSA) and standard material (RST) isexpressed as a permillage (δ13C [‰]).
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δ13C = (RSA / RST – 1) × 1000

(1)

Belemnites fossils from the Pee Dee Formation in North Carolina, the USA (PDB), is the primary
standard material of the 13C/12C ratio. δ13C should be written as δ13CPDB precisely. However, thedemand for the PDB exhausted the supply and secondary standards calibrated to the PDB are
distributed by the International Atomic Energy Agency (IAEA) in Vienna, Austria. The value ofδ13C relative to the secondary standard (Vienna PDB) is expressed as δ13CVPDB.
2-2. Δ14C
As with the 13C/12C ratio, the difference in the 14C/12C ratio between the sample (ASA) andstandard material (AST) is expressed as a permillage (δ14C [‰]).
δ14C = (ASA / AST – 1) × 1000

(2)

The primary standard material of the 14C/12C ratio is wood in the 19th century (AD 1890), whose
14

C/12C ratio was not disturbed by human activities. However, it is practically impossible to obtainsuch wood. Therefore, oxalic acid supplied by the National Institute of Standards and Technology(NIST), SRM 4990 (Oxalic Acid I) and SRM 4990C (Oxalic Acid II) have been widely used as
the standard materials. The measured 14C/12C ratio of the oxalic acid (AOX) is converted into thatof the standard wood (AON = AST) in modern times by the following approximate expression(Karlén et al, 1966).
AON = 0.95 AOX [1 – {2 (19 + δ13CPDB) / 1000}](3)

where δ13CPDB is the δ13C value of Oxalic Acid I. The equation 3 corrects the difference in theisotopic fractionation effect between the oxalic acid and wood, and indicates that the isotopic
fractionation effect on the 14C/12C ratio is approximately twice that of the 13C/12C ratio. Strictly,
the isotopic fractionation effect can be obtained by the following equation.
AON = 0.95 AOX (1 – 19/1000)2 / (1 + δ13CPDB/1000)2(4)

Because the δ13C of Oxalic Acid I is –19.3 ‰, the difference in results from the equations 3 and4 is negligibly small (< 0.001%).
Oxalic Acid I is no longer commercially available at present. Thus, Oxalic Acid II is the current
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standard material, whose 14C/12C ratio (ANOX) is converted into that of the standard wood (AON =AST) in modern times by the following approximate expression (Stuiver, 1983).
AON = 0.7459 ANOX [1 – {2 (25 + δ13CVPDB) / 1000}](5)

where δ13CVPDB is the δ13C value of Oxalic Acid II. The isotopic fractionation effect can be
precisely calculated by the following equation. However, the difference in results from theequations 5 and 6 is negligibly small (< 0.02%) because the δ13C of Oxalic Acid II is –17.8 ‰,AON = 0.7459 ANOX (1 – 25/1000)2 / (1 + δ13CVPDB/1000)2(6)

Because radiocarbon in the oxalic acid declines by the radioactive decay, the 14C/12C ratio of
the standard material (AON) decreases with time. The AON decay-corrected to AD 1950 is called
as the absolute 14C/12C ratio of the standard material (AABS) (Stuiver & Polach, 1977).
AABS = AON eλ(y - 1950)(7)

where y is the measurement year, and λ is the radioactive decay constant of 14C (1/8267 yr–1).
Finally, δ14C is calculated by substituting AABS for AST in the equation 2.
δ14C = (ASA / AABS – 1) × 1000

(8)

δ13C of wood (the primary standard material) is about –25 ‰. On the other hand, δ13C of marineorganic matter and DIC in seawater are about –15 ‰ and 0 ‰, respectively. Therefore, δ14C insamples with different δ13C values cannot be compared directly. For geochemical samples
including seawater, Δ14C [‰] is used instead of δ14C.
∆14C = (ASN / AABS – 1) × 1000

(9)where ASN is the corrected ASA (the 14C/12C ratio of the sample) using the δ13C value of the sample(δ13CVPDB) as follows.
ASN = ASA [1 – {2 (25 + δ13CVPDB) / 1000}](10)ASN = ASA (1 – 25/1000)2 / (1 + δ13CVPDB/1000)2

(11)

or

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The equation 10 is the approximate expression of the equation 11, and the range of δ13CVPDB from–30 ‰ to 5 ‰ corresponds to the difference between them from 0.02% to –0.13%. The value of
Δ14C is identical to the δ14C in the sample that would have the same δ13C as that of wood (–25 ‰).
The difference between δ14C and Δ14C of DIC is about 50 ‰. In addition, if the sampling year (z)and the measurement year (y) are different, ASA in the equation 8 for δ14C and ASN in the equation
9 for Δ14C should be replaced by ASA·eλ (y–z) and ASN·eλ (y–z), respectively.
In the radiocarbon dating for archaeological samples, the AABS in the equations 8 and 9 is
replaced by AON because the radioactive decay in the sample and standard cancel each other(Stuiver and Polach, 1977).
d14C = (ASA / AON – 1) × 1000

(12)D C = (ASN / AON – 1) × 1000

(13)

14

Although d14C [‰] and D14C [‰] are confusable with δ14C and Δ14C, they should be distinguishedstrictly. The ASN/AON and ASN/AABS ratios in a percentage are called the percent modern carbon(pMC) and absolute pMC, respectively. The notation for the radiocarbon measurement describedin this section follows those in Stuiver and Polach (1977), which has not been displaced yet by a
new less-confused notation proposed by Mook and van der Plicht (1999).
3.

Sampling
As stated in the section 1, the method for the simultaneous measurements of 13C and 14C of DIC

in seawater is described. The sampling (3) and CO2 gas stripping (4) are common to both of themeasurements.
3-1. Apparatus and reagents
3-1-1. Sample bottle
To prevent contamination from atmospheric CO2 gas, use a glass bottle of 250 ml (or 500 ml)
nominal volume and a ground glass stopper with grease. The weights of carbon necessary for the
14

C and 13C measurements are approximate 1 mg (= about 100 μmol) and 0.1 mg (= about 10μmol), respectively. The required volume of the seawater sample is 100 ml because the DIC
concentration in seawater is about 2000 μmol·L-1. After use, wipe the grease on the bottle/stoppers
with acetone, soak in alkaline detergent and 10% hydrochloric acid subsequently, and wash withpure water. Then bake them in an electric furnace at 450 °C overnight and let them cool. Finally,each bottle/stopper pair is numbered and weighed (tare measurement).

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3-1-2. Grease
Apiezon greases L, M, N are recommended. Transfer grease into a plastic syringe with a 10 mL
volume for easier handling.
3-1-3. Mercury chloride (II) saturated solution
Approximately 10 g of special-grade mercuric chloride (II) powder is added to about 100 mLof pure water in a plastic bottle and dissolved. Because the solubility of mercuric chloride (II) at
room temperature is about 7 g/100 mL, the powder remains in the bottom of the bottle. The
solution and waste with mercury chloride (II) must be handled with care because mercury chloride(II) is very toxic.
3-1-4. Pipettes
Prepare a micro pipette for dispensing 50 μL of the saturated solution of mercuric chloride (II)into seawater samples. Another pipette with 10-mL volume is also necessary to pour off theseawater sample in the bottle for making a headspace (3-2-2).
3-2. Water sampling
3-2-1. Water drawing
The method of the seawater drawing from a water sampler into the sample bottle is inaccordance with the sampling method for DIC analysis (Dickson et al., 2007). The seawater
sample for the carbon isotopes measurement is usually drawn just after the seawater sampling forDIC.
3-2-2. Poisoning
The seawater sample in the bottle must be poisoned with mercuric chloride (II) as soon as
possible to prevent the change in DIC concentration due to biological activity, which is called the"fixation" of the sample. Remove the stopper from the bottle and wipe off the seawater on the
stopper using a piece of paper. Pour off the seawater in the bottle using the 10-ml pipette (3-1-4)
and wipe off the seawater on the inside wall of the bottle neck. Then, 50 μL of the saturated
solution of mercuric chloride (II) is added to the seawater sample using the micro pipette (3-1-4).
Apply an appropriate amount of the grease to the ground glass joint of the stopper, return it to thebottle, and twist it around while applying pressure to ensure that a good seal is made. If the amountof the grease is insufficient, the grease seal does not work while the excess amount of the grease
could result in a drop of the grease into the bottle, which causes stains on an air bubbler (4-5). Fix
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the stopper to the bottle tightly using a clip or rubber bands. Store the seawater sample in a cooland dark place until pretreatment.
4.

Pretreatment I (CO2 stripping)
To measure the carbon isotopic ratios of DIC, DIC should be stripped from the seawater sample

as CO2 gas. There are a few methods for the stripping. In the precipitation method (Drimmie etal., 1991), DIC is precipitated as strontium carbonate or barium carbonate and then CO2 gas isrecovered by soaking the precipitates into acid solution. In the headspace method (Ishii et al.,
2000; Salata et al., 2000), CO2 in a headspace in a closed bottle, which degassed from acidified
seawater in the bottle, is recovered. In the bubbling method (McNichol and Jones, 1992), acid is
added to the seawater sample to reduce the solubility of CO2 and then the CO2 is stripped fromthe seawater by bubbling of an inert gas such as pure N2. The bubbling method is most popularamong them for seawater samples (McNichol et al., 2010). In this section, we describe a bubbling
method using a vacuum device for the stripping and purification of CO2 gas currently conductedin the National Institute for Environmental Studies (NIES), in which all the procedures proceedmanually. However, semi-automated devices have also been reported (Aramaki et al., 2000;
Honda et al., 1999; McNichol and Jones, 1992).

Fig. 1A schematic view of the vacuum device for the CO2 stripping.

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4-1. Vacuum device for stripping
Fig. 1 is a schematic view of the vacuum device for the CO2 stripping installed in NIES. Mostof the parts of this vacuum device (< 0.1 Pa vacuum degree) is made of borosilicate glass except
for some metal or resin parts (e.g. valves and joints). Because the borosilicate is easily-worked, it
is possible to reduce uses of joints that may cause leakage. Grease-less stop valves arerecommended for keeping low vacuum degree. In recent years, the vacuum device composed bystainless steel pipes and joints are also used widely.
4-2. Stripping probe
Weigh the seawater sample bottle andcalculate the weight of the seawater sample
by subtracting the tare weight (3-1-1) fromthe bottle weight. A stripping probe (Fig. 2)
is placed on the seawater sample bottle in a
N2-filled glove bag or box. Prior to that, 4mL of 85% phosphoric acid (H3PO4)
solution is set in the stripping probe. Afterconfirming that the three vacuum valves ofthe probe are closed, the sample bottle +stripping probe is connected to the vacuum

Fig. 2 The sample bottle + the stripping probe.

device using a joint (Fig. 1).
4-3. Nitrogen gas filling
The air in the vacuum device is exhausted and then filled with pure N2 gas (>99.9999%) to apressure of about 1.2 atm using a pressure gauge. The N2 gas in the circulation flow path (a shaded
area in Fig. 1) is isolated by closing the valves. The three vacuum valves of the stripping proberemain closed.
4-4. Injection of phosphoric acid
Open the vacuum valve of the stripping probe above the phosphoric acid solution, and thesolution is poured into the sample bottle by the pressure difference between the vacuum device(1.2 atm) and sample bottle (1 atm). pH of the seawater sample drops and the DIC in the sample
changes to gaseous CO2.

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4-5. Stripping
After the phosphoric acid solution is dropped into the sample bottle, close the vacuum valve
for the acid solution and open the two others of the stripping probe, and turn on the circulation
pump. The N2 gas in the circulation flow path starts to circulate, and air bubbles are released fromthe bubbler inserted in the sample bottle (Fig. 1). The flow rate of the N2 circulation is 0.5 to 1.0
liter/min. It takes about 10 minutes for the CO2 stripping from 250 ml of the seawater sample.
Prior to the sample stripping, it is necessary to estimate the proper flow rate and time to obtain
more than 95% of CO2 recovery (4-6). During the recirculation of the N2 gas, the cold traps forCO2 (T1 and T2) and water (T3) should be cooled to –196°C by liquid nitrogen and –72°C by ice
slush of dry ice/ethanol, respectively. After the stripping is complete, turn off the circulation pump,isolate the water trap (T3) and the stripping probe/sample bottle by closing the valves, and thenexhaust the N2 gas in the vacuum device using the vacuum pump.
4-6. Recovery
The extracted CO2 in the traps T1 and T2 is purified by changing the cryogen from the liquid
nitrogen to the ice slush. Then only the gaseous CO2 is transferred to the tube for CO2 volume
measurement (cold finger) just under the pressure gauge (Fig. 1) using liquid nitrogen. The
volume of the section with the cold finger and pressure gauge isolated by the two valves must be
measured in advance, using a tube with a grease-less valve whose inner volume is determined bya gravimetric calibration using mercury or water. Then, remove the liquid nitrogen from the cold
finger and measured the pressure of the CO2 gas filled in the isolated section at room temperatureusing the pressure gauge. The amount (mol) of the CO2 recovered is calculated by the pressure,
the room temperature, and the volume of the isolated section with the cold finger. Meanwhile, theamount of CO2 (mol) contained in the seawater sample is calculated from the DIC concentrationand the weight of the seawater sample (4-2). Then, calculate the recovery rate from the amountsof CO2 recovered from and contained in the seawater. To prevent the isotopic fractionation effectduring the CO2 stripping, this recovery rate should be larger than 95% (McNichol and Jones,
1992).
4-7. Storage
The recovered CO2 gas is split into two subsamples as follows. The CO2 gas is transferred to
the glass tube for 14C from the isolated section with the cold finger using liquid nitrogen and close
the valves A and B (the valve C remains open) (Fig. 1). Then the liquid nitrogen is removed, andthe CO2 gas spreads in the small section isolated by the valves A and B. After a brief interval for
the CO2 gas diffusion, the valve C is closed. Then, the CO2 gas below the valve C is condensed
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cryogenically and sealed in the glass tube for 13C using a gas torch. Meanwhile, the CO2 gas thatremains in the section isolated by the valves A, B, and C is also condensed and sealed in the glass
tube for 14C. If the interval for the CO2 gas diffusion is insufficient, the isotopic fractionation
between the CO2 gas for 14C and 13C may occur. In the NIES vacuum device (Fig. 1), the interval
time for the gas diffusion was empirically estimated to be more than 5 minutes. It is necessary toestimate the proper interval time in advance for each vacuum device. The split ratio of the CO2gases for 14C and 13C is about 4:1 in the NIES vacuum device, suggesting that the amount of theCO2 gases for 14C and 13C are about 400 and 100 μmol, respectively. The CO2 gas sealed in theglass tubes are semi-permanently stable. The CO2 gases for 14C and 13C are converted to graphite
powder for the AMS measurement (5) and analyzed by the SIRMS (6-1), respectively.
5.

Pretreatment II (graphitization)
To measure radiocarbon using the AMS, the CO2 gas extracted from the seawater sample has

to be reduced to solid carbon. A few methods for the CO2 reduction were proposed. CO2 gas canbe reduced to amorphous carbon using magnesium (Yoshikawa et al., 1987). The amorphous
carbon, however, has no electric conductivity that is required for the AMS measurement. CO2 gas
can also be reduced to graphite carbon, which has electric conductivity unlike amorphous carbon,
using metallic lithium and electrodeposits (Gurfinkel, 1987) or iron powder and hydrogen gas

Fig. 3 A schematic view of the vacuum device for the graphitization.
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G309EN-11(Vogel et al., 1984). The graphitization with hydrogen is the simplest and yields the highest
recovery rate among the three methods. In this section, we describe a graphitization method
currently conducted in NIES, which was modified by Kitagawa et al. (1993).
5-1. Vacuum device for graphitization
Fig. 3 is a schematic view of the vacuum device for the graphitization of CO2 gas in NIES. As
with the vacuum device for the CO2 stripping (4), most of the parts of this device are made ofborosilicate glass.
5-2. Iron powder (catalyst)
Prepare pure iron powder used as a catalyst for the CO2 reduction reaction. The particle size
should be as fine as possible, and we use that with a particle size of 10 μm or less. The iron powdercommercially available may be contaminated with organic matter or oxidized slightly. Therefore,
it is recommended that the iron powder is heated at 650 °C for 1 hour with hydrogen gas before
use to decompose the organic matter and reduce the iron oxide. The procedures of this pre-heatingof the iron powder are in accordance with those in the sections 5-5 and 5-6 without the sample
CO2 gas.
5-3. Graphite reactor
The weight of the iron powder (mg) should be equal to that of the graphite powder produced
from the CO2 gas (Kitagawa et al., 1993). When the graphite powder is less than 1 mg, therecovery rate of graphite is improved by doubling the amount of the iron powder. Measure thetare weight of a small quartz tube with a length of about 2 cm and an outer diameter of 6 mm (4mm inner diameter) and weigh the iron powder in the quartz tube. Transfer the small quartz tube
with the iron powder gently into a quartz tube
with a length of about 20 cm and an outer
diameter of 9 mm (“reduction tube” in Fig.
3). Quartz is available in an electric furnace
at 650 °C (5-6). The reduction tube is
attached to a tube with a grease-less valve,
which is called the graphite reactor (Fig. 4).
The approximate inner volume of thegraphite reactor must be estimated in advancefor the determination of H2 pressure injected
into the reactor (5-5). Then the graphite

Fig. 4 The graphite reactor.

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reactor is connected to the vacuum device using a joint and the air in it is exhausted using thevacuum pump.
5-4. Transfer of CO2 gas
The glass tube in which the sample CO2 gas for 14C measurement is sealed (4-7) is set in a
glass-tube cracker, or a sample cracker (Fig. 5). Then the sample cracker with the sample glass
tube is connected to the vacuum device using a joint and the air in it is exhausted. The glass tube
is broken by screwing a rod attached to the cracker (Fig. 5) and the sample CO2 gas is transferred
into the vacuum device and condensed in the T1 trap (Fig. 3) cooled to –196 °C using liquid
nitrogen. The condensed CO2 in the T1 trap is purified by changing the cryogen from liquid
nitrogen to the dry ice/ethanol slush. Then
only the gaseous CO2 is transferred to thetube for CO2 volume measurement (coldfinger) just under the pressure gauge (Fig. 3)
using liquid nitrogen. As with the vacuum
device for the CO2 stripping (4-6), thevolume of the small section with the cold
finger and pressure gauge isolated by the twovalves must be measured in advance.
Remove liquid nitrogen from the cold finger
and measured the pressure of the CO2 gas

Fig. 5 The sample cracker..

filled in the isolated section at room temperature using the pressure gauge. The CO2 amount (mol)is calculated from the pressure, the room temperature, and the volume of the isolated section.
5-5. Injection of hydrogen gas
Graphite powder (C) is generated from CO2 gas and hydrogen (H2).
CO2 + 2H2→

C + 2H2O(14)

To reduce the CO2 gas to the graphite powder completely, the amount (mol) of the hydrogen gas
should be the double of that of the sample CO2 gas, which is calculated from the inner volume of
the graphite reactor (5-3) and H2 pressure in it. The recovery rate of the graphite powder isimproved by using 2.1–2.2 times the amount of the hydrogen gas (Kitagawa et al., 1993). Aftercondensation of the CO2 gas in the graphite reactor using liquid nitrogen, pure H2 gas(>99.9999%) is injected into the vacuum device. Although the graphite reactor is cooled to
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G309EN-13–196 °C to retain the sample CO2 in it, the injected H2 gas is not trapped in the graphite reactor.
Adjust the pressure of the H2 gas using the pressure gauge. Close the valve of the graphite reactor
and remove liquid nitrogen from it. The inner volume of the graphite reactor should be determinedby the total pressure of the sample CO2 and H2 in it at room temperature. If the total pressure ishigher than 1.5 atm, the sealing of the graphite reactor may be broken.
5-6. Graphitization
Remove the graphite reactor from the vacuum device and insert the quartz tube of the graphite
reactor into a hole (about 10 mm diameter) of an electric furnace heated at 650 °C for about 6 to
12 hours to reduce the sample CO2 gas to the graphite powder on the iron powder. Water droplets
derived from the reduction reaction (the equation 14) appear on the inner wall of the L-shapedpart of the graphite reactor (Fig. 4). A cooling of the L-shaped part using a Peltier cooler or anothercryogen facilitates the reaction (Aramaki, 1999). The L-shape part prevents a back slip of thewater droplets into the quartz tube after the cease of the heating.
5-7. Weighing of graphite
Weigh the small quartz tube with the recovered graphite and iron powder. Calculate the weightof the graphite by subtracting the weight of the quartz tube and the iron (5-3) from the total weight.
The graphitization recovery is estimated from the amounts of the graphite and the CO2 used forthe graphitization (5-4) and ranges normally between 70% and 90%. When the recovery is lessthan 60%, the isotope fractionation may occur in the process of the graphitization (Kitagawa etal., 1993).
6.

Analyses

6-1. δ13C
6-1-1. Standard gas
Prepare the CO2 gas with a known δ13C value, namely the standard gas to measure δ13C using
the dual inlet SIRMS. The standard substance of calcium carbonate supplied by IAEA (2-1). The
method for the recovering CO2 gas from the standard calcium carbonate was described by
Verkouteren and Klinedinst (2004). Otherwise, the commercial products of the standard CO2 gas
with a known δ13CVPDB value are available (e.g., Oztech Trading Corporation).

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6-1-2. Injection of sample gas
Connect a container containing the standard CO2 gas to the standard inlet of the SIRMS.
Meanwhile, the glass-tube cracker (5-4) with the sample glass tube for 13C measurement (4-7) isconnected to the sample inlet, which allows injecting the sample CO2 gas into the SIRMS. An
automatic sample cracker for the sample glass tube is equipped with the SIRMS as an option.
When you use the manual tube cracker for the injection of the sample CO2, it is necessary to takesufficient time for the gas diffusion so as not to cause the isotopic fractionation.
6-1-3. δ13C determination and uncertainty
The sample and standard CO2 gases are measured sequentially several times automatically by
a computer program. The δ13C value of the standard CO2 gas should be input into the program in
advance. The program outputs an average δ13C value and its standard deviation for the several
repeat measurements. This standard deviation, however, indicates only the uncertainty of therepeat measurement of the same sample gas. The standard deviation in the replicate measurementof the same seawater sample is estimated to be about 0.03 ‰ (McNichol et al., 2010), which
includes the uncertainty derived from not only the SIRMS analysis but also the sampling andsample pretreatment.
6-2. Δ14C
The AMS consists of the ion source, accelerator, mass spectrometry systems, electromagnets,
and detectors (Fig. 6). There are several models of the AMS. Here, we describe the AMS system

Fig. 6

A schematic view of the tandetron tandem accelerator.

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manufactured by High Voltage Engineering Europe, Netherlands, called the tandetron tandem
accelerator. This model has been installed at Nagoya University and Japan Atomic Energy Agency
in Japan.
6-2-1. Standard
As with the 13C measurement by the SIRMS, the AMS measures 14C in the sample and standard
sequentially. Procedures of a combustion method for the graphitization of the NIST Oxalic Acid
II (2-2) are as follows. Pack about 5 mg of the oxalic acid, which corresponds to about 1 mg ofgraphite, and about 1 g of copper oxide into a borosilicate glass tube with a length of about 7 cm
and an outer diameter of 6 mm (4 mm inner diameter). Then insert it in a borosilicate glass tube
with a length of about 30 cm and an outer diameter of 9 mm (7 mm inner diameter) together with
about 0.5 g of reduced copper and about 1 mg of a silver piece. Silver prevents generation ofinterfering gas during the combustion. After the exhausting of the air in the glass tube using avacuum pump, seal the upper part of the glass tube with a gas torch. The sealing can be conductedusing the vacuum device for the stripping or graphitization. Heat the sealed tube in an electric
furnace at 550 °C for 8 hours. The metallic luster of the reduced copper in the glass tube is theindicator for the successful combustion of the oxalic acid. After cooling the glass tube to room
temperature, purify and graphitize the CO2 gas in the tube according to the procedures in thesection 5. The graphitization of the standard CO2 gas must be conducted using the same vacuum
device as that for the sample CO2 graphitization. For the quality control of the AMS results, it isrecommended to measure the reference materials supplied by IAEA (e.g., IAEA-C7 Oxalic Acid,
pMC = 49.53%) together with the sample and standard graphite powders. In addition, results ofthe standard graphite newly prepared should be compared with those prepared in previous
measurements. Please refer other reports (e.g., Tuniz et al., 1998; Nakamura, 2003) for further
details on the quality control of the AMS measurement.
6-2-2. Target press
The sample/standard graphite should be measured by the AMS as soon as possible or stored ina desiccator to prevent reaction between the atmospheric oxygen/moisture and the iron catalyst.
To measure radiocarbon in the graphite powder using the AMS, it is loaded into an aluminum
sample holder or a target piece under high pressure, which is called the target press. Each AMS
facility decides the press pressure for the target press empirically. You must avoid crosscontamination during the target press.

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6-2-3. Ion beam
The cesium-sputter negative-ion source is generally used to extract a carbon beam from thegraphite sample. The aluminum target with the graphite sample is installed in the ion source
device and negative ions of carbon (12C–, 13C–, 14C–, 13CH–, etc.) are extracted from the graphite
sample in the target by sputtering of cesium ions from the cesium ionizer. The negative-ion source
has an advantage that negative ions of nitrogen, which are the major interfering ions in the AMS
radiocarbon measurement, are hardly formed while the negative ions of carbon are easily
generated because of its positive electron affinity. The negative ions are separated according totheir mass by the electromagnet and interfering ions are rejected from the three ion beams of
atomic/molecular weight 12, 13, and 14. Then the three ion beams are converged into one by therecombiner and injected into the accelerator.
6-2-4. Tandem acceleration
The combined ion beam injected into the accelerator is accelerated toward the high voltage
terminal charged positively in the center of the accelerator tube, where the negative ions areconverted into positive monoatomic ions (12C3+, 13C3+, and 14C3+) because its electrons are stripped.
In addition, the molecular ions are destroyed by argon gas in the charge conversion canal. Thenthe positive monoatomic ions are accelerated again in the latter half of the accelerator. The"tandem” accelerator comes from this two-step acceleration.
6-2-5. Detectors
The positive ions ejected from the accelerator are separated by the other electromagnet again
according to their mass. The ion beams of 12C and 13C are measured by the Faraday cups, which
capture charged ions in vacuum. The 14C atoms are counted by the heavy ion detector. The
detection efficiency of 14C by the AMS method is about 1%. The 14C/12C and 13C/12C ratios canbe obtained from those outputs
6-2-6. Δ14C calculation and uncertainty
The method for the Δ14C calculation from the 14C/12C and 13C/12C ratios was explained in thesection 2-2. If a precise 13C/12C ratio can be obtained by the AMS method, it should be used in
the Δ14C calculation instead of that measured by the SIRMS (6-1), because the isotopic
fractionation effect in the graphitization and AMS measurement can be corrected (Nakamura,2003). The method of the δ13C measurement should be reported with the Δ14C data. The standard
deviation derived from the replicate measurement of the same seawater sample is about 5 ‰Guideline of ocean observations Vol. 3 Chap. 9 Carbon isotopic ratios (Δ14C, δ13C) of dissolved
inorganic carbon © Yuichiro KUMAMOTO, Takafumi ARAMAKI 2019 G309EN:001-019

G309EN-17(Aramaki et al., 2010; Kumamoto et al, 2013; McNichol et al., 2010). This uncertainty includes
those derived from the sampling, stripping, graphitization, and AMS measurement, but probably
not those from the preparation and measurement of the oxalic acid standard. The contaminationsof radiocarbon in the AMS measurement and graphitization are evaluated by the AMS
measurement results of the iron powder (5-2) and 14C-free reference material (IAEA-C1
Carbonate, pMC = 0.00%), respectively. On the other hand, it is difficult to estimate that in theCO2 stripping because the preparation of 14C-free seawater is not easy.

References
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Radiocarbon from cosmic radiation. Science, 105, 576–577.
Aramaki, T. (1999): Chemical treatment method for AMS-measuement of radiocarbon in seawater samples.
Japan Atomic Energy Research Institute Research 99-007, pp.22 (In Japanese with English abstract).
Aramaki, T., T. Mizushima, Y. Mizutani, T. Yamatoto, O. Togawa, S. Kabuto, T. Kuji, A. Gottdang, M.
Klein and D.J.W. Mous (2000): The AMS facility at the Japan Atomic Energy Research Institute(JAERI). Nuclear Instruments and Methods in Physics Research, B172, 18-23.
Aramaki T, Y. Nojiri, H. Mukai, S. Kushibashi, M. Uchida, and Y. Shibata (2010): Preliminary results ofradiocarbon monitoring in the surface waters of the North Pacific. Nuclear Instruments and Methods inPhysics Research B, 268, 1222–1225.
Becker, M., N. Andersen, B. Fiedler, P. Fietzek, A. Körtzinger, T. Steinhoff, and G. Friedrichs (2012):
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Gamo, T. and Y. Horibe (1983): Abyssal circulation in the Japan Sea. Journal of Oceanographical Societyof Japan, 39, 220–230.
Gurfinkel, D. M. (1987): An assessment of laboratory contamination at the Isotrace Radiocarbon Facility.
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Honda, M., Y. Kumamoto, N. Harada, M. Kusakabe, M. Katagiri, K. Nakao, K. Hayashi, and N. Kisen(1999): Semi-automated samplepreparation system for 14C measurement on seawater sample.
JAMSTECR, 39, 1–16 (In Japanese with English abstract).
Ishii, M., H.Y. Inoue, H, Matsueda (2000): Coulometric precise analysis of total inorganic carbon inseawater and measurements of radiocarbon for the corbon dioxide in the atmosphere and for the total
inorganic carbon in seawater. Technical Reports of the Meteorological Research Institute, 40, pp.62 (InJapanese with English abstract).
Karlén I., I. U. Olsson, P. Kållberg, S. Killiççi (1966): Absolute determination of the activity of two 14C
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Key, R. M., A. Kozyr, C. L. Sabine, K. Lee, R. Wanninkhof, J. L. Bullister, R. A. Feely, F. J. Millero, C.
Mordy, and T.-H. Peng (2004): A global ocean carbon climatology: Results from Global Data Analysis
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Kitagawa, H., T. Masuzawa, T. Nakamura, and E. Matsumoto (1993): A batch preparation method forgraphite targets with low background for AMS 14C measurements. Radiocarbon, 35, 295–300.
Kumamoto, Y., A. Murata, T. Kawano, A. Watanabe, and M. Fukasawa (2013): Decadal changes in bombproduced radiocarbon in the Pacific Ocean from the 1990s to 2000s. Radiocarbon, 55, 1641–1650.
Libby, W. F., E. C. Anderson, and J. R. Arnold (1949): Age determination by radiocarbon content: worldwide assay of natural radiocarbon. Science, 109, 227–228.
Linick, T. W. (1978): La Jolla measurements of radiocarbon in the oceans. Radiocarbon, 20, 333-359.
Mckinney, C. R., J. M. McCrea, S. Epstein, H. A. Allen, and H. C. Urey (1950): Improvements in mass
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McNichol, A. P. and G. A. Jones (1992): Measuring 14C in seawater ƩCO2 by accelerator mass spectrometry.
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Oguma, S., T. Ono, and T. Asumaya (2012): Measurements of carbon and oxygen stable iosotope (δ13CDIC・
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Tsunogai S., S. Watanabe, M. Honda, and T. Aramaki (1995): North Pacific Intermediate Water studied
chiefly with radiocarbon. Journal of Oceanography, 51, 519–536.
Tuniz, C., W. Kutschera, D. Fink, G. F. Herzog, J. R. Bird (1998): Accelerator Mass Spectrometry:
Ultrasensitive Analysis for Global Science 1st Edition. CRC Press, Boca Raton, pp.400.
Verkouteren, M. and D. B. Klinedinst (2004): Value assignment and uncertainty estimation of selected lightstable isotope reference materials: RMs 8543-8545, RMs 8562-8564, and RM 8566. NIST Special
Publication 260-149 2004 Edition, pp.56.
Vogel, J. S., D. E. Nelson, and J. R. Southon (1984): Performance of catalytically condensed carbon foruse in accelerator mass spectrometry. Nuclear Instruments and Methods in Physics Research B, 233,
289–293.
Yoshikawa, H., K. Sato, K. Yoshida, K. Kobayashi, T. Miura, M. Imamura, Y. Homma, H. Nakahara, andT. Nozaki (1987): Contamination of modern carbon in sample preparation for measurement of carbon14 by accelerator MS. Bunseki Kagaku, 36, 755–759 (in Japanese with English abstract).

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Dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP)
Hiroshi OGAWA (Atmosphere and Ocean Research Institute, the University of Tokyo)

The methods for measuring DOC, DON (total dissolved nitrogen: TDN) and DOP (total dissolved
phosphorus: TDP) in seawater are published on the websites of several institutions and research projects.
●

DOC-TDN sampling guide
Hansell Lab, Rosenstiel School of Marine and Atmospheric Science, University of Miami
http://margolab.com/pubs/Margolin_et_al_2015.pdf●

Determination of DOC-TDNPICES Scientific Report34
http://www.jodc.go.jp/geotraces/docs/PICESReport34_DOC_DON.pdf
NASA Ocean Color Web Site
https://oceancolor.gsfc.nasa.gov/fsg/instrumentreports/
California Current Ecosystem LTER Program
http://cce.lternet.edu/data/methods-manual/augmented-cruises/dissolved-organic-carbon-and-totalnitrogen
HOT (Hawaii Ocean Time-series) Field Laboratory Protocols
http://hahana.soest.hawaii.edu/hot/protocols/protocols.html#
BATS (Bermuda Atlantic Time-series Study), Methods Chapter 16
http://bats.bios.edu/wp-content/uploads/2017/07/chapter16.pdf●

Consensus reference material (CRM) for DOC and TDN measurements
Hansell Lab, Rosenstiel School of Marine and Atmospheric Science, University of Miami
https://hansell-lab.rsmas.miami.edu/consensus-reference-material/index.html●

Determination of DOP
Book Chapter (provide for non-commercial research and educational use)
http://cmore.soest.hawaii.edu/summercourse/2015/documents/Karl_05-27/Karl-and-Bjorkman2015.pdf
HOT (Hawaii Ocean Time-series) Field Laboratory Protocols
http://hahana.soest.hawaii.edu/hot/protocols/protocols.html#

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and phosphorus (DOP) © Hiroshi OGAWA 2019 G310EN:001

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Particulate organic carbon (POC), particulate nitrogen (PN), andparticulate phosphorus (PP)‫ۑ‬Takeshi YOSHIMURA (Central Research Institute of Electric Power Industry)

1. Scope and field of application
This procedure describes methods for the sampling and the analysis of particulate organic carbon(POC), particulate nitrogen (PN), and particulate phosphorus (PP) in seawater samples. For analyticalmethods, the high temperature combustion (HTC) method with an elemental analyzer for POC and PN,
and the HTC and acid hydrolysis (HTC-AH) method and persulfate oxidation (PO) method for PP aredescribed. Descriptions for POC and PN are based on the JGOFS protocol (Knap et al., 1996). Sincemany analytical methods for POC, PN, and PP have been published in past studies, analysts should
select an appropriate method and establish an in-house protocol for the method based on their own
situation. The HTC method for nitrogen has been adopted as the standard method for organic nitrogen
analysis in research fields in Japan (Murakami and Shirai, 2015), and thus new technologies and related
insights for the HTC method that can be incorporated into seawater POC and PN analysis may be
published in the near future.
2. Definition
POC, PN, and PP in seawater are defined as carbon, nitrogen, and phosphorus in mainly non-volatileorganic suspended matter derived from filtering seawater onto a filter, and expressed as moles pervolume or weight of seawater. POC and PN can be analyzed simultaneously in a filter sample, and PP
is analyzed using another filter sample. Samples for POC and PN are acidified prior to analysis, thus
particulate inorganic carbon (PIC) is eliminated and we can measure POC. For PN, however, theacidification procedure cannot eliminate particulate inorganic nitrogen (PIN), thus we analyze PN but
not particulate organic nitrogen (PON). In principle, total particulate carbon (TPC) is measured if a nonacidified sample is analyzed, therefore PIC can be estimated as the difference between TPC and POC.
For PP, samples are decomposed and the liberated phosphate is analyzed, therefore particulate inorganic
phosphorus (PIP) and particulate organic phosphorus (POP) cannot be differentiated and thus PP is
measured.
3. Principles of the Analysis
For POC and PN, samples are generally combusted at temperature higher than 900 °C with oxygen.
If a tin cup is used for the sample container, the combustion temperature of the sample can reach higher
than 1800 °C. The combustion gas flows through a combustion column eliminating halogens, and thenthrough a reduction column reducing nitrogen oxides to N 2 gas and eliminating excess oxygen. N 2 andCO 2 gases are separated with gas-chromatography or gas-specific adsorptions, and then quantified witha thermal conductivity detector. Principles of POC and PN analysis by elemental analyzer are detailed
in JSAP (2008).
For PP, samples are combusted at 500 °C and then hydrolyzed by acid in the HTC-AH method or
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G401EN-2

are decomposed in persulfate solution under high temperature and high pressure conditions in the PO
method. Liberated phosphate is quantified colorimetrically using the molybdenum blue method.
Detailed procedures for colorimetry analysis are practically described in Oku (2002).
4. Apparatus
Simultaneous analysis of POC and PN requires use of an elemental analyzer, which have beendeveloped by various manufacturers. Various methods for combustion of the sample, separation of
combustion gases, and detection of the target gas are adopted by each elemental analyzer. Currently
available analyzers in Japan are reviewed in JSAP (2008).
For PP analysis, we need a hotplate, electric oven, heating device such as a hot water bath, andcolorimeter for the HTC-AH method, and an autoclave and colorimeter for the PO method. For thecolorimeter, a spectrophotometer for manual analysis or a nutrient autoanalyzer can be used.
5. Reagents
All reagents should be of an analytical reagent grade quality unless otherwise specified.
For POC and PN analyses, concentrated HCl for the removal of PIC and acetanilide (C 8 H 9 NO) for
standards are required. Acetanilide is suitable as the standard for POC and PN because it has a C:N
molar ratio of 8 that is a similar value to marine suspended particulate matter.
For PP analysis, sodium sulfate (Na 2 SO 4 ), magnesium sulfate (MgSO 4 x7H2O), and HCl in the HTCAH method, and potassium persulfate (K2S2O8) (for nitrogen and phosphorus analysis) in the PO method
are required to decompose the samples. For liberated phosphate analysis, ammonium heptamolybdate
tetrahydrate ((NH4)6MoO24x4H2O), L-ascorbic acid (C6H8O6), potassium antimony tartrate(K(SbO)C4H4O6), and potassium dihydrogen phosphate (KH2PO4) (superpure grade of Merck) for
standards are required.
6. Sampling
If subsampling of seawater is not conducted immediately after the recovery of Niskin bottles, settlingof large particles in the Niskin bottle will create a non-uniform distribution of the particles. Therefore,
the Niskin bottle should be shaken before subsampling or the entire volume should be used as the sample.
,IQHHGHGODUJH]RRSODQNWRQVKRXOGEHUHPRYHGXVLQJDQHWHJE\VLHYLQJWKURXJKDȝm meshplankton net.
Particles in seawater are collected on binder-free glass fiber filters such as Whatman 25 mm GF/F
filter. For POC and PN sampling, the filters are pre-combusted at 450 °C for 5 hours to eliminate carbon
and nitrogen contamination. For PP analysis, the pre-combusted filters are washed using an acid. For
this, a 10 mL aliquot of 1 N HCl is poured onto the filter attached to a filter funnel and the HCl removedby vacuum, and then the filter is thoroughly washed using Milli-Q water. After filtering the seawater for
PP, rinse the filter twice with 2 mL aliquots of 0.17 M Na2SO4 (Solórzano and Sharp, 1980). Filter
samples for POC and PN, and PP are wrapped in pre-combusted (550 °C, 5 h) aluminum foil and stored
DWDWHPSHUDWXUHORZHUWKDQ௅ °C. If the filter samples are stored in a plastic container, the samples
may be contaminated by carbon (Sharp, 1974). If the samples are stored in a freezer with organic
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G401EN-3

solvents or biological samples, the samples may be contaminated by carbon and nitrogen.
It is important to take a significant quantity of filter blank samples. The filter blank sample isprocessed by an identical procedure to the sample except filtering Milli-Q water is carried out insteadof the seawater sample.
7. Analytical procedures
7-1 POC and PN

Stored filter samples are dried and acidified prior to the analysis. Samples are dried in a drying ovenat 60 °C or in a freeze-dryer. Then, the samples are placed in a desiccator saturated with HCl fumes for
24 h. The air in the desiccator is kept saturated by leaving concentrated HCl in an open container in thedesiccator, which is placed under a fume hood. Thereafter, the filter samples are placed in a vacuum
desiccator with granulated NaOH to dry and remove the HCl that has detrimental effects on thesubsequent elemental analysis. To vacuum the desiccator, a water-circulating aspirator should be usedsince a vacuum pump is not resistant to corrosion by HCl. While the filter sample can be dried in open
aluminum foil that was used to store the sample in freezer, the sample has to be acidified in an acidresistant container. The sample may be contaminated by carbon if the filter sample is placed on a plastic
container (Sharp, 1974), therefore a glass container is appropriate for the acidification procedure.
Carbon and nitrogen contents of the filter sample are analyzed with an elemental analyzer following
the guidelines given by the manufacturer. Reagents for the combustion column and the reduction column
are sieved to remove any fine powder prior to packing into the column. To lower blank values thereagents should be pre-combusted prior to packing if applicable to the reagent. Then the reagents arepacked into the column appropriately with consideration for the design of a furnace (vertical or
horizontal) and the internal pressure of the columns. The analyzer should run overnight to stabilize thebaseline before sample analysis. If you use a brand-new column, it is important that equilibrium
conditions for adsorption-desorption between reagents and the analyte gas are achieved by processing
with standard samples at the maximum concentration of the working curve several times before the startof the analysis run. Empty tin cups are used as blanks to confirm the baseline stability of the analyzer.
Prior to sample analysis, a five-point working curve and three filter blank samples are analyzed. A blankand standard sample with a predetermined concentration LVPHDVXUHGHYHU\௅VDPSOHVWRHQVXUHWKDW
problems have not developed. Details of the preparation, analysis run, and maintenance of an analyzer
are described in JSAP (2008).
7-2 PPFirst, an example procedure of the HTC-AH method (Solórzano and Sharp, 1980) is described. A
filter sample is placed in a glass vial with a screw cap. A two mL aliquot of 0.017 M MgSO4 is poured
into the vial, and the solution in the vial without the cap is dried on a hotplate. After combusting thesample in an electric oven at 500 °C for 2 h, the sample is treated in 0.2 M HCl in the vial with the cap
at 80 °C for 30 min using a hot water bath. After cooling, the sample solution is filtered through a 0.22
µm pore size syringe filter. A four mL aliquot of the filtrate is added into a 50 mL volumetric flask andGuideline of ocean observations Vol. 4 Chap. 1 © Takeshi YOSHIMURA 2016 G401EN:001-006

G401EN-4

make to 50 mL with Milli-Q water, and then the phosphate concentration is colorimetrically analyzed.
It is important to confirm beforehand that the acid concentration of the sample solution does not inhibit
color development of the molybdenum blue method. Although the sample solution may be neutralizedwith NaOH solution when the acid concentration is high enough to inhibit molybdenum blue color
development, caution is required because excess addition of NaOH make the solution alkaline and thengenerates precipitation that adsorb and remove the phosphate from the sample solution. This may cause
a serious underestimate or no detection of phosphate in the sample solution.
Second, an example procedure of the PO method is described. A filter sample is placed in potassium
persulfate solution in an airtight container, and treated under high temperature and high pressure using
an autoclave. After cooling, the sample solution is filtered through a 0.22 µm pore size syringe filter.
Since a high concentration of potassium persulfate inhibits color development of molybdenum blue
method, the concentration is reduced to less than 2 %. Finally the phosphate concentration is measured
colorimetrically with the molybdenum blue method. Although the PO method of Parsons et al. (1984)
or equivalent has been widely used, it has been reported that the PO method may underestimate the PP
concentration compared to the HTC-AH method. However, Suzumura (2008) shows that an increase inpotassium persulfate concentration of the previous PO method under 120 °C for 30 min conditions cangenerate the same PP concentration to the HTC-AH method. They conclude that the improved PO
method is a simpler procedure and a less time-consuming method than the HTC-AH method.
Regardless of the PP decomposition method, liberated phosphate is colorimetrically quantified withthe molybdenum blue method of Parsons et al. (1984) for a single solution method or Hansen and
Koroleff (1999) for a double solution method. Since the color development of molybdenum blue can beinhibited due to the combination of the decomposition method and colorimetry method, priorexaminations to confirm a normal color development are necessary. Similarly, a manual and an
automated analysis can generate a different color development, so it is important that the phosphateconcentration in the sample solution has to be calculated with a working curve using standards in thesame matrix to the sample solution.
8. Factors for errors
POC, PN, and PP have to be analyzed to a high precision using a small amount of sample, andtherefore factors leading to errors should be eliminated as much as possible. A tin cup for the POC andPN sample container should be washed with ethanol and acetone to reduce absolute values andvariability of blanks. If any volume of air is contained in a sample container with a sample filter, nitrogenin the air also is detected with the nitrogen derived from the sample and thus a cause of contaminationȝL of air is equivalent to 1 ȝJRI nitrogen). Although the organic and inorganic carbon and nitrogendissolved in an approximately 0.1 mL aliquot of the seawater that is retained on a GF/F filter as a residueof filtered seawater does not affect the carbon and nitrogen values derived from the sample itself (Sharp,1974), it has not been determined whether adsorption of dissolved matter in the sample seawater to the
GF/F filter through filtering the sample seawater has a significant impact on the sample analysis value.
Karl et al. (1998) and Morán et al. (1999) reported that a significant amount of dissolved organic carbon(DOC) produced during an incubation for the measurement of primary production with 14C method is
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G401EN-5

adsorbed onto a GF/F filter. Moran et al. (1999) reported that adsorption of DOC onto a GF/F filter is a
cause of a 2–4 times higher value for several liters of filtered POC sample derived from a Niskin bottle
than for several hundred liters filtered POC sample derived from an in situ pump. Wang et al. (2011)
corrected their POC concentrations by subtracting 2 ȝmol of carbon from the detected value of a filter
sample to cancel out the effect of DOC adsorption. Adsorption of dissolved matter onto a GF/F filter
can also cause a positive error for nitrogen and phosphorus, but the extent to which nitrogen andphosphorus adsorb onto a filter has not been clarified.
Furthermore, the utilization of a reference material (RM) is recommended to manage the quality ofanalytical results and to establish comparability to the results reported by different analysts. For example,
an in-house secondary standard (plankton sample) for POC and PN analysis and apple leaves (NIST
1515) for PP analysis are used as a check standard in the Hawaii Ocean Time-series Program(http://hahana.soest.hawaii.edu/hot/methods/results.html).
Environmental

Studies(NIES)

distributes

In

RMs

Japan,
for

National

environment

Instituteformeasurements(http://www.nies.go.jp/labo/crm/index.html). In their list, water hyacinth (Eichhornia crassipes) (NIESCRM No. 29) has a certified value for phosphorus and a reference value for carbon and nitrogen, andthus this can be used as a RM for POC, PN, and PP analysis. A dataset for carbon, nitrogen, andphosphorus in particulate organic matter in the global ocean has recently been established by Martiny
et al. (2014), and it is expected that the dataset is utilized in a wide range of research including modelingstudies. More high quality data derived through better sampling and analytical protocols as reported here
are needed to better understand the marine biogeochemical cycle of carbon, nitrogen, and phosphorus.
References
Hansen, H. P. and F. Koroleff (1999): Determination of nutrients, p. 159–228. In Methods of Seawater Analysis,
Third Edition, edited by K. Grasshoff, K. Kremling, and M. Ehrhardt, Wiley-VCH Verlag GmbH,
Weinheim, Germany.
Japan Society for Analytical Chemistry (JSAP), The Association of Organic Micro-analysts (2008): Practical
Microorganic Analysis. Mimizukusha, Tokyo, 195 pp (in Japanese).
Karl, D. M., D. V. Hebel, K. Björkman, and R. M. Letelier (1998): The role of dissolved organic matter releasein the productivity of the oligotrophic North Pacific Ocean. Limnology and Oceanography, 43, 1270௅1286.
Knap, A., A. Michaels, A. Close, H. Ducklow, and A. Dickson (1996): Protocols for the Joint Global Ocean Flux
Study (JGOFS) Core Measurements. JGOFS Report Nr. 19, vi+170 pp. Reprint of the IOC Manuals andGuides No. 29, UNESCO 1994.
Martiny, A. C., J. A. Vrugt, and M. W. Lomas (2014): Concentrations and ratios of particulate organic carbon,
nitrogen, and phosphorus in the global ocean. Scientific Data, 1, 140048, doi:10.1038/sdata.2014.48
Moran, S. B., M. A. Charette, S. M. Pike, and C. A. Wicklund (1999): Differences in seawater particulateorganic carbon concentration in samples collected using small- and large-volume methods: the importance of
DOC adsorption to the filter blank. Marine Chemistry, 67, 33௅42.
Morán, X. A., J. M. Gasol, L. Arin, and M. Estrada (1999): A comparison between glass fiber and membranefilters for the estimation of phytoplankton POC and DOC production. Marine Ecology Progress Series, 187,
31௅41.
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G401EN-6

Murakami, T. and Y. Shirai (2015): Organic elemental analysis by combustion method. BUNSEKI, 2015, 108௅
114 (in Japanese).
Oku, O. (2002): Know-How for Spectrophotometry: Qualitative Analysis of Silicic Acid, Phosphate, and Nitrate.
Gihodoshuppan, Tokyo, 137 pp (in Japanese).
Parsons, T. R., Y. Maita, and C. M. Lalli (1984): A Manual of Chemical and Biological Methods for Seawater
Analysis. Pergamon Press, Oxford, 173 pp.
Sharp, J. H. (1974): Improved analysis for “particulate” organic carbon and nitrogen from seawater. Limnology
and Oceanography, 19, 984௅989.
Solórzano, L., and J. H. Sharp (1980): Determination of total dissolved phosphorus and particulate phosphorus innatural waters. Limnology and Oceanography, 25, 754–758.
Suzumura, M. (2008): Persulfate chemical wet oxidation method for the determination of particulate phosphorus
in comparison with a high-temperature dry combustion method. Limnology and Oceanography: Methods, 6,
619–629.
Wang, G., W. Zhou, W. Cao, J. Yin, Y. Yang, Z. Sun, Y. Zhang, and J. Zhao (2011): Variation of particulateorganic carbon and its relationship with bio-optical properties during a phytoplankton bloom in the Pearl
River estuary. Marine Pollution Bulletin, 62, 1939–1947.

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G402EN-1

Biogenic silica‫ۑ‬Fuminori HASHIHAMA (Tokyo University of Marine Science and Technology)

1.

Introduction
Biogenic silica (BSi) is an amorphous silica that is produced primarily by diatoms, silicoflagellates,

radiolarians, and sponges. Among these organisms, planktonic diatoms are an important group and are
currently responsible for 40% of primary production in the world’s oceans (Nelson et al., 1995).
Assimilation of dissolved silicic acid (DSi) by diatoms, dissolution of diatom frustules, and downward
export and sedimentation of diatom debris are the major processes in the marine silicon cycle. To
understand these processes, information regarding BSi is generally essential.
Analytical procedures for the measurement of BSi include wet-alkaline extractions, X-ray
diffraction, and infrared absorption.

Among them, the wet-alkaline extraction method appears to be

the most versatile for the BSi measurement of suspended particulate matter (DeMaster, 1991). Thismethod involves the alkaline extraction of BSi on filter samples and the subsequent determination of
DSi using conventional colorimetry.

Herein is described a modified literature procedure using NaOH

for the extraction (Paasche, 1973).

This procedure features a more rapid extraction and higher

extraction efficiency than other wet-alkaline extraction methods (Krausse et al., 1983).
2.

Sampling
Water samples should be collected using a silicon-free, alkaline- and acid-cleaned sampler such asa Niskin or Van Dorn sampler.

Water collected in the sampler is then dispensed into a plastic bottle(and not a glass bottle) directly or using a vinyl tube. The use of silicon tubing instead of the vinyl
tubing should be avoided, because silicon tubing can contaminate the BSi.

The required sample

volume, approximately equal to the filtration volume, is roughly several tens of milliliters to several
liters for the coastal, high latitude, and equatorial upwelling regions; and several liters to several tens ofliters for subtropical and equatorial warm pool regions.

In practice, the required sample volume isdetermined based on the analytical detection limit of the colorimetry and the previously reported BSi
concentration in a target region (see below).
3.

Filtration
The sample water is accurately measured using a plastic graduated cylinder or a plastic bottle ofknown-volume (such as the plastic bottle used for sampling). The measured water is filtered using aplastic filtration device (with no glass components). If silicon packing is used in the filter holder, it
should be replaced with a silicon-free packing, such as Teflon.

There are many filters used forcollecting suspended particulate matter, and a polycarbonate filter, such as a Whatman Nuclepore filter(GE Healthcare), is appropriate for BSi determination. A glass fiber filter cannot be used because it
would introduce significant silicon contamination. A polycarbonate filter with a 47 or 25 mm diameteris commonly used, and its 0.4௅0.8 ȝm pore size is effective for collecting most diatoms.
is performed using an aspirator with a gentle suction of <150௅200 mmHg.

The filtration

After the filtration, theGuideline of ocean observations Vol. 4 Chap. 2 © Fuminori HASHIHAMA 2016 G402EN:001-003

G402EN-2

particulate matter attached to the inside of the filter funnel, and the DSi adsorbed onto the filter, arewashed with several tens of milliliters of low-DSi filtered seawater. The low-DSi filtered seawater isprepared by passing oligotrophic open water through a 0.2 ȝm pore size polycarbonate filter. The filter
sample is folded and placed into a polypropylene centrifuge tube, e.g., 28 mL Oak Ridge Centrifuge
Tubes, Nalgene.

A tightly sealable and heat-resistant tube is preferred because it will be held at 100ºC during the extraction of BSi (see below).
4.

Extraction procedure
If a drying oven is available in the field, the filter sample is immediately dried at 60 ºC for

approximately 2 h.

However, if one is unavailable in the field, the filter sample is temporarily storedat ௅20 ºC, and after the field observation is complete the sample is dried at a land-based laboratory.
BSi on the filter sample is extracted according to a procedure using a NaOH solution.
0.2 M NaOH is added to a filter-containing polypropylene centrifuge tube.

First, 10 mL of

At this point, the screw topof the tube should be wrapped using a Teflon seal tape to ensure a tight seal.

After the tube is sealed

and the filter is soaked in the NaOH solution, the sample is placed in a water bath at 100 ºC for 15 min.
The sample is then cooled to ambient temperature and neutralized using 10 mL of 0.2 M HCl.
5.

Colorimetry
BSi in the sample should be transformed into DSi after the extraction. The DSi concentration isthen measured using a molybdenum blue colorimetry (see Vol. 3, Chap. 2).
During the DSi measurement, the blank and the matrix of standard solutions should be preparedusing equal volumes of 0.2 M NaOH and 0.2 M HCl.

A correction of filter blank is generally not

required because Nuclepore filers are not contaminated with BSi.

However, if other filter types areused, the absorbance of filter blank might require subtraction from the absorbance of the sample. A
filter blank is prepared through the extraction and neutralization of a fresh filter that has not been
exposed to sample water.
6.

Calculation
From the DSi concentration determined using colorimetry, the BSi concentration is calculated asfollows:
BSi (ȝM) = DSi (ȝM) * 0.02 (L) / FV (L)where FV is the filtered volume, and 0.02 that is multiplied by DSi concentration is the total volumeof 0.2 M NaOH and 0.2 M HCl used.
The FV is a critical term because it directly influences on the detection of DSi.

If given a detection

limit of 0.1 ȝM DSi and an ambient concentration of 0.01 ȝM BSi, the FV is calculated as follows:
0.01 (ȝM BSi) = 0.1 (ȝM DSi) * 0.02 (L) / FV (L)FV (L) = 0.2
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G402EN-3

In this case, >200 mL FV is required for the detection of BSi. Therefore, the DSi detection limit
and the ambient BSi concentration should be reviewed before sampling, and an appropriate sample
volume should be collected for the accurate determination of BSi.
7.

Remarks
The wet-alkaline extraction method appears to be the most versatile, but it requires particularattention when used for samples collected from estuarine and coastal regions.

In these regions,lithogenic silica (LSi) contributes significantly to the total particulate silica and its dissolution during
the alkaline extraction often results in overestimation of the BSi concentration (Ragueneau and Tréguer,1994).

To determine the BSi concentration in high-LSi water, a method that corrects for thecontribution of LSi to BSi should be applied (Ragueneau et al., 2005).
References
DeMaster, D. J. (1991): Measuring biogenic silica in marine sediments and suspended matter, p. 363௅368. In
Marine Particles: Analysis and Characterization, edited by D. C. Hurd and E. W. Spenser, American
Geophysical Union.
Krausse, G. L., C. L. Schelske, and C. O. Davis (1983): Comparison of three wet-alkaline methods of digestionof biogenic silica in water)UHVKZDWHU%LRO௅
Nelson, D. M., P. Tréguer, M. A. Brzezinski, A. Leynaert, and B. Quéguiner (1995): Production and dissolutionof biogenic silica in the ocean: Revised global estimates, comparison with regional data and relationship tobiogenic sedimentation. Global %LRJHRFKHP&\FOHV௅
Paasche, E. (1973): Silicon and the ecology of marine plankton diatoms. I. Thalassiosira pseudonana (Cyclotellanana) grown in a chemostat with silicate as limiting nutrient0DU%LRO௅
Ragueneau, O., and P. Tréguer (1994): Determination of biogenic silica in coastal waters: applicability and limitsof the alkaline digestion method0DU&KHP௅
Ragueneau, O., S. Nicolas, Y. Del Amo, J. Cotton, B. Tardiveau, and A. Leynaert (2005): A new method for themeasurement of biogenic silica in suspended matter of coastal waters: using Si:Al ratios to correct for themineral interference&RQWLQHQWDO6KHOI5HV௅

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G403ENr1-1

Carbon and Nitrogen Stable Isotopes in Particulate Organic Matter
Yu UMEZAWA (Tokyo University of Agriculture and Technology)

1.

Introduction
Particulate Organic Matter (POM) in the ocean is an important food source for a variety of the marineorganisms such as filter feeders and fishes. POM also functions as a reservoir of dissolved organic matter(DOM) and nutrients, which are generated during bacterial decomposition of POM, especially inoligotrophic pelagic waters. Furthermore, evaluation of the export flux of POM into the deep layers of
the ocean is important for comprehending the Earth’s carbon, nitrogen and phosphorus cycles.
Carbon and nitrogen stable isotopes (13C・15N) in POM in the euphotic layer primarily reflect the13C・15N values of source materials, that is, dissolved inorganic carbon (DIC) and dissolved inorganic
nitrogen (DIN), which are taken up by phytoplankton. POM isotopes also reflect the mixed POM carried
from the other sources such as rivers. In addition to source values, the isotope values of POM reflect
processes including isotope discrimination (kinetic isotope effect), such as due to prior uptake andbiosynthesis of lighter isotopes by phytoplankton, and heterogenic modification such as due to bacterial
decomposition of specific parts of the POM pool.
Of course we need to pay special attention to the interpretation of 13C・15N values in POM, because
POM itself is an aggregation and/or mixture of different materials (i.e., phytoplankton, zooplankton andorganic debris). Despite these potential complications, 13C・15N values can be an effective tool forinvestigating food web dynamics and material cycles (i.e., the source and pathways of the materials) in
the aquatic systems, as far as we understand the characteristics of stable isotopes and interpret values in
the context of other physical, chemical and biological parameters (Tables 3-1, 2).
The concentration of POM is variable in space and time, and therefore, field and laboratory sample
processing for POM 13C・15N can be time-consuming since we need to collect many samples to capture
the spatio-temporal variation, as well as needing to adjust filtration volumes (see below). However POM
13C・15N analyses should be considered an important parameter in field observations of the ocean,
now and in the future. It is also advantageous that the outsourcing of isotope analyses is available
relatively cheaply, costing 2,000 to 5,000 JPY per sample, and the number of mass spectrometers inuniversity or research institutes is increasing.
In this section, the basic protocols and devices for POM sampling, sample processing, and 13C・
15N analyses are briefly explained. Because these protocols are not completely unified between
researchers, previous articles dealing with 13C・15N analyses should also be consulted, depending on
the conditions (e.g., Teece and Fogel, 2004; Miyajima, 2008; Ogawa et al., 2010; Ogawa et al., 2013).
POM 13C ・ 15N analyses are generally conducted using elemental analyzer-isotope ratio mass
spectrometry (EA-IRMS), with POM generally defined as the particles trapped on a glass fiber filter
with a pore size of 0.7 or 0.8 m (e.g., GF/F, Whatman). Filters with smaller pore size (e.g., GF-75,
ADVANTEC) may be used in surface waters of the tropical and subtropical ocean, where the biomassof pico-plankton is not negligible. The appropriate filter pore size should be selected depending on theconditions of the target ocean, and the purpose of the observation.
Guideline of ocean observations Vol. 4 Chap. 3 Carbon and Nitrogen Stable Isotopes
in Particulate Organic Matter © Yu UMEZAWA 2019 G403ENr1:001-009

G403ENr1-2

This chapter focuses on 13C and 15N analysis of bulk POM according to the above definition. On
the other hand, it is possible to analyze 13C and 15N in size-fractioned POM and those in chlorophylls
and amino acids extracted and purified from POM. By analyzing these compound-specific isotopic
values, there is an advantage to understand the phytoplankton dynamics and the trophic level of POM(i.e., contribution of heterotrophs and related debris). Please refer to previous literatures for sample
processing, analytical methods and applications for these parameters (e.g., Sato et al., 2006; McCarthy
et al., 2007; Yamaguchi & McCarthy, 2018).

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G403ENr1-3

Table 3-1. Factors causing variation in  C-POM and associated fluctuations of other parameters
13（※ An opposing pposite shift in 13 C values is often caused by the reverse case ）Factors causing a relative increase of 13 C-POM

Probable phenomena observed simultaneously
1) Increase in irradiance, temperature, and nutrients supply

・Increase in photosynthesis (DIC uptake)2) Increase in photosynthetic pigments (e.g., chlorophyll)3) Increase in 15 N values

Factors causing a relative decrease of 13 C-POM
・Supply of DIC with lighter  C (e.g., freshwater DIC)
13

Probable phenomena observed simultaneously
1) Decrease in salinity
1) Increase in C/N ratio ( higher C/N ratio of terrestrial plants )・Contribution of terrestrial plants and freshwater plankton

2) Decrease in salinity
3) Increase in organic polymers in vascular plants (e.g., lignin)

Table 3-2. Factors causing the variation of 15 N-POM and associated fluctuations of other parameters（※ An opposing pposite shift in 13 C values is often caused by the reverse case ）Factors causing a relative increase of 15 N-POM
・Contribution of wastewater-derived DIN with high 15 N

Probable phenomena observed simultaneously
1) Decrease in salinity, Short distance from the shore
1) Decrease in dissolved oxygen

・ Increase in  N-nitrate due to denitrification
152) Increase in denitrifying bacteria (e.g., molecular approach)3) Increase in 18 O-nitrate
1) Increase in irradiance, temperature, and nutrients supply
2) Increase in photosynthetic pigments (e.g., chlorophyll)

・Increase of photosynthesis (DIN uptake)3) Increase in  C-DIC
134) Decrease in DIN concentration by uptake(Inverse correlation between 15 N-POM & log-transformed DIN)

・Contribution of upwelling-derived NO3 to primary
production, compared with N2 -fixation in pelagic water

1) Decrease in temperature, Increase of salinity
2) Developed vertical mixing
1) Increase in heterotrophs (microscopic analysis)

・Higher contribution of heterotrophs-derived organic matter( Increase of amino acid trophic level in POM)

with relatively heavier  N2) Decrease in Chl/POC

153) Increase in water depth below euphotic zone
Factors causing a relative decrease of 15 N-POM

Probable phenomena observed simultaneously
1) Increase in 18 O-nitrate・Contribution of rainwater-NO3 to primary production2) Decrease in salinity
3) Increase in DIN/P ratio in nutrient

・Increase in nitrogen fixation

・Contribution of remineralized NH4 (lower f -ratio)
compared with NO3 from deep water in pelagic ocean

1) Increase in nitrogen fixing bacteria
2) Increase in photosynthetic pigment, phycoerythrin
1) Increase in small-sized phytoplankton
2) Increase in nitrifying bacterial activity3) Development of stratification

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2.

Sampling
For the analysis of 13C・15N in organic matter, it is recommended to prepare samples such thatthey contain 60-100 g nitrogen in order to minimize the effect of contamination (i.e., atmosphericnitrogen, and organic matter attached to the glass fiber filter and tin capsules) on the real isotope valuesof the samples. The amount of carbon is not such a focus because the carbon to nitrogen ratio in naturalorganic matter is generally larger than 1. On the other hand, it is necessary to minimize the volume ofglass fiber filter used and to maintain good analysis conditions, especially for small samples (see 3-4)
because the incombustible glass fiber filters accumulate in the combustion column as debris often
causing incomplete combustion of organic matter and blockage of gas passing, resulting in erroneous13C・15N values. Therefore, it is necessary to change the volume of water filtered depending on theconcentration of POM. For example, c.a. 10 L or more may be necessary over coral reefs, in the surface
layers of offshore waters, and in very deep layers, compared to 2 or 10 L in the chlorophyll maximum
layer or just several hundred mL for samples taken from a phytoplankton bloom in the coastal area.
Increasing the amount of POM by increasing the water volume of the filtration results in an increase infiltration time. Furthermore, as POM trapped on the filter increases, it may partly fill the filter pores andthen small particles less than the nominal pore size may also get trapped on the filter. We need to takecare regarding the volume of water chosen for filtration to prevent an imbalance in the size of POM
collected on the filter (Uematsu et al., 1978).
Seawater samples for POM 13C・15N are generally collected across water depths using a water
sampler (e.g., Van Dorn sampler or Niskin water sampler equipped into RMS: Rosette Multibottle
Samplers), and the water is transferred to a plastic container through a tube via a nylon net of 200 or
300 mesh size to remove large zooplankton or debris. Surface seawater can be collected by a bucket andtransferred to the container with a funnel containing the nylon net. Water samples are then filtered on
pre-combusted (3 hours at 450°C to remove the organic matter) glass fiber filters using an aspirator tokeep suction pressure about 20－25 kPa（150－200 mmHg）to prevent larger particles from passing
the filter. The entire water sample is generally introduced into the filtration system continuously using
a siphon system, but it is necessary to regularly shake the container to keep an even POM concentrationin suspension. At the final step of the filtration, rinse the inner wall of the funnel with filtered seawater,then wash the salt out of the filter with a few ml of the ultrapure water. Ammonium carbonate solutionis also used for washing to minimize the possibility of lysis of phytoplankton cells due to the osmolardifference (e.g., Uematsu et al., 1978), but there is a risk of ammonium contamination in water samples
for nutrient analysis during the sample processing. After filtration, the filter is removed from filter folder
by forceps while maintaining suction pressure, and placed into pre-combusted aluminum foil or a petri
dish and stored at a temperature of -20°C.
As suggested in Tables 3-1, 2, there are many environmental factors causing shifts in 13C・15N
values in POM. To properly interpret POM 13C・15N values in the context of environmental conditions,collection of not only basic parameters such as water temperature, salinity, chlorophyll, and dissolved
oxygen, but also other data sets such as nutrients, predominant phytoplankton species, and bacteria may
also be required during the field survey depending on the study purpose.
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3. Sample Processing
Filter samples stored in the freezer are dried in a vacuum freezing oven or heating oven at about
60°C, and transferred to clean glass petri dish one by one. The filter samples are then stored in a tightbox with a beaker of 20-40 ml concentrated hydrochloric acid (conc. HCl) for 1 day to remove inorganiccarbon (e.g., HCO3-, CaCO3) by acid fumigation. After acidification, the petri dishes are placed in a
vacuum desiccator equipped with no metal parts (or vacuumed by water aspirator) from several days to
1 week. There is the option to place granular sodium hydrate together with the samples to promote
neutralization of the acid gas. At the final step, the filter is completely dried on a hotplate or in the ovenfor 1 day, and stored in a desiccator with silica gel.
In the next step, the marginal white portion of the filter, which contains no organic matter, is removed
using ethanol-washed forceps and scissors to minimize the amount of glass fiber filter relative to theamount of organic matter. Some researcher also slightly peel the back side of the filter for the same
purpose. However, this is not recommended, because, although this method may increase the number ofsamples analyzed with single combustion column, carbon and nitrogen amounts are then underestimatedand 13C・15N values can potentially deviate from the real values. Glass fiber filter samples are wrappedin a tin or silver capsule, and tightly folded into a pellet using 2 set of forceps. Generally organic matter,
especially organic carbon, attaches to the surface of tin capsule. The contamination of organic mattercan be minimized by soaking and washing with a clean organic solvent such as methanol or acetone.
The use of disk-type smooth tin foil without wrinkles or smaller sized tin capsules decreases the amountof contaminated organic matter. Furthermore, in the case of silver capsules having a higher melting point,
pre-combustion at 400-450°C effectively decreases the organic matter contamination (Ogawa et al.,2010).
To adjust the amount of organic matter to one appropriate for analysis, the filter is divided after
confirmation that the samples were homogenously trapped into the filter. The relative weights of thewhole filter and the filter part are measured, and used for calculation of organic matter concentration in
the sample (e.g., mg-C/L, mg-N/L) based on the following equation.
POC conc. (mg-C/L) =POC (mg-C) in the filter part x

weight of whole filter (mg)weight of the filter part (mg)x1
filtration volume (L)When the amount of organic matter is large, some oxidant such as vanadium pentoxide (V2O5) orcobalt oxide (Co2O3) may be added with POM samples to promote complete combustion of the organic
matter (Kanda et al., 1998), after checking the blank size (i.e., the contaminated organic matter in theoxidant). When tin capsules burn with a flash in the combustion column at about 1000°C, thetemperature increases up to above 1800°C. Therefore, a small piece of tin-foil placed on the POM
sample and wrapped together with the filter may promote complete combustion of the POM in the glass
fiber filter. The sample roughly compressed with forceps can be further compacted with a handy tablet
punch & dies with a pressure of 3 – 5 MPa to completely remove atmospheric nitrogen gas contained in
the glass fiber. Atmospheric nitrogen remaining in the filter can cause overestimation of nitrogen
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contents and inaccurate estimation of the 15N of the samples. In order to accurately evaluate thecontamination of atmospheric nitrogen, it is necessary to prepare blank filter samples in the same manneras samples (see 3.4). The samples should be kept in a desiccator until analysis, but it is recommended
they should be analyzed as soon as possible to minimize contamination by atmospheric nitrogen.
4. Sample analysis
The 13C・15N values of the filter samples in tin capsules are determined by EA-IRMS (Elemental
Analyzer coupled to Isotope Ratio Mass Spectrometry) in the same way as the analysis of solid organic
samples.
Generally 13C・15N values in the samples are first determined relative to the 13C・15N values inreference CO2 and N2 gas, respectively, and then this temporal values are converted to real values
referring to the difference between the real values and measured values of standards having known 13C・
15N values (Fig. 3-1). The 13C and 15N values often shift depending on the amount of carbon or
nitrogen in the sample. In particular 15N values in small samples tend to be lighter than the real values.
Ideally the size of samples should be adjusted so that they contain enough nitrogen for the 15N values
to be minimally shifted, however this is often difficult for the POM samples (Fig. 3-1). The massdependent shift in 15N values of standards can be modelled by a regression fit, and the real stable isotope
values of unknown samples then corrected based on the mass of N injected and the regression equation
for the standards (Fig. 3-1).
Amino acids having similar C/N ratio to that of particulate organic matter (e.g., 3.0 for alanine, 5.0
for proline, and 9.0 for phenylalanine) are often used as standards. These standard amino acids are
generally secondary standards produced based on the primary international standard samples and areavailable through many domestic or foreign companies. The basic mechanisms of EA-IRMS, the detailsof machine-specific operation (e.g. based on the apparatus of Thermo Fisher Scientific Inc.), and details
on the analysis of the data obtained are also available in previous reports (e.g., Brand, 2004, Ogawa etal., 2013) in addition to the manuals of the product makers.

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Measurable output range (Vs)with appropriate calibration

Desirable output range (Vs) for SI（=amount of organic matter）

Measured values of Standard
samples & regression line

Y = f (x)f (c) (‰)

a (‰)

Measured value of unknown sample(c(v), a(‰))

b (‰)

f (x) - b

Actual value of standard sample
Actual value of unknown samplea-( f (c) -b) (‰)

0.0

c (v) 40.0

80.0

120.0

Output Voltage (V)Figure 3-1. Calculation of actual stable isotope values of unknown
samples based on the analyses of standards
Several points about which we should be extra careful in the analysis of filter samples having lower
organic matter include: 1) to precisely measure the blank sample (i.e., tin capsule and glass fiber filter)and compensate the measured values of targeted samples by subtracting the blank size; 2) to confirm
the accuracy and repeatability of 13C and 15N values in standards having similar carbon and nitrogencontent to that of targeted samples through repeated analyses; and, 3) to monitor the deterioration of theanalytical conditions (e.g., clogging and contamination in the combustion column) and make a proactive
decision regarding suspension of the analysis. Deterioration of the analytical conditions can beobjectively judged based on a shift of 13C, 15N and C/N ratios in the standards, a shift in carrier gas
flow speed (ml/s) and retention time of the sample peaks, an increase the background values, andinstability in repeatedly injected reference gases.
As mentioned in Section 3., nonflammable glass fiber filters accumulate as debris in the combustion
column, and potentially cause incomplete combustion of organic matter and/or block the passage of thecarrier gasses. These phenomena cause delays in the retention time of the sample peak and peak tailing,
resulting in a shift in 13C and 15N values when the peaks overlap with the reference gas peak and thepeak is not correctly evaluated. An inner ceramic or quartz tube placed in the combustion column may
improve analytical conditions for glass fiber filter samples. Since the inner tube is easily replaced witha new tube when the symptoms of incomplete combustion are observed, many more filter samples canbe analyzed using the same combustion and reduction columns (Kanda et al., 1998; Ogawa et al., 2013).
Furthermore, quartz tubes with smaller internal diameter (φ8-10 mm) than the normal tubes with
φ14-16 mm ID decrease the dilution ratio of generated gasses (CO2 and N2) with carrier He gas, andare therefore useful for increasing the accuracy of analyses of samples with lower organic matter (Ogawa
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et al., 2010). Although the number of the samples that can be analyzed in the narrower tube is smaller
than that of normal tubes, an increase in the analytical accuracy for small samples is an indispensable
merit, in addition to saving the materials filled in the quartz tubes.
As introduced above, special care is needed for the analysis of filter samples. A longer time is required
for these analyses to minimize interference with the reference gas peaks due to incomplete combustion
and tailing peaks. Manual modification of the peak width on the chromatogram and calibration of thevalues based on the standards and blanks are needed for each sample analysis. Unlike the analyses ofanimal and plant samples, the accurate analysis of POM filter samples will be accomplished based on
the accumulated experience and techniques used by each researcher.
References
Brand, W. A. (2004): Mass Spectrometer Hardware for Analyzing Stable Isotope Ratios. p.835-856. In Handbookof Stable Isotope Analytical Techniques, Vol. 1, Edited by P.A. de Groot, Elsevier, Amsterdam.
Kanda, J., K. Sada, I. Koike, and K.Yokouchi (1998): Application of an automated carbon-nitrogen analyzer forelemental and isotopic analysis of samples retained on glass-fiber filters. International Journal ofEnvironmental Analytical Chemistry, 72, 163-171.
McCarthy M.D., R. Benner, C. Lee, and M.L. Fogel (2007): Amino acid nitrogen isotopic fractionation patterns
as indicators of heterotrophy in plankton, particulate, and dissolved organic matter. Geochim. Cosmochim.
Acta, 71, 4727–4744.
Miyajima, T. (2008) Chapter 4: Estimation of the source of particulate organic matter in the estuary. P.163-186,(In) Stable Isotopes in Environmental Assessment of Watersheds –Progress Towards an Integrated Approach(eds. T. Nagata and T. Miyajima), Kyoto University Press, Kyoto. (in Japanese)
Ogawa, N., and N. Ogura (1997): Dynamics of Particulate Organic Matter in the Tamagawa Estuary and Inner
Tokyo Bay. Estuar. Coast. Shelf S., 44, 263-273.
Ogawa, N. O., T. Nagata, H. Kitazato, and N. Ohkouchi (2010): Ultra sensitive elemental analyzer/isotope ratio
mass spectrometer for stable nitrogen and carbon isotopic analyses. P.339-353, In Earth, Life, and Isotopes,
edited by N. Ohkouchi, I. Tayasu, K. Koba, Kyoto University Press, Kyoto.
Ogawa, N. O., Wang, S., Shinohara, H., and N. Ohkouchi, (2013): Protocol for precise analyses of stable isotope
ratio－Carbon and nitrogen stable isotope analyses－, Japan Chemical Analysis Center (in Japanese)
Sato, T., T. Miyajima, H. Ogawa, Y. Umezawa, and I. Koike (2006): Temporal variability of stable carbon andnitrogen isotopic composition of size-fractionated particulate organic matter in the hypertrophic Sumida River
Estuary of Tokyo Bay. Estuarine, Coastal and Shelf Science, 68, 245-258.
Teece, M. A., and M. L. Fogel (2004): Preparation of Ecological and Biochemical Samples for Isotope Analysis.
p.177-202. In Handbook of Stable Isotope Analytical Techniques, edited by P.A. de Groot, Elsevier,
Amsterdam.
Uematsu, M., Minagawa, M., Arita, H., and Tsunogai, S. (1978): Determination of dry weight of total suspended
matter in seawater, Bulletin of the Faculty of Fisheries Hokkaido University, 29(2), 164-172. (In Japanese)
Yamaguchi Y. T., and M. D. McCarthy (2018): Sources and transformation of dissolved and particulate organic
nitrogen in the North Pacific Subtropical Gyre indicated by compound-specific δ15N analysis of amino acids.

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Geochimica et Cosmochimica Acta, 220, 329-347.

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Algal pigments
Koji Suzuki (Hokkaido University)

1. Introduction
Concentrations of chlorophyll a or total chlorophyll a (chlorophyll a + divinyl chlorophyll a) haveoften been used as indices of phytoplankton (cyanobacteria and eukaryotic microalgae) biomass. All
marine phytoplankton except cyanobacterium Prochlorococcus possess chlorophyll a as the principal
photosynthetic pigment (Jeffrey et al., 2011), whereas Prochlorococcus, which occurs in sunlit
subtropical and tropical waters, contains divinyl chlorophyll a (Chisholm et al., 1998). These
chlorophylls can be quantified easily by fluorometry or the other methods. However, it is well known
that algal cellular chlorophyll a concentration can significantly change with differences among species
and/or their habitats (intensity and quality of light, nutrient availability, etc.; Harrison e t

al.,

1977;

Falkowski and Owens, 1990). Therefore, in general, it is difficult to convert chlorophyll a concentration
to carbon biomass. At present, fluorometry and high-performance liquid chromatography (HPLC) havebeen widely used for the analysis of chlorophyll a in seawater. In this chapter, the methodology for thedetermination of chlorophyll a concentration in seawater by fluorometry is mainly introduced.
2. Sampling, filtration and pigment extraction
Seawater sampling is generally carried out by using a plastic bucket and/or water samplers. Because
algal pigments are highly photosensitive, it would be preferable to conduct further experimental
procedures under subdued light conditions after sampling. Before starting seawater filtration, seawater
volume must be measured correctly using a graduated cylinder or other apparatus. In general, glass-fiber
filters (e.g. Whatman® GF/F, nominal pore size 0.7 µm) with 25 or 47 mm in diameter are often used
for the seawater filtration. Also, to estimate cell sizes in phytoplankton community, membrane filterswith precise pore sizes (e.g. 20 µm, 2.0 µm, 0.2 µm) are utilized. Also, the membrane filters should be
tolerant for the organic solvents used for pigment extraction. For example, in the case that N,Ndimethylformamide (DMF) is applied for pigment extraction, polycarbonate track-etch membrane filters(e.g. Whatman® Nuclepore) are not recommended because of its intolerance to DMF. Therefore, in ourlaboratory, nylon membrane or polystyrene track-etch membrane filters (e.g. GVS Life Sciences) havebeen used for DMF pigment extraction. For the filtration volume, the required seawater could be around50–200 mL and 200–300 mL for coastal and oceanic waters, respectively. Vacuum filtration should bemade under ≤ 0.016 MPa (12 cm Hg) to prevent the cells from significant damages. After filtration, thefilters should be transferred into glass tubes or organic-solvent-tolerant vials containing the known
amount (5–10 mL) of DMF, 90% acetone (acetone : water = 90 : 10 in volume) or methanol. It is known
that DMF, which is often used in the field of oceanography in Japan, has higher chlorophyll a extraction
efficiency and less volatile at room temperature, and little produces break-down pigments during
extraction (Suzuki and Ishimaru, 1990). However, DMF is toxic, so operators must put DMF-tolerant
gloves and pay attention to ventilation in laboratory. In the case that the volume of organic solvent for
pigment extraction is minimized, seawater remained in the glass-fiber used for filtration may
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significantly affect the extraction volume. For example, 25 mm Whatman® GF/F filters can contain
200–250 µL of seawater, so the filters should be folded in half to keep the filtration side inside, and thenblotted with filter papers to remove the extra seawater. Algal pigments including chlorophyll a can beextracted in organic solvent for 24 h in the dark at –20°C.
3. Calibration curve
Once an authentic solid chlorophyll a standard from a manufacturer (e.g. Sigma-Aldrich Co. Ltd.)is dissolved in the organic solvent used for pigment extraction, its absorbance can be determined
spectrophotometrically. In the case of DMF, chlorophyll a absorbance at 750.0 nm and 663.8 nm aremeasured, and then the difference in absorbance between 663.8 nm and 750.0 nm can is regarded as thetrue chlorophyll a absorbance (hereafter A) assuming that the absorbance of chlorophyll a at 750 nm isnil. Using the Beer-Lambert law, chlorophyll a concentration (c) is expressed as the Equation 4.1:
c = A / ( ·l)(4.1)

where  is the absorption coefficient (L g-1 cm-1) for chlorophyll a, l is the pathlength (cm) of the solution.
Table 4.1 indicates the values of absorption coefficient for chlorophyll a in each organic solvent (DMF,
90% acetone, and methanol). Once the concentration of chlorophyll a is determined, the standard
solution should be diluted with the same organic solvent to make standards with different levels,
followed by the fluorometric analyses described below for examining the relationship between
chlorophyll a concentration and its fluorescent value (i.e. calibration curve).
4. Fluorometric analysis
Fluorometers specifically for the determination of chlorophyll a concentration are commerciallyavailable from some manufactures such as Turner Designs, Inc. If such a fluorometer is used, operators
should follow the manufacture’s protocol. In the case that a common fluorometer is utilized, theexcitation and emission wavelengths can be set at 436 nm and 680 nm, respectively, with a slit width
between 5–20 nm (cf. Welshmeyer, 1994). If higher sensitivity is required due to low chlorophyll aconcentration, the slit width needs to be expanded. However, such a broader slit width condition may
cause some errors due to the interference with chemical compounds other than chlorophyll a.
Prior to sample measurement, an appropriate volume of the organic solvent used for pigment
extraction is dispensed into a quartz cuvette for the determination of a blank value. After that the glassfiber filter, which was used for filtration, is removed from the organic solvent, fluorescence values ofeach sample can be measured. From the difference in fluorescence values between sample and blank,
the true sample fluorescence intensity can be determined. Then chlorophyll a concentration (C; g L-1) inseawater is estimated from the Equation 4.2:

C = x・v/V(4.2)

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where x is chlorophyll a concentration in the organic solvent used for pigment extraction, v and V areeach volume (L) of the organic solvent and seawater filtration, respectively. In general, the unit ofchlorophyll a concentration in seawater is µg L-1 (or mg m-3).

Table 4–1 Absorption coefficients of chlorophyll a in each solvent at specific wavelength.
Solvent

Wavelength(nm)

Absorption coefficient References(L g-1 cm-1)

DMF

663.8

88.74

Porra et al. (1989)

90% acetone

664.3

87.67

Jeffrey and Humphrey (1975)

Methanol

665.2

79.95

Porra et al. (1989)

5. High-performance liquid chromatography (HPLC) and ultra-high-performance liquid
chromatography (UHPLC)
Analytical procedures for the fluorometry described above is rather simple, and the technique canestimate chlorophyll a concentration with high sensitivity. However, this method may overestimate
chlorophyll a values due to the presence of chlorophyll breakdown compounds which have the same
florescence properties as the photosynthetic pigment and/or with chlorophyll b (Welshmeyer, 1994).
Therefore, to estimate chlorophyll a concentration more precisely, high-performance liquid
chromatography (HPLC) or ultra-high-performance liquid chromatography (UHPLC) need to be
employed. For the algal pigment analyses using HPLC, the methods of Zapata et al. (2000) or Van
Heukelem and Thomas (2001) have often been used. Recently, Jayaraman et al. (2011) and Sanz et al.
(2015) succeeded in the improvement of separation between divinyl and monovinyl forms ofchlorophylls using a C16-Amide column and a pentafluorophenyloctadecyl silica column, respectively.
The HPLC and UHPLC techniques allow us to analyze not only chlorophylls, but also carotenoids
simultaneously. The UHPLC systems recently developed are equipped with analytical columns withparticle sized less than 2 µm and instrumentation that is capable of delivering pressures above 40 MPa(up to ca. 130 MPa), therefore they can analyze algal pigments with high speed and high resolution(Guillarme and Veuthey, 2012). In general, it takes ca. 30 min or more to analyze algal pigments with
HPLC, whereas the UHPLC technique developed by Suzuki et al. (2015) can complete the separationsof chlorophylls and carotenoids from marine phytoplankton within 7 min with similar resolution as
conventional HPLC methods. Abundance and composition of phytoplankton assemblages in seawater
can be estimated with taxonomically unique algal pigments. The relative contributions of each
phytoplankton group at the class level to chlorophyll a concentration have often been calculated using
the factorization program CHEMTAX (Mackey et al., 1996) or multiple regression analysis (e.g. Suzuki
et al., 2002).
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References
Chisholm, S. W., R. J. Olson, E. R. Zettler, R. Goericke, J. B. Waterbury, and N. A. Welshmeyer (1988): A novel
free-living prochlorophyte abundant in the oceanic euphotic zone. Nature, 334, 340–343.
Guillarme, D. and J. -L. Veuthey (2012): UHPLC in Life Sciences. RSC Publishing, 447 pp.
Falkowski, P. G. and T. G. Owens (1980): Light–shade adaptation. Plant Physiol., 66, 592–595.
Harrison, P. J., H. L. Conway, R. W. Holmes, ad C. O. Davis (1977): Marine diatoms grown in chemostat undersilicate or ammonium limitation. III. Cellular chemical composition and morphology of Chaetoceros debilis,
Skeletonema costatum, and Thalassioisira gravida. Mar. Biol., 43, 19–31.
Jayaraman, S., M. L. Knuth, M. Cantwell, and A. Santos (2011): High performance liquid chromatographic
analysis of phytoplankton pigments using a C16-Amide column. J. Chromatogr. A, 1218, 3432–3438.
Jeffrey, S. W. and G. F. Humphrey (1975): New spectrophotometric equations for determining chlorophylls a, b,
c1 and c2 in their higher plants, algae and natural phytoplankton. Biochem. Physiol. Pflanzen, 167, 191–194.
Jeffrey, S. W., S. W. Wright, and M. Zapata (2011): Microalgal classes and their signature pigments, p. 3–77, In
Phytoplankton Pigments: Characterization, Chemotaxonomy, and Applications in Oceanography, edited by S.
Roy, C. A. Llewellyn, E. S. Egeland and G. Johnsen, Cambridge University Press, Cambridge.
Mackey, M. D., D. J. Mackey, H. W. Higgins, and S. W. Wright (1996): CHEMTAX – a program for estimatingclass abundances from chemical markers: application to HPLC measurements of phytoplankton. Mar. Ecol.
Prog. Ser., 144, 265–283.
Porra, R. J., W. A. Thomas, and P. E. Kriedemann (1989): Determination of accurate extinction coefficients andsimultaneous equations for assaying chlorophyll a and b extracted with four different solvents: verification of
the concentration of chlorophyll standards by atomic absorption spectroscopy. Biochim. Biophys. Acta, 975,
384–394.
Sanz, N., A. García-Blanco, A. Gavalás-Olea, P. Loures, and J. L. Garrido (2015): Phytoplankton pigment
biomarkers: HPLC separation using a pentafluorophenyloctadecyl silica column. Meth. Ecol. Evol., 6, 11991209.
Suzuki, K., C. Minami, H. Liu, and T. Saino (2002): Temporal and spatial patterns of chemotaxonomic algal
pigments in the subarctic Pacific and the Bering Sea during the early summer of 1999. Deep-Sea Res. II, 49,
5685–5704.
Suzuki, K., A. Kamimura, and S. B. Hooker (2015): Rapid and highly sensitive analysis of chlorophylls andcarotenoids from marine phytoplankton using ultra-high performance liquid chromatography (UHPLC) withthe first derivative spectrum chromatogram (FDSC) technique. Mar. Chem., 176, 96–109.
Suzuki, R. and T. Ishimaru (1990): An improved method for the determination of phytoplankton chlorophyll using
N,N-dimethylformamide. J. Oceanogr. Soc. Japan, 46, 190–194.
Van Heukelem, L. and C. S. Thomas (2001) Computer-assisted high-performance liquid chromatography method
development with applications to the isolation and analysis of phytoplankton pigments. J. Chromatogr. A, 910,
31–49.
Welshmeyer, N.A. (1994) Fluorometric analysis of chlorophyll a in the presence of chlorophyll b andpheopigments. Limnol. Oceanogr. 39, 1985–1992.

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Zapata, M., F. Rodoríguez, and J. L. Garrido (2000): Separation of chlorophylls and carotenoids from marine
phytoplankton: a new HPLC method using a reversed phase C8 column and pyridine-containing mobile phases.
Mar. Ecol. Prog. Ser., 195, 29–45.

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Direct Counting Methods of Prokaryote and Heterotrophic
Nanoflagellates by Epifluorescence Microscopy‫ۑ‬Taichi YOKOKAWA (Japan Agency for Marine-Earth Science and Technology, JAMSTEC)

Prokaryotes and heterotrophic nanoflagellates (HNF) are abundant in the aquatic environment andplay important roles in biogeochemical processes in the aquatic ecosystem (Konhauser, 2007; Madsen,
2008; Kirchman, 2008). A typical liter of water from the surface of a lake or ocean contains ~109prokaryotic cells and 105 HNF cells, depending on the environment (Kirchman 2012). Studying the
dynamics of the abundance and activities of microbes is important because microbes are the mostabundant organisms in aquatic environments and mediate many essential biogeochemical processes.
Methods for enumeration of aquatic microbes have been established and described in several papers
and books (e.g., Sherr et al. 1993; Turley 1993, Caron 2001; Sherr et al. 2001). It is recommended toread those references before starting your experiments. The methods described in this chapter and in thereferences are not appropriate for all purposes. Users must modify the method to suit their own purpose.
This chapter is composed of the following four sections:
1) Sampling2) Sample fixation
3) Staining, filtration, and producing sample slides4) Sample observation and enumeration
Procedures
1.

Sampling

Sampling apparatus
The sampling apparatus (bucket, bottle) should be washed and sterilized before collecting samples
to avoid any biological or chemical contamination. Rinsing with the sample water is also recommended
to avoid contamination. Other apparatuses for sampling (tubing, funnel) and sample bottles should also
be washed and sterilized before use. Use of a pre-washed, sterilized, and disposable plastic apparatus
for sampling and sample storage is convenient.
Sampling
Wear plastic laboratory gloves and use the apparatus described above during sampling to avoid
contamination. Store samples in a refrigerator (dark, 4°C) immediately following sampling, and preserve
the samples using a fixative as soon as possible. Long-term storage of samples without fixation may
result in growth or death of microbes and grazing of HNF on prokaryotes. Freezing of samples without
fixation is not recommended because the freeze–thaw process may disrupt microbial cells.
2.

Sample fixation
Fixation should be performed immediately following sampling. Prokaryote samples (1–20 mL)should be preserved in neutral-buffered formalin solution (final concentration, 1%) that has been passed
through a 0.2 Pm filter. Samples should be refrigerated (4°C) until being subjected to filtration (~12 h).
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HNF samples (1–100 mL) should be preserved in glutaraldehyde solution (final concentration, 1%).
Samples should be refrigerated (4°C) until being subjected to filtration (~12 h). The type of fixative andits final concentration should be selected according to the objective, particularly for molecular biology
techniques.
3.

Staining, filtration, and producing sample slides

Cell staining
Both prokaryote and HNF cells must be stained with a fluorochrome for enumeration using aepifluorescence microscope because these cells do not auto-fluoresce. Cells that exhibit autofluorescence (those containing chlorophyll a, phycoerythrin, phycocyanin, bacteriochlorophyll, etc.) canbe detected using an epifluorescence microscope without staining.
For prokaryotic cells, fluorochromes that bind to DNA—such as acridine orange (AO, Hobbie et al.,1977), 4’6-diamidino-2-phenylidole (DAPI, Porter and Feig, 1980), and SYBR Green I (Marie et al.,1997)—are generally used (Sherr et al. 2001). Fluorochromes that bind to protein are also used forenumeration of microbial cells. For precise determination of bacterial cell size, use of a protein-binding
fluorochrome is more appropriate (Straza et al. 2009).
For HNF cells, fluorochromes that bind to DNA, such as AO and DAPI, are generally used (Sherret al. 1993). Double-staining with a DNA- and protein-binding fluorochrome is also used forenumeration of HNF cells (Fukuda et al. 2007).
Each fluorochrome has specific excitation/emission wavelengths (Table 1). Optical filter sets foreach fluorochrome must be used. The fluorochrome should be selected depending on the objectives ofthe experiment. DAPI is generally used for visualization of prokaryotes, whereas FITC is used for HNFs.
Staining of prokaryotic cells with DAPI and of HNF cells with FITC are described below.
Prokaryotic cell staining
Add DAPI solution to the sample at a final concentration of 1 Pg mL-1, followed by storage in thedark for 5–10 min. Large-volume samples (> 5 mL) should be reduced to 2 mL using a filtration funnel(to reduce the amount of DAPI required) and then stained with DAPI (final concentration, 1 Pg mL-1)
in the dark (cover the funnel with aluminum foil) for 5–10 min. After staining, the remaining sample
should be filtered.
HNF cell staining
Reduce the sample volume to 2 mL using the filtration funnel, and then release the vacuum. Add
FITC solution to the sample at a final concentration of 0.4 mg mL-1, and then incubate the sample in thedark for 5–10 min. After the staining period, rinse the funnel and filter twice using a few milliliters of
0.1 M sodium carbonate buffer (pH 9.5).
Sample filtration
The filtration apparatus should be washed with 0.2Pm-filtered (e.g., ADVANTEC, 25AS020AS)
deionized water before use and between each sample.
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Place a 0.45 Pm cellulose membrane backing filter (Millipore, HAWP02500) onto a 25 mm filtration
bottom (note: this backing filter is to spread cells evenly on the filter; the same backing filter can beused for multiple samples; replace daily). Soak with a few drops of 0.2 Pm-filtered deionized water.
Place a 0.2 Pm polycarbonate membrane filter or 0.8 Pm polycarbonate membrane filter for prokaryotesand HNF, respectively, onto the wetted backing filter. Place the filtration funnel on top of the filter. For
enumeration of prokaryote cells, a filter with an effective diameter (16–25 mm) is appropriate. For
enumeration of HNF cells, a filter with an effective diameter of 4 mm is appropriate (a smaller filter
area provides higher concentration efficiency]). Use forceps to handle filters, and try not to touch thefilter area.
For prokaryotes, filter an aliquot of DAPI-stained sample through a 0.2 Pm membrane filter. For
HNFs, filter an aliquot of fixed sample through a 0.8 Pm membrane filter. The sample volume requiredis dependent upon the cell concentration. A maximum vacuum of 80 mmHg is appropriate for filtration
to avoid damage to cells and ensure their random distribution. Rinse with a few milliliters of 0.2 Pmfiltered deionized water for prokaryotes or a few milliliters of 0.1 M sodium carbonate buffer for HNF.
With the vacuum on, carefully remove the membrane filter from the underlying backing filter. Proceed
to the next step, “Slide preparation,” immediately.
Slide preparation
For prokaryotic cells, place the filter onto a slide and place immersion oil (~10 PL) on the center ofthe filter. Mount a new coverslip on top of the filter and gently press down until the oil moves out to theedge of the filter and forms a seal. For HNF cells, use FA mounting fluid (pH 9.0–9.6) instead of
immersion oil.
4.

Sample observation and enumeration

Observation
Prepare the optical filters appropriate for the fluorochrome (Table 1). Samples are visualized using
a 100u oil immersion objective and 10u eyepiece. Prokaryotic cells are 0.2–2.0 Pm in length and brightblue-white in color. You may distinguish bacilli, cocci, and spirilli among prokaryotic cells. Plate 4 in
Pernthaler et al. (2001) shows a representative image of a prokaryotic cell. HNF cells are 2–20 Pm in
length and fit into a small quadrant of squared graticule. You may observe flagella attached to the cells.
Figure 3 in Sherr et al. (1993) and Figure 7.1 in Kirchman (2012) show several representative imagesof HNF cells.
Table 1. Fluorochrome characteristics.
Fluorochrome

Excitation peak (nm)Emission peak (nm)

AO

490

530, 640

DAPI

372

456

FITC

490

520

SYBR Green I

494

521

SYPRO Ruby

280

610

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Enumeration
Randomly choose 10 large quadrants (100 u 100 Pm) and count the cells in each. Thirty to fifty
cells per large quadrant are appropriate for counting. If the cell density is outwith this range, the sample
volume should be adjusted appropriately. Counting errors and variations of this method are described in
Kirchman (1993).
Calculate prokaryotic and HNF cell concentrations as follows:
Cells mL-1 = [SC u CF] / V,
where SC is the mean sample count/quadrant, CF is the effective filter area/quadrant area, and V isthe volume of preserved sample (not including the fixative volume).
Biomass estimates of prokaryotes and HNF are convenient for comparing the carbon budget to othermicrobial groups or prokaryotes and HNF in other environments. Two methods can be used to convert
cell abundance to carbon biomass. One is to convert cell volume to carbon content per cell (Norland
1993), and the other is using a conversion factor (e.g., 20 fg of C per cell, Fukuda et al., 1998). For
calculation of HNF biomass, please see Chapter 6 of this guideline.
It should be noted that the fixatives and fluorochromes described here could cause personal injury
and health problems. Appropriate protective equipment (e.g., protective eyewear, gloves, laboratory coat,etc.) should be worn and procedures conducted under appropriate laboratory conditions (e.g., clean
bench and fume food).
The methods described here are appropriate for current studies but may not be in the future. Moreappropriate fluorochromes, more efficient methods of concentrating cells, or more convenient
enumeration techniques may be developed. The enumeration methods should be updated as appropriate.
Cells have been enumerated by flow cytometry (described in the next section) in recent studies.
Materials required
Equipment and Supplies
Microscope: Epifluorescence microscope with a 100 W mercury lamp, a 100u oil immersion
objective, and an ocular grid of 10 u 10 squares.
Filtration apparatus (for prokaryotes): apparatus fit for 25 mm ࢥ filters (e.g., ADVANTEC filter
manifold KG25 or Hoefer Ten-Place Filtration Manifold FH225V).
Filtration apparatus (for HNF): apparatus fit for 25 mm ࢥ filters with a small effective filter area
(e.g., ADVANTEC filter manifold KGS-04)
Also, 0.2 Pm pore size, 25 mm polycarbonate membrane filters (for prokaryotes), and 0.8 Pm poresize, 25 mm polycarbonate membrane filters (for HNF). Black-stained filters of those types are usefulfor reducing strong background intensity (e.g., ADVANTEC polycarbonate filter K020N025A).
Backing filter: 0.45 Pm pore-size, 25 mm cellulose membrane filter
Vacuum pump
Glass slides and cover slips
Immersion oil and FA mounting fluid (Vmrd, Inc.)
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Solutions
DAPI stock solution, 0.5 mg mL-1. Dissolve 10 mg DAPI in 20 mL filtered distilled water. Dispense
0.5 mL aliquots of the DAPI stock solution into plastic vials and store at -20°C.
FITC staining solution
0.25 ml 0.5 M sodium carbonate buffer (pH 9.5)
1.1 mL 0.01 M potassium phosphate buffer (pH 7.2)
1.1 mL 0.85% sodium chloride
1.0 mg FITC
References
Caron, D. A. (2001): Chapter 15, Protistan herbivory and Bacteriovory, pp. 289–316. In Methods in
Microbiology, volume 30, edited by J. H. Paul, Academic Press.
Fukuda, H., R. Sohrin, T. Nagata, and I. Koike (2007): Size distribution and biomass of nanoflagellates in mesoand bathypelagic layers of the subarctic Pacific. Aquat. Microb. Ecol. 46, 203–207.
Hobbie, J. E., R. J. Daley, and S. Jasper (1977): Use of nucleopore filters for counting bacteria by fluorescencemicroscopy. Appl. Environ. Microbiol. 3, 1225–1228.
Kirchman, D. L. (1993): Chapter 14, Statistical analysis of direct counts of microbial abundance, pp. 117–120.
In Handbook of Methods in Aquatic Microbial Ecology, edited by P. F. Kemp, R. F. Sherr, E. B. Sherr and J.
J. Cole, Lewis Publisher.
Kirchman, D. L. (2008): Microbial Ecology of the Oceans, 2nd edition. Wiley.
Kirchman, D. L. (2012): Processes in Microbial Ecology. Oxford.
Konhauser, K (2007): Introduction to Geomicrobiology. Blackwell Publishing.
Madsen, E. L. (2008): Environmental Microbiology. Blackwell Publishing.
Marie, D., F. Partensky, S. Jaquet, and D. Vaulot (1997): Enumeration and cell cycle analysis of natural
populations of marine picoplankton by flow cytometry using the nucleic acid stain SYBR Green I. Appl.
Environ. Microbiol. 63, 186–193.
Pernthaler, J., F-O Glöckner, W Schönhuber, and R. Amann (2001): Chapter 11, Fluorescence in situ
hybridization with rRNA-targeted oligonucleotide probes, pp. 207–226. In Methods in Microbiology,
volume 30, edited by J. H. Paul, Academic Press.
Porter, K. G. and Y. S. Feig (1980): The use of DAPI for identifying and counting aquatic microflora. Limnol.
Oceanogr. 25, 943–948.
Sherr, B., E. Sherr, and P del Giorgio (2001): Chapter 8, Enumeration of total and highly active bacteria, pp.
129–159. In Methods in Microbiology, volume 30, edited by J. H. Paul, Academic Press.
Sherr, E. B., D. A. Caron, and B. F. Sherr (1993): Chapter 26, Staining of heterotrophic protists for visualization
via epifluorescence microscopy, pp. 213–228. In Handbook of Methods in Aquatic Microbial Ecology,
edited by P. F. Kemp, R. F. Sherr, E. B. Sherr and J. J. Cole, Lewis Publisher.
Straza, T. R. A., M. T. Cottrell, H. W. Ducklow, and D. L. Kirchman (2009): Geographic and phylogenetic
variation in bacterial biovolume as revealed by protein and nucleic acid staining. Appl. Environ. Microbiol.
75, 4028–4034.

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Turley, C. M. (1993): Chapter 18, Direct estimates of bacterial numbers in seawater samples without incurring
cell loss due to sample storage, pp. 143–148. In Handbook of Methods in Aquatic Microbial Ecology, editedby P. F. Kemp, R. F. Sherr, E. B. Sherr and J. J. Cole, Lewis Publisher.

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Enumeration of prokaryotes by flow cytometry‫ۑ‬Mitsuhide SATO 䠄Graduate School of Agricultural and Life Sciences, the University of Tokyo䠅

1.

Instrument and reagents
࣭A flow cytometer and its ancillaries
࣭Black plastic bottles of volume > 50 mL
࣭Micropipettes (1 mL and 10 ȝL)
࣭Standard fluorescent bead suspension (with a diameter of ~1 ȝm)࣭SYBR Green I (or SYBR Gold) solution
࣭A vortex mixer
For sample fixation
࣭Glutaraldehyde or paraformaldehyde solution
࣭Disc filters (with a pore size < 0.2 ȝm) and a syringe࣭Microdispenser
࣭Cryovials and canes
࣭A dry shipper࣭A deep freezer
To measure samples onboard, a flow cytometer with an optical system that can be readily adjusted

by a user is necessary. For oceanographic requirements, an argon ion laser or a solid laser that can emit
blue light is recommended, because it can excite chlorophyll, phycoerythrin and various artificial
fluorescent probes including SYBR Green I and SYBR Gold. Light channels should include forward
scatter (FSC), side scatter (SSC), green fluorescence (FL1) for fluorescent probes, orange fluorescence(FL2) for phycoerythrin and red fluorescence (FL3) for chlorophyll. The cytometer should be installed
on a vibration isolation table in a dry laboratory, and its power should be supplied by a noise-free source.
Before and after measurements, instrumental settings should be checked using standard fluorescentbeads. Before sampling, plastic bottles should be soaked in detergent and rinsed well with distilled water.
The bottles must be rinsed immediately after use, and air-dried. The standard bead suspension should
be diluted depending on the intended use and stored in a refrigerator. The concentration should bemeasured using an epifluorescence microscope. SYBR Green I or SYBR Gold should be stored in afreezer after being diluted 100 times.
2.

Sampling and measurement
Seawater can be dispensed directly into black plastic bottles or through silicon tubing from water

samplers. The bottles must not be subjected to direct sunlight, to avoid temperature change. A cooler isuseful to minimize the temperature change until further analysis.
Fluorescent beads are added to the sample before analysis for the following two reasons. The first is
to serve as a standard for the flow rate. The flow rate of a flow cytometer is unstable onboard, except
when installed with a syringe pump, which can serve a sample at a controlled rate, as it is affected by
the ship’s motion and engine vibration. To know an exact flow rate, a bead suspension with a known
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G4052EN-2

particle concentration is added. The second is to serve as a standard of scatter and fluorescenceintensities. The light intensities measured by a cytometer can be affected by machine sensitivity,
configuration of optical systems, life of the laser, and run length. To compare the values among different
samples, they should be normalized to those of the standard beads. The intensity of forward and side
scatters is essential to estimate cell size (Ackleson and Spinrad, 1988). The concentration of the beads
added must not be too low or too high, relative to the total particle concentration in the sample.
For sheath fluid, either commercially available fluid, filtered seawater (< 0.2 ȝm), or Milli-Q water
can be used, although each of the three has advantages and disadvantages. Commercially available fluid
can prevent adhesion of microbes to the tubing inner wall; however, it costs more than the other twoalternatives. Milli-Q water is the most economical, and does not induce biofouling. Filtered seawater isadvantageous in estimating cell size, because it has the same refractive index as the samples (Cucci andSieracki 2003), although it frequently induces biofouling. Any of the three above-mentioned materials
can be used as sheath fluid, depending on the purpose of the measurement. After using filtered seawater
as sheath fluid, it is necessary to clean the tubing vigorously using commercially available sheath fluidor detergent diluted with Milli-Q water. Sonication treatment of sheath fluid may be effective indecreasing noise, by removing the microbubbles present in it.
For enumeration of phytoplankton, which requires no staining procedures, the appropriate volumeof seawater is poured into a sample cell. The sample should be measured using FL3 as a trigger
parameter, while arranging the gains so that targeted populations are properly captured on FL2-FL3 andFL3-FSC (or SSC) cytograms. The flow rate should be properly set, with a tradeoff of efficiency andsensitivity or precision. When focusing on Prochlorococcus, which has an extremely faintautofluorescence, large eukaryotic phytoplankton or nano-sized cyanobacteria are sometimes omitted
from the detection range. When this occurs, the same sample should be measured twice using different
settings. For detailed processes of categorization of different phytoplankton populations on cytograms,
see Marie et al., (1999) or Sato et al., (2010).
For enumeration of heterotrophic prokaryotes, which include bacteria and archaea, fluorescentprobes for nucleic acids are generally used, among which SYBR Green I (Marie et al., 1997) is the mostwidely used, followed by SYTO 13 or PicoGreen. SYBR Gold can be used as an alternative to them(Patel et al., 2007). When added at high concentrations, the fluorescent probe can stain unfixed marineprokaryotes efficiently for detection by flow cytometry (Kamiya et al., 2007). Ten minutes before
measurement, 1 mL of seawater sample should be mixed with 10 ȝL of SYBR Green I working solution
and vortexed. FL1 is used for as trigger parameter. The cluster of prokaryotes that appears on an FL1FSC (or SSC) cytogram includes the cyanobacterium Prochlorococcus with faint chlorophyll
fluorescence; it is required to correct for it (Sieracki et al., 1995). On the cytogram, more than two
clusters with different FL1 intensities are sometimes observed, which possibly reflect their ecologicaldifference (Gasol and del Giorgio, 2000). Differentiation of the clusters becomes easier when membrane
permeability is enhanced by chemical fixation (Kamiya et al., 2007).
After measurement, tubing should be rinsed repeatedly, which is followed by an appropriate
shutdown procedure. Because the residual stains in the tubing may cause noise, the use of a surfactant
detergent is recommended after using a staining reagent. The machine operating time should be recorded
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for quality control of the laser.
3.

Sample preservation
Owing to the limitation of space or time, samples collected for flow cytometry are sometimes

preserved. Among the various preservation methods available, most include chemical fixation byaldehyde, snap freezing in liquid nitrogen, and storage at í80 °C. Glutaraldehyde, paraformaldehyde,
or a combination of the two is widely used as fixative. Since preservation efficiency depends on species
composition, its physiological status and the method used (Vaulot et al., 1989; Trousselier et al., 1995;
Sato et al., 2007), the optimum method applicable to every marine microbial community is yet to beestablished. Here, I introduce a simple preservation method using glutaraldehyde, which has highfixation efficiency.
Prior to sampling, 20% glutaraldehyde solution (for electron microscopy) should be filtered througha disc filter by using a syringe to remove particles that may cause noise. Using a micropipette, dispense
the samples into cryovials (~5 mL), and then add the glutaraldehyde solution at a final concentration of
1% by using a microdispenser. Tightly close the lids, mix the solution within the cryovials by gentle
shaking, and leave them still for 10 min in a refrigerator before snap-freezing in liquid nitrogen. If thedry shipper is not large enough to contain all samples, some samples can be stored in a deep freezer after
snap freezing. For transportation, dry ice is recommended to maintain the lowest possible temperature.
The preserved samples should be thawed in running water just before measurement. Ensure that there is
no ice remaining in the samples. Refreezing of the samples is not recommended. Recently, it wasreported that glutaraldehyde fixation with the addition of small amounts of surfactant can greatly
improve cell preservation (Marie et al., 2014).
References
Ackleson, S. G. and R. W. Spinrad (1988): Size and refractive index of individual marine particles: a flow
cytometric approach. Appl. Opt., 27, 1270-1277.
Cucci, T. L. and M.E. Sieracki (2001): Effects of mismatched refractive indices in aquatic flow cytometry.
Cytometry, 44, 173-178.
Gasol, J. M. and P. A. del Giorgio (2000): Using flow cytometry for counting natural planktonic bacteria andunderstanding the structure of planktonic bacterial communities. Sci. Mar., 64: 197-224.
Kamiya, E., S. Izumiyama, M. Nishimura, J. G. Mitchell, and K. Kogure (2007): Effects of fixation and storage
on flow cytometric analysis of marine bacteria. J. Oceanogra., 63: 101-112.
Marie, D., F. Partensky, S. Jacquet, and D. Vaulot (1997): Enumeration and cell cycle analysis of natural
populations of marine picoplankton by flow cytometry using the nucleic acid strain SYBR Green I. Appl.
Environ. Microbiol., 63: 186-193.
Marie, D., F. Partensky, D. Vaulot, S. Brussaard (1999): Enumeration of phytoplankton, bacteria, and viruses inmarine samples. In Current Protocols in Cytometry Supplement 10, ed. by J. P. Robinson, Z. Darzynkiewicz,
P. N. Dean, A. Orfao, P. S. Rabinovitch, C. C. Stewart, H. J. Tanke, L. L. Wheeless and L. G. Dressier,Wiley, New York.

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Marie, D., F. Rigaut-Jalabert, and D. Vaulot (2014): An improved protocol for flow cytometry analysis ofphytoplankton cultures and natural samples. Cytometry A, 85: 962-968.
Patel, A., R. T. Noble, J. A. Steele, M. S. Schwalbach, I. Hewson, and J. A. Fuhrman (2007): Virus andprokaryote enumeration from planktonic aquatic environments by epifluorescence microscopy with SYBRGreen I. Nature Protocols, 2: 269–276.
Sato, M., S. Takeda, and K. Furuya (2006): Effects of long-term sample preservation on flow cytometric analysis
of natural populations of pico- and nanophytoplankton. J. Oceanogr., 62: 903-908.
Sato, M., F. Hashihama, S. Kitajima, S. Takeda, and K. Furuya (2010): Distribution of nano-sized
Cyanobacteria in the western and central Pacific Ocean, Aquat. Microb. Ecol., 59, 273-282.
Sieracki, M. E., E. M. Haugen, and T. L. Cucci (1995): Overestimation of heterotrophic bacteria in the Sargasso
Sea: direct evidence by flow and imaging cytometry. Deep-Sea Res. I, 42: 1399-1409.
Troussellier, M., C. Courties and S. Zettelmaier (1995): Flow cytometric analysis of coastal lagoon
bacterioplankton and picophytoplankton: fixation and storage effects. Est. Coast. Shelf Sci., 40, 621-633.
Vaulot, D., C. Courties and F. Partensky (1989): A simple method to preserve oceanic phytoplankton for flow
cytometric analyses. Cytometry 10: 629-635.

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Primary Production
Koji Suzuki (Hokkaido University)

1. Introduction
Production of organic matter through phytoplankton photosynthesis (i.e. primary production) can be
simply expressed as Equation 7.1:
Photosynthesis
6CO2 + 6H2O

C6H12O6 + 6O2(7.1)

Respiration
Global annual net primary production (gross primary production minus respiration) by
phytoplankton on the basis of carbon is estimated to be ca. 50 × 1015 g C, which is roughly equivalent
to those produced by terrestrial plants (Raven, 2009). As field techniques for determining the primary
production by phytoplankton, carbon fixation, oxygen evolution and chlorophyll fluorescencemeasurements have been used (Marra, 2002). Here I introduce the 13C technique (Hama et al., 1983),
because this method has been widely used in Japan for the determination of primary production bymarine phytoplankton. For the 13C technique which is one of the carbon fixation methods, a small
amount of sodium bicarbonate labelled with 13C (NaH13CO3) is enriched into seawater sample, followed
by incubation for a certain time period, and measure the fixed organic carbon labelled with 13C toestimate primary productivity (i.e. primary production rate). For the measurements of primary
production by marine phytoplankton, the higher-sensitive, radioisotope labelled 14C technique has been
widely used in the world. However, in some countries including Japan where the use of radioisotopes
outside has been severely limited, the 13C method would be in use more conveniently. A good agreement
between 14C- and 13C-based primary productivity has been observed (Hama et al., 1983). Marra (2009)
pointed out that 14C uptake over daytime (dawn to dusk) periods estimates net primary production,
whereas 24-h 14C assimilation approximates daily net community production (i.e. net primary
production minus heterotrophic respiration) based on the O2 method, but the former is perhaps slightly
higher than the latter.
2. Sample collection and incubation
Seawater samples are generally collected by using water samplers (e.g. Niskin bottles, which are
pre-washed with neutral detergent, followed by diluted hydrochloric acid and pure water to avoid any
metal contamination). First seawater for the determination of total dissolved inorganic carbon (DIC)
concentrations should be transferred into glass bottles without air bubbles. To suspend any biologicalactivity, saturated mercury chloride (II) solution (0.02% (in volume) at the final concentration) is added
to each DIC bottle. The sample bottles are closed tightly and then stored at room temperature. The DIC
concentrations can be determined by coulometry, pH sensor, and so on (see Vol. 3, Chapter 4) soon after
the sample collection. As incubation bottles for primary production measurement, more than four
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polycarbonate bottles, which are pre-washed by neutral detergent and 10% (in volume) hydrochloric
acid, with ca. 250 and 500–1000 ml for coastal and oceanic waters, respectively, should be prepared,
and the two are for light bottles and one is for dark bottle (covered with black tape, etc.). One can beprepared for the determination of particulate inorganic carbon (PIC) concentrations before the additionof 13C. Size of the incubation bottles used for primary production measurement is dependent on theamount of organic matter in seawater, but larger bottles would be better to minimize the physical effectof bottle walls (i.e. bottle effect). A certain amount of seawater is filled into each incubation bottle.
Furthermore, a small amount of NaH13CO3 solution is added to the light and dark bottles to become ca.
10% in terms of 13C abundance. For reference, DIC concentrations in surface oceanic waters are
generally ca. 2 mmol kg-1 (corresponding to 24 mg C L-1; Zeebe and Wolf-Gladrow, 2001). However,the DIC concentrations can vary in other marine environments, therefore approximate DIC levels shouldbe estimated before experiments. Incubation can be conducted from a few hours to 1 day using in situ
or simulated in situ methods. For the in situ technique, the seawater samples collected from surface
layers of the water column are dispensed into incubation bottles, followed by 13C addition, returned thebottles to the sampling layers using a moored system, and incubated for a certain time period. For thesimulated in situ method, on the other hand, the samples are incubated in a water tank on land or on
board for a certain period by simulating the sampling site environments (light and temperature) using
temperature controllers, neutral light screen and/or filters. Immediately after the start of incubation,
seawater samples for the determination of natural 13C abundance of particulate organic carbon (POC)(i.e. before 13C enrichment) should be filtered with pre-combusted (450°C, ≥ 4 h) glass-fiber filter (e.g.
25 mm Whatman GF/F) soon (in the case of vacuum filtration, the pressure should be < 0.016 MPa).
The filter combustion can be made in an electric furnace to remove organic carbon attached to the filter.
The sample filters obtained are stored in a freezer at < –20°C. After incubation, seawater from the lightand dark bottles also should be filtered soon and the filters obtained can be stored in the same manner
as above.
3. Sample pre-treatment
The frozen filters stored are melted at room temperature and exposed to the vapor from hydrochloric
acid in order to remove PIC from them. After the procedures, the filters should be completely dried in a
desiccator.
4. Sample pre-treatment
The concentration and 13C abundance of POC are determined with an elemental analyzer and a mass
spectrometer or an infrared spectrometer, respectively. For the POC concentration, refer to the text inVol. 4, Chapter 1. Also, for the determination of 13C abundance, follow the manufacture’s manual.
To estimate the primary production by phytoplankton using 13C method, the following mass balance
equation of 13C abundance before and after incubation can be set:
ais ・POC=

ans ・ (POC – ΔPOC)+

aic ・ΔPOC

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where ais and ans are 13C abundance (13C atom%) in POC after incubation and that before 13C addition,
respectively. POC is the concentration of POC after incubation. ΔPOC

is the concentration of POC

increased during incubation. By solving the Equation 7.2 for ΔPOC, the following Equation 7.3 can beobtained:
ΔPOC=

POC ・ (ais – ans) / ( aic – ans)

（7.3）

Primary productivity (i.e. primary production rate; P) can be estimated by dividing ΔPOC in the
Equation 7.3 by the time period of incubation T and these are multiplied by the fractionation factor of13

C (=1.025; Hama et al., 1983).
P = ΔPOC ・ f / T= [POC ・ (ais – ans)] ・ f / [( ais – ans)・T]（7.4）

For the estimates of P, the mean and its standard deviation can be calculated using the values fromlight and dark bottles. Also, for the correction of non-photosynthetic carbon fixation and the adsorptionof 13C, values from light bottles should be subtracted from those from dark bottles.
Values of P normalized by chlorophyll a concentration (see Vol. 4, Chapter 4) have been used for an
index of phytoplankton-abundance specific primary productivity.
References
Hama, T., T. Miyazaki, Y. Ogawa, T. Iwakuma, M. Takahashi, A. Otsuki, S. Ichimura (1983): Measurement ofphotosynthetic production of a marine phytoplankton population using a stable 13C isotope. Mar. Biol., 73, 31–
36.
Marra, J. (2002): Chapter 4, Approaches to the measurement of plankton production, p. 78–108, In Phytoplankton
Productivity: Carbon Assimilation in Marine and Freshwater Ecosystems, edited by P. J. le B. Williams, D. N.
Thomas and C. S. Reynolds, Blackwell Science, Oxford.
Marra, J. (2009): Net and gross productivity: weighing in with 14C. Aquat. Microb. Ecol. 56, 123–131.
Raven, J. A. (2009): Volume 4, Primary production processes, p. 585–589. In Encyclopeia of Ocean Sciences, 2nd
Edition, edited by, J. H. Steele, S. A. Thorpe and K. K. Turekian, Academic Press, London.
Zeebe, R. E., Wolf-Gladrow, D. (2001) CO2 in Seawater: Equilibrium, Kinetics, Isotopes, Elsevier, 346 pp.

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Seabed sediment sampling‫ۑ‬Hisashi NARITA (Tokai University)/ Shigeyoshi OTOSAKA (Japan Atomic Energy Agency)

Seabed sediments are classified into coastal, hemipelagic, and pelagic sediments.

The

sedimentation rate, grain size, and chemical and mineralogical characteristics of these sediments
varygreatly depending on the cycling of materials in the marine environment and sedimentary
environments of the respective region. The collection and analysis of marine sediments clarifies thecharacteristics of this cycling allowing dtermination of the source material deposited on the seafloor
and understanding the nature of primary production in the surface layer. In addition, the information
recorded in the seabed sediments serves as historical markers to unravel past regional and globalchanges in environment, circulation, and climate.
1. Selection of sampling location
Collection of seabed sediment is typically referred to as “bottom sampling”.

A rope or cable witha bottom sampler attached is lowered from the ship to the seabed is lowered from the ship to theseabed. Because the sedimentation process of various seafloor materials is greatly influenced by the
topography of the site, it is necessary to carefully select sampling points considering the surrounding
topography and the bottom environment.

Abundant topographical data are available for the coastal

area, including much of the continental shelf.

Chart symbols/abbreviations (R, S, M, Sh, etc.) canbe used as approximate information on the seafloor, where R, S, M, and Sh indicate rock, sand, mud,and shell, respectively. However, detailed topographical and sedimentary information required todetermine sampling points is generally limited in much of the open ocean.

Therefore, whencollecting seabed sediments, especially several meters of core samples, it is recommended to obtain
information on bottom sediments and topographical information before selecting sampling points.
To acquire topographic information of the seabed, systematic observation using either aprecision depth recorder (PDR) or multi-beam echo sounder is necessary. To understand the natureof the underlying sediments, a sub-bottom profiler is often utilized. This system transmits a ~3.5
kHz sound pulse from the research vessel and receives reflections from the seabed and underlying
sediments. Based on this system, it is possible to obtain acoustic images of geological profiles up to
several tens of meters below the seafloor with high resolution.
2. Sediment samplers“Sediment sampling” means to collect sediments, rocks and benthic organisms from seabedsediments. A variety of bottom samplers have been developed according to purpose and sedimenttypes. They are roughly classified into dredges, grab samplers, and core samplers. A steel

cable

generally used deploy this heavy equipment. To confirm that the sampler has landed on the seabedor that the sample enters the sampler, a tensiometer is commonly used to monitor the tension of thecable.

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2-1 Dredge samplers

A dredge sampler consists of a cylinder or a box-shaped, steel bucket.

Sediments, rocks, andbenthos are collected by towing this device on the seafloor,. To tow a dredge sampler, the cable
length needs to be longer than the water depth.
may be damaged if it is extended too long.

However, care should be taken because the cable

Because this device dredges on the seafloor for a given

distance, the obtained sediments will show an average composition in certain areas.

For this reason,

this devise is not suitable for the collection of samples at a fixed point on the seafloor. In addition,
samples may be disturbed or decomposed during the dredging, and some samples may selectively flowout when the sampler is retrieved on board the ship.
2-2 Grab samplers

The grab sampler collects sediment samples by rotating and closing two opposed semicylindricalbuckets.

It collects the upper (~10 cm) sediments with minimal disturbance across a relatively widesurface area, even in sand or gravel. The trigger for closing the buckets may be activated by either ashock upon landing on the seafloor (Smith-McIntyre sampler) or by operating a trigger with a“messenger” weight after landing (Ekman-Burge sampler).

Both samplers can be used to precisely

identify the sampling point and are suitable for understanding the inventory of chemical substances
and the standing stock of the benthic organisms in the sediment because of collection along a constantsurface area.

Because they are compact and lightweight, grab samplers are also widely used forsampling by small boats in shallow water.
An OKEAN-type grab sampler using a balance as a bottom trigger is used for sedimentcollection in the deep sea. Although the sample is sometimes disturbed by the operation wire used
for closing the bucket, it can collect coarse sediments, such as gravel, because of its heavy weight.
The box corer is an improved type of grab sampler, which was designed to collect sediments
to a depth of approximately several tens of centimeters without disturbance. It consists of a core box
with a 30 cm or 50 cm cube coupled to a core cutter (called a spade) that functions as a bottom coverfor the penetrated core box. In addition to being capable of collecting undisturbed surface sediments,
it is also suitable for collecting a large volume of sediment.

As necessary, core samples can beobtained by penetrating subcores into the core box after retrieval of the box corer on board.
Therefore, the box corer is sometimes categorized as a core sampler rather than a grab sampler.
2-3 Core samplers

The core sampler is a device that penetrates a barrel (cylindrical pipe) vertically into the seabed andcollects sediments with a length of several tens of cm or more.
include gravity, vibration, push-in corers.
observations.

Devices used to penetrate the barrel

The gravity corer is widely used for oceanographic

It simply penetrates the barrel into the sediment by its own weight.

A piston corer

prevents the loss of samples based on the negative pressure in the piston attached to the barrel.

Bothgravity and piston corers can collect samples from 1 m to several tens of meters but are not suitable tocollect sand and gravel. To collect sediments in shallow water, other types of core sampler, such as
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the vibration corer and push-in-type thin wall sampler, are used. These corers can also collect sandy
sediments and the disturbance of the sample is relatively small.
Recently, multiple (multi-barrel) corers with several polycarbonate pipes with a diameter of
60 to 80 mm and a length of 600 mm are widely used for the collection of surface sediments with alength of about 300 mm.

The multiple corer can slowly penetrate cores into sediment by its own

weight, with the speed of 5 mm s-1 or less, by regulating the amount of seawater discharged from thecylinder at the center of the main frame of the corer (Barnett et al., 1984). To complete the core
penetration based on mechanical characteristics, it is necessary to wait for 1.5~2 min in case of muddy
sediments and > 1~2 min for sandy sediments after the corer landed on the seabed.

In addition, it isnecessary to let out the cable for a few meters to a few tens of meters after the landing of the corer andmonitor tension to confirm that the corer is not lifted during the waiting time.

In case it is expectedthat the cable will experience tension during the waiting time due to the movement of the boat, thewire should be extended a few more meters than needed. The advantage of this device is that it canalso collect the overlying water above the seafloor without disturbing the sediment-water interface(Shirayama and Fukushima, 1994).
References
Barnett, P.R.O, J. Watson and D. Connelly (1984): A multiple corer for taking virtually undisturbed samples
from shelf, bathyal and abyssal sediments. Oceanologica Acta. 7 (4), 399-408.
Shirayama, Y. and T. Fukushima (1994): Comparisons of deep-sea sediments and overlying water collectedusing Multiple Corer and Box Corer. Journal of Oceanography. 51, 75-82.

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Physical properties of sediment(water content, bulk density and porosity)○Hisashi NARITA (Tokai University) /Shigeyoshi OTOSAKA (Japan Atomic Energy Agency)

Parameters reflecting the physical properties of seabed sediments include water content, porosity,and dry bulk density.

In particular, the water content and porosity can be measured relatively easily.

These parameters are related to the composition, average density, or the particle size of the sediments(Meade, 1966, Nafe and Drake, 1957). Therefore, the water content and porosity are effective
primary information on the sedimentation process and composition of the sediment.

In Japan,density and water content are regulated based on the Japan Industrial Standard “Test method fordensity of soil particles” (JIS A 1202) and “Test method for water content of soils” (JIS A 1203),
respectively.

1. Water content
The water content is the ratio of the mass of water lost during drying of homogeneous sediment to
the wet sediment. It is defined by the following equation:

w=

mpw
× 100
mwet

where

w : Water content (%)
mpw : Mass of water lost during drying (g)mwet : Mass of wet sediment (g)1-1 Measurement method

The measurement method is as follows:
1. Weigh the mass mc (g) of the container (heat-resistant) after heating and cooling. If the mass of thesample is below 10 g, use an electronic balance capable of reading the mass of 0.0001 g. If thesample mass is between 10~100 g, an electronic balance capable of reading the mass of 0.001 g isused. In addition, it is necessary to confirm that the mass of the container is constant (differenceof the minimum digit is within ± 5). Therefore, an average of two consecutive measurements isused as the mc value.
2. Place the wet sediment sample in a container and measure the gross mass ma (g).
3. Put the sediment sample in a constant-temperature drying oven together with the container and dry
it at 110 ± 5 °C to obtain a constant mass. It generally takes 12 to 24 hr to reach a constant massdepending on the amount of sample to be dried. When measuring pigments and organic matter inthe sediment, high-temperature heating should be avoided. In such cases, freeze each container,
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put the frozen sample together with the container in a vacuum freeze dryer, and dry the sample
after completing step 2.
4. Transfer the dried sample to a desiccator together with the container and measure the total mass mb(g) after cooling it to room temperature. If necessary, the drying and weighing processes arerepeated.

In case the sediment has high a content of organic matter or biogenic particles, the mass

may increase during measurement due to moisture absorption after drying.

Therefore, it isdesirable that the air temperature and relative humidity of the laboratory is controlled at 20~25 °C
and 50~60 %, respectively, during weighing. In addition, weighing should be done quickly after
taking out the sample from the desiccator.
1-2 Calculation

The water content is calculated as follows:w=

mwc − msc× 100
mwc − mc

wherew : water content (%)
mwc : Mass of container with wet sediment (g)msc : Mass of container with dried sediment (g)m c : Mass of container (g)2. Porosity
The porosity is defined as the ratio of the pore volume to the total volume of sediment sample.

In

general, it is denoted as φ:

φ=

Vpw
× 100
Vwet

where

φ:

Porosity (%)
Vwet : Volume of homogenous wet sediment (ml)Vpw : Volume of pore water in the wet sediment (ml)Because it is difficult to directly measure Vwet and Vpw, volume of wet sediment is calculated by
dividing the mass of dried sediment by dry bulk density. Otherwise, the porosity is calculated withthe following equation under the assumption that the volume of the wet sediment is the sum of thevolume of the solid phase and liquid phase (pore water) and the volume of pore water in the wet
sediment is equal to the volume of water reduced by drying. It should be noted that the mass of the
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dried sediment includes the mass of the salt precipitated by drying in addition to the mass of sedimentparticles. Therefore, the dry bulk density and the density of sediment particles used here are theapparent dry bulk density and the density of sediment particles including salts (see 2-8 and 2-4, 2-6).

φ=mpw ρ wt
mpw ρwt
× 100
100
=
×
ap
ms ρsap + mpw ρwt
ms ρ DB

where

φ : Porosity
mpw : Mass of water lost during drying (g)m s:Mass of dried sediment including salt (g)ρρρDensity of pure water under room temperature (kg m-3)

t
w:
ap
DB :
ap
s :

Apparent dry bulk density of the dried sediment with salt (kg m-3) (see section 2.6)
Apparent mean density of sediment with salt (kg m-3)

Additionally, by dividing the denominator and numerator by the mass of wet sediment mwet (g),the porosity φ (%) can also be expressed as a function of water content w (%), water density, andmean density of sediment (Berner, 1971).

φ=w 100ρ sap
× 100(1 − w 100)ρ wt + w 100ρ sap

2-1 Measurement method

The measurement method is as follows. Details follow the procedure described in Section 1-1.
1. Measure the mass of the container (beaker or plastic container) mc (g).
2. Place the wet sediment sample in a container and measure the total mass mwc (g).
3. Put the sediment sample in a constant-temperature drying oven together with the container or in a
vacuum freeze dryer after freezing.
4. Transfer the dried sample to a desiccator together with the container and measure the gross mass msc(g) after cooling it to room temperature.
5. Calculate the water content w according to Section 1-2.
2-2 Calculation

The porosity φ is calculated as follows:φ=w 100 ρsap
× 100
(1 − w 100)ρwt + w 100 ρsap
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In this calculation, use 998.2 kg m-3 (density of pure water at 20.0 °C) as the density of pure waterρw (kg m-3). In general, the mean density of sediment particles ρs (kg m-3) is about 2500 kg m-3(Berner, 1980).

However, the mean density of sediment particles can be changed due to thecomposition of sediment (content of organic matter, biogenic carbonate, and biogenic opal). In
addition, the apparent density of sediment particles ρsap (kg m-3) greatly varies with the amount ofsalt depending water content. Therefore, it is desirable to directly measure the mean density of andapparent density of sediment particles of each sample or each station. In the following sections,
methods for the density measurement of sediment particles are described.
2-3 Measurement method of density of sediment particles using a pycnometer

Measurement of density of sediment particles is as follows.

In the measurement, use an electronicbalance capable of reading the mass of 0.001 g.
1. Measure mass of a 50-ml pycnometer mf (g) after dried and cooled.
2. Remove the stopper of the pycnometer, fill with pure water so that bubbles do not stick on the innersurface, replace the stopper, wipe water drops on the outer surface of pycnometer, and measure thetotal mass m1a (g). The m1a is the sum of the mass of pure water m1w and the mass of apycnometer m c .
3. Remove the stopper, insert a thermometer in the pycnometer, and measure the water temperature
t1 (°C)
4. Discard water, dry the pycnometer. Pour about 15 g (about 1 cm height) of dried sediment into
the dried pycnometer, and measure the mass ms (g).
5. Add pure water up to about 2/3 of the pycnometer and leave it for more than 12 hours to remove air
bubbles in the sediment sample.
6. Heat the pycnometer containing the sample with a water bath for 1~2 hours. To remove bubbles,
gently shake the pycnometer sometimes during the heating. After air bubbles were sufficiently
removed, cool the pycnometer until the water temperature reaches room temperature.
7. Fill the pycnometer with pure water, set the stopper, wipe water drops on the outer surface of
pycnometer, and measure the total mass m a2 (g). The m a2 is the sum of the mass of pure water

mw2 , the mass of dried sediment ms, and the mass of a pycnometer mc .
8. Measure the temperature t 2 (°C) inside the pycnometer.
2-4 Calculation

By the method described in section 2-3, the mass of pure water m ws is calculated as follows:

mws = m1a + ms − ma2 = m1w − mw2The

mws corresponds to the volume of sediment particles in the pycnometer. To obtain the volume of thedried sediment, the buoyancy correction is applied to the mass of pure water, and divided by the density of pure
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water.

Because salt in the dried sediment dissolves to pure water by the step 7 in section 2-3, the obtained

volume is regarded as that of sediment particles without salt.

However, when the water temperature of purewater is different between steps 2 and 7, it is necessary to consider the volumetric change of the pycnometer due
to the density change of the glass.

[]Vc,1 calc = Vc1 1+ α v (t 2 − t1 )where

Vc1: Volume of pycnometer using at temperature t1 (ml).

Vc,1 calc : Volume of pycnometer using at temperature t 2 (ml).

The mass of a pycnometerm1a calc when it is filled with pure water at temperature t 2 (°C) is calculated

from the mass of the pycnometer m1a filled with pure water at temperature t1 (°C).
1a calcm(ρ − ρ )[1+ α (t − t )]=(m − m )+ m
ρ −ρ
2
w

air

v

1
w

2

1

1
a

c

c

air

where

m1a : Mass of the pycnometer filled with pure water at temperature t1 (°C) (g)ma2w : Mass of the pycnometer at when it is filled with pure water at temperature t 2(°C) (g)1t 2 : Temperature inside of the pycnometer at when ma was measured (°C)
t : Temperature inside of the pycnometer at when ma2 was measured (°C)
m c : Mass of the pycnometer (g)ρ1w : Density of pure water at temperature t1 (°C) (kg m-3)
ρw2 : Density of pure water at temperature t 2 (°C) (kg m-3)

ρair : Density of air (kg m-3)
α v : Coefficient of cubical expansion of the pycnometer (K-1)

The density of air is lower than that of pure water, and the coefficient of cubical expansion of glassis negligible if the difference between t1 and t 2 is within 2 °C. Since the relative influence of theseterms on m1a calc is less than 0.05%, the above equation can be simplified as the follows:1
a calcmρw2 1= 1 (ma − mc )+ mc
ρw
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Considering the change in temperature during the measurements, the mass of pure water mws is
calculated as follows:

mws = m1a calc + ms − ma2 = m1w calc − mw2

where

m1w calc : Mass of pure water considering the temperature change of the mass of pure water fromm1w (g)(ρ − ρ )[1+ α (t − t )]
2
w

air

1
a calc=1
w calcρw2 1= 1 mw
ρw

m

v

2

1

ρ − ρair
1
w

m1w

or,

m

Thus, the volume of sediment particles measured by a pycnometer Vsolid (ml) becomes as follows:

Vsolid =

where

(m

1
w calc− mw2

1 − ρ air ρweight) 1− ρ

ρw2 × 10 −3

air

ρw2

ρweight : Density of a balance weight (kg m-3)

The mean density of the sediment particles is calculated by dividing the volume of sedimentparticles Vsolid by mass of dried sediment ms. Since the mass of dried sediment ms includes the mass ofsalt originated from pore water, the apparent density of sediment particles

ρsap is calculated with thefollowing equation:

ρsap =

ms

1 − ρ air ρweight1 − ρair ρ sap
× 10 3
Vsolidmρsap =  1 s 2 (ρ w2 − ρair )+ ρair  × 10 3
 mw calc − mw
If the above-mentioned processes are performed using the desalted dried sediments, the mean
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density of sediment particles ρs can be obtained. For the desalting of the dried sediment, a properamount of dried sediment is put in a 50 ml centrifuge tube, add 50 ml of pure water, centrifuge, andremove the overlying water.

These processes are repeated for four times. When the dry mass of thedesalted sediment is defined as mssalt free , the density of sediment particles ρs can be calculated by thefollowing equation.

ρs =mssalt free

1 − ρair ρweight1 − ρair ρs× 10 3
Vsolid m salt free32
ρs =  1 s
ρ
−
ρ
+
ρ
air  × 10
air )
2 ( w
 mw calc − mw


2-5 Measurement method of density of sediment particles using a gas pycnometerIn recent years, density measurement using a helium (He) gas pycnometer has been widely usedinstead of the wet density measurement described in section 2-3.

Fig. 1 shows the principle of themeasurement by a gas pycnometer. The volume of the sample used for the analysis is expressed by
the following equation

Vs' = Vcell −Vexp
p1 − pa−1p2 − pa

Using the atmospheric pressure as a reference, the above equation becomes as follows.

Vs' = Vcell −

Vexp
p1
−1
p2

where,

Vs' : Total volume of dried sediment Vs and sample container Vc (ml)Vcell : Volume of sample cell (ml)Vexp : Volume of expansion cell (ml)pa : Pressure when all cells are replaced with He gas and at the ambient pressure (kPa)
p1 : Pressure when sample cell is replaced and pressurized with He gas (kPa)p2 : Pressure in the entire system when the valve between the both cells is open (kPa)
When measuring the volume of dry sediment with a gas pycnometer, the dry sediment is placed in a
glass or plastic container, etc.

For this reason, it is necessary to measure the volume of the container

first and subtract the volume from the total volume of dry sediment and containers with the following
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equation.

Vs = Vs' − Vc
where,

Vs : Volume of dry sediment (ml)Vc : Volume of sample container used for the measurement (ml)The volume of dry sediment measured by a pycnometer, Vs , includes volume of salt separated
from seawater during the drying process. In order to estimate actual volume of dry sediment, it isnecessary to subtract the volume of salt from Vs .

Fig 1: Schematics of operating sequence of agas pycnometer2-6 Calculation

The mass of the wet sediment is the sum of the masses of the sediment particles, the water lost by
drying and the precipitated salt as shown below.
mwet = msolid + mw + msalt
wheremwet : Mass of wet sediment (g)msolid : Mass of sediment particles (g)mw : Mass of water lost during drying (g)m salt : mass of salt evaporated during drying (g)Guideline of ocean observations Vol. 5 Chap. 2
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The mass of dry sediment ms, described in section 2-4, is the sum of masses of the sedimentparticles and salt.

ms = msolid + msalt

Considering that the mass of water lost during the drying m w is derived from pore water, the massof the precipitated salt m salt can be estimated using the absolute salinity S . Furthermore, bydividing m salt by the density of the salt ( ρsalt : 2200 kg/m3), the volume of the salt Vsalt can becalculated.

The volume of the sediment particles Vsolid can be determined by subtracting thevolume of salt Vsalt from the total volume of the dry sediment VS .
In this calculation, it is preferable to use the practical salinity of seawater in the bottom layer at the
sampling point as the absolute salinity of pore water.

Sm
10 − S w
msalt
Vsalt =
ρsalt × 10 −3
msalt =

3

Vsolid = Vs − Vsalt
wherem salt : Mass of salt evaporated during drying (g)mw : Mass of water lost during the drying (g)S : Absolute salinity (g/kg)
Vsalt : Volume of salt (ml)ρsalt : Density of salt (2200) (kg m-3)
Vsd : Volume of dry sediment (ml)Vsolid : Volume of sediment particles (ml)In addition, the density of sediment particles can be calculated by dividing the value obtained bysubtracting the mass of salt m salt from the mass of dried sediment with salt ms by the volume of
sediment particles.

ρs =ms − msalt
× 10 3
Vsolid

2-7 Estimation of porosity from given volume of a container

For the estimation of the porosity as described above, it is necessary to assume or measure theapparent density of the sediment particles in addition to the density of the pure water. The apparent
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density values largely affect the porosity.

Because the apparent density is necessary to determine thevolume of the wet sediment samples, the porosity can be measured without using the apparent densityof the sediment particles by filling the wetting sediment into a container with a given volume. The
methods are as follows. The detailed procedures are described in Section 2-2.
1. Weigh the mass of a given volume of heat-resistant plastic container, mc (g), after heating andcooling.

If the sample is less than 10 g, use an electronic balance capable of reading a mass of

0.0001 g. The volume of container, Vc (ml), is measured in advance.
2. Fill the wet sediment sample into the container and weigh the gross mass mwc (g).

Care should

be taken not let bubbles into the container.
3. Put the sediment sample in a constant-temperature drying oven together with the container or in a
vacuum freeze dryer after freezing.
4. Transfer the dried sample to a desiccator together with the container and measure the gross mass
msc (g) after cooling it to room temperature.

2-8 Calculation

The porosity φ can be calculated using the following equation. This method can be applied to
calculate the water content w (%) according to Section 1-2.

φ=(mwc − msc ) ρwt × 100
Vc

where

ρ wt : Density of pure water at temperature t (°C) (kg m-3)
mwc : Gross mass of container including wet sediment sample (g)msc : Gross mass of container including dried sediment sample (g)Vc :Volume of the container (ml)Additionally, by using a container with a given volume, the apparent dry bulk density of sediment

ρ

ap
-3
DB (kg m ) can be estimated as follows:

msc − mc
× 1000Vcm= s × 1000
Vc

ap
=
ρDB

where
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ap
ρDB: Apparent dry bulk density (kg m-3)

msc : Gross mass of container including dried sediment sample (g)m c : Mass of container (g)ms: Mass of dried sediment containing salt (g)Vc : Volume of the container (ml)The apparent dry bulk density of sediment ρDB can be calculated by dividing the value obtainedby subtracting the mass of salt m salt from the mass of dried sediment containing salt m s by thevolume of sediment particles Vc .

ρDB =ms − msalt
× 1000Vc

2-9 Effect of salinity on measurement of physical properties of sediment

In the previous sections, except for the measurement using a gas pycnometer, pore water is regarded
as pure water in calculations of water content, porosity, mean density of sediment particles and dry
bulk density. However, the pore of the sediment collected by the sampling is usually filled withseawater. By evaporating the pore water during drying, the salt in the pore water is precipitated.
Consequently, and the mass of dried sample includes the masses of sediment particles and theprecipitated salt. Therefore, when considering the pore water as seawater, it is necessary to assume
absolute salinity S (g kg-1) of seawater for calculations.

The water content, porosity, mean density ofthe sediment particles, and the dry bulk density are shown in the following equations for cases where
the absolute salinity of pore water is S (g kg-1) and the pore water is regarded as pure water.
In the case of saline water
Water content

w=

10

3

(10 − S) m × 100

φ=

w=

w

mwet

mw
× 100
mwet

[m 10 (10 − S)] ρ
m ρ
× 100
× 100 φ =+m ρmρ(m − m ) ρ + [m 10 (10 − S)] ρ
3PorosityIn the case of pure water

3

3

t
sw

w

3

s

salt

s

w

3

t
sw

s

w
ap
s

t
w

w

t
w

When pore water is regarded as pure water, the water content is underestimated by about 3.45%
compared with the case saline pore water with salinity of 34.5g kg-1. With regard to the porosity,
even when regarding it as pure water, there is practically no problem if the apparent density ofparticles of sediment containing salt is used as density of sediment. However, it should be noted thatthe water content will be underestimated by 0.2~0.02% where the water content ranges 50 and 90%
and by about 0.7% where the water content is 10%.
Salinity corrected

Salinity uncorrected

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Density of sediment particles
mssalt free3212 (ρ w − ρ air )+ ρ air × 10
 mw calc − mw

ρs = 

Dry bulk density

ρDB =



ρsap =  m

ms − msalt(ms − msalt ) ρs + [mw10 (10 − S)] ρ
3

3

t
sw


ms
3
2

2 (ρ w − ρ air )+ ρ air × 10
− mw


1
w calc× 10 3 ρDB =ms
× 10 3ms ρsap + mw ρwt

or,
ρDB =

ms − msalt
× 10 3
Vc

ρDB =

ms
× 10 3
Vc

Both the density of sediment particles and the dry bulk density are influenced significantly
depending on the presence and its extent of absolute salinity.

For example, a sediment sample with awater content of 95%, assuming the absolute salinity of 34.5 g kg-1, the salt contributes 3.39 g on 1.61
g of the weight of sediment particles.

In general, salinity of pore water is estimated by measuring thechlorine content and multiplying by 1.86055.

However, the absolute salinity of pore water varies

vertically due to dissolution of carbonate and biogenic opal, loss of magnesium or potassium due toreverse weathering, does not necessarily have a positive relationship with the chlorine content.
Determination of the absolute salinity of pore water is practically difficult. When estimating watercontent, porosity, mean density of sediment particles and dry bulk density, it is advisable to substitutethe practical salinity of seawater in the bottom layer at the sampling point. Changes in water content
and porosity due to 1 g kg-1 difference in absolute salinity are less than 0.1%, and the change in meandensity of sediment particles is about ~0.3%. When the water content is 90% or more, the dry bulk
density varies by up to 7% due to the change in absolute salinity of 1 g/kg, but the variation is lessthan 1% except this case.
In addition to importance as physical property value the dry bulk density is crucial for estimating
inventory I (mol m-2 or g m-2) and flux of a target component F (mol m-2 yr-1 or g m-2 yr-1) by thefollowing equations.

I = ∫ 0 C ρ DB × 10 −3 dzz

F = C ρDB × 10 −3 Sr
where
z:

Depth in sediment (m)C : Concentration of a target component in sediment (mol g-1 or g g-1)
ρDB : Dry bulk density (kg m-3)
Sr : Sedimentation rate (m yr-1)
In general, the concentration of a chemical component of the sediment is measured as the amount or
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mass of the component per dry weight of dry sediment containing salt, in order to avoid changes
during the desalination process such as desorption of the target component. Therefore, there is no
problem to use the pure water-based dry bulk density in calculating the abundance or flux of the target
component.

Conversely, when calculating the inventory or the flux using the saline water-based dry

bulk density, the concentration of the target component in the sediment must be conversed asconcentration per mass of salt free dry sediment, and multiply the saline water-based dry bulk density.

(10 − w)(1 − S 10 )C2

Csalt free =3

10 2 − S 10 − w

where

Csalt free : Concentration of a component without containing salt (mol g-1 or g g-1)
S : Absolute salinity (g kg-1)
w : Water content (%), equivalent to mass of pure water per 100 g of wet sediment (g)References
Meade, R.H. (1966): Factors influencing the early stages of the compaction of clays and sands – review. J. Sed.
Petrology, 36, 1085-1101.
Nafe, J.E. and C.L. Drake (1957): Variation with depth in shallow and deep water marine sediments of porosity,
density and the velocities of compressional and shear waves. Geophysics, 22(3), 523-552.
JIS A 1202, Test method for density of soil particles, Japanese Standard Association, Tokyo, (2009).
JIS A 1203, Test method for water content of soils, Japanese Standard Association, Tokyo, (2009).
Berner, R.A. (1971): Principles of Chemical Sedimentology. McGraw-Hill, New York, 92 pp.
Berner, R.A. (1971): Early Diagenesis A Theoretical Approach. Princeton Series in Geochemistry. Princeton
University Press, Princeton, NJ, 241pp.

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Loss on ignition○Hisashi NARITA (Tokai University) /Shigeyoshi OTOSAKA (Japan Atomic Energy Agency)

As a method to estimate the organic carbon content in sediments, the loss of weight after
combustion at 550 °C (loss on ignition: LOI) is commonly used (e.g., Dean, 1974, Heiri et al., 2001).
In the LOI method for suspended and sinking particles in seawater, samples are combusted at 450 °C(e.g., Honjo, 1980; Tsunogai et al., 1982) to estimate the organic carbon content. On the other, theJapan Industrial Standard (2009) recommends combustion at 750 ± 50 °C until the mass of the sample
is constant. The conditions used in the LOI method may greatly vary. For example, the incineration
temperature ranges from 200~1600 °C, the time varies from 1~16 hours, and the amount of the sample
is unreported in most cases (Luczak et al., 1997).

Luczak et al., (1997) also pointed out theimportance of the combustion temperature, time and sample size and recommended optimum
conditions (500 °C and 5 hr for 2 g of sample size).
Results from the LOI method may be affected by the loss of mass due to dehydration andhydrolysis of clay minerals, requiring varying analytical technique, also based on the clay content of
sediments (Dean, 1974). The temperature of dehydration and hydrolysis of clay minerals greatlychanges depending on the type of clay mineral (Grim and Bradley, 1947).
biogenic minerals such as calcium carbonate and opal.

Seabed sediments contain

It is generally known that calcite isdecomposed at 800~850 °C and dolomite, CaMg(CO3)2, is thermally decomposed at 700~750 °C andrelease CO2.

Kamatani (2000) pointed out that calcium carbonate is not decomposed at atemperature of ~500 °C, but dolomite is partly decomposed and releases CO2. In addition, Hirota and
Szyper (1976) reported that the thermal decomposition of calcium carbonate occurs at temperatures
above 550 °C and recommend combustion with careful temperature control (500 °C or slightly lower)using an electric muffle furnace.

Biogenic opal in sediment contains on average 10% water(Mortlock and Froelich, 1989).

This water dehydrates during diagenesis processes and opal

undergoes a phase transition first from opal A to opal CT, and then to quartz (Mizutani, 1970). The
water in the opal is also lost by heating; the loss is 60-70 % at 200 °C. Approximately 100 % ofwater in opal dehydrates during heating to 1000 °C (Knauth and Epstein, 1982). These facts indicatethat high-temperature incineration at 550 °C or higher should be avoided when performing LOI. The
LOI method can also be affected by insufficient temperature control of the electric muffle furnace andunevenness of the temperature in the furnace.
As mentioned above, the LOI method has been widely used as an indicator of the organic
matter content; however, the loss of weight is not only due to the combustion of organic matter but
also the dehydration and hydrolysis of clay minerals or dehydration of calcium carbonate and opal.
Considering the effects of dehydration and hydrolysis, combustion at a temperature below 550 °C is
reasonable when measuring the LOI of marine sediments.

With regard to detailed temperature

conditions for heating, analysts should make decisions based on the sampling locations andcomposition of major components. Preliminary experiments are strongly recommended to determine
optimal heating condition.
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G503EN-2

1. Measurement method
The measurement method is as follows. The details follow the procedure described in Section 2-2.
1. Measure the mass of a crucible or a glass container (heat-resistant), mc (g), after heating and cooling.
Use a balance with a minimum scale of 0.001 g or less. The mass is measured twice and theaverage value is used as mc (g).
2. Place 2 g of dried sediment sample in the container, heat it at 110 °C for 2 hr, and measure the total
mass ma (g).

If extra material, such as wood fragments, is present in the sample, it should be

removed beforehand. Additionally, it is advisable to pass the sample through a 2 mm sieve.
3. Place the sediment sample in a muffle furnace together with the container and gradually raise thetemperature to 550 °C.

When it reaches to the target temperature, maintain the temperature, andheat it for 5 hr.
4. After heating, open the door of the muffle furnace for ~10 min, remove the sample containers with acrucible tongs, and expose them to room temperature for a couple of minutes. Transfer thecontainers to a desiccator and measure the total mass mb (g) after cooling them to room
temperature.
2. Calculation
The LOI (%) is calculated as follows.

LOI =ma − mb
× 100
ma − mc

where,

LOI : Loss of ignition (%)
ma : Mass of container with dried sediment (g)mb : Mass of container with combusted sediment (g)mc : Mass of container (g)References
Dean, W.E. (1974): Determination of carbonate and organic matter in calcareous sediments and sedimentaryrocks by loss on ignition: comparison with other methods. J. Sed. Petrol. 44, 242–248.
Heiri O., A.F. Lotter and G. Lemcke (2001): Loss on ignition as a method for estimating organic and carbonate
content in sediments: reproducibility and comparability of results. J. Paleolim. 25, 101–110.
Honjo, S. (1980): Material fluxes and modes of sedimentation in the mesopelagic and bathypelagic zones. J. Mar.
Res., 38, 53-97.
Tsunogai, S., M. Uematsu, S. Noriki, N. Tanaka and M. Yamada (1982): Sediment trap experiment in thenorthern North Pacirfic: Undulation of settling particles. Geochem. J., 16, 129-147.
JIS A1226, Test Method for Ignition Loss of Soils, Japanese Standard Association, Tokyo, (2009).
Luczak, C., M.-A. Janquin and A. Kupka (1997): Simple standard procedure for the routine determination oforganic matter in marine sediment. Hydrobiologia, 345, 87–94.
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G503EN-3

Grim, R.E. and W.F. Bradley (1948): Rehydration and dehydration of the clay minerals. American Mineralogist,
33, 50-59: Illinois Geological Survey Report Inv. 134.
Pansu, M. and J. Gautheyrous (2006): Handbook of soil analysis: Mineralogical, Organic and Inorganic
Methods. Springer, pp 10.
Kamatani, A. (2000): Measuring Biogenic Silica of Marine Samples : its Situation and Prospect.

Umi noKenkyu (Oceanography in Japan), 9 (3), 143-159.
Mortlock, R.A. and P.N. Froelich (1989): A simple method for the rapid determination of biogenic opal inpelagic marine sediments. Deep-Sea Res., 36 (9), 1415-1436.
Mizutani, S. (1970): Silica mineral in the early stage of diagenesis. Sedimentology, 15, 419-436.
Knauth, L.P. and S. Epstein (1982): The nature of water in Hydrous silica. American Mineralogist, 67, 510-520.

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Grain size distribution○Hisashi NARITA (Tokai University) /Shigeyoshi OTOSAKA (Japan Atomic Energy Agency)

The grain size is fundamental parameters reflecting the basic physical properties of marine
sediment. The grain size distribution of the marine sediment is mainly influenced by the compositionof terrestrial detritus, biogenic calcium carbonate and opal.

Stokes' law indicates that the sinking

velocity of a particle in seawater is proportional to the square of its diameter. The grain size of theterrestrial detritus therefore reflects transport and deposition processes, as well as provenance anddispositional environment. It is also known that there is a certain relationship between the size
distribution of the terrestrial detritus and its chemical composition (Kitano, 1972; Terashima et lal..,2008).
In general, detrital particles in sediment can be classified into stone, gravel, sand, silt, and clay
depending on the particle size.

However, the boundary value of each size class is not standardized,

neither internationally nor academically.

In Japan, based on the Japanese Industrial Standard “Testmethod for particle size distribution of soils” (JIS A 1204), boundaries of particle size classes ofground material are definedin “Method of classificationofgeomaterials

forengineering purposes” (JGS0051) of the GeotechnicalSociety standards (Fig.1).
The typical sizes of biogenic
opal and carbonate in marine
sediments are indicated inFig. 1. The Wentworth sizeclassification (Fig. 1), whereparticle size is divided into
1/2n mm sections and thephi-scale (φ) represents
grain size, is often used bygeologists(Wentworth,Fig. 1 Typical diameter of various particles in marine sediments

1922).

φ = −log2 (d d0 )where
: Particle diameter (mm)d0 : 1 mm (unit value for creating a dimensionless parameter)
However, particles in marine sediment are typically not spherical but exhibit various,
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irregular shape. Additionally, the particle density is not uniform. When discussing the particle size insediments under such circumstances, it is necessary to define the particle size. The particle size isdefined according to the measurement method. For the measurement of the grain size of the marine
sediment, the 1) sieving method, 2) settling method, 3) Coulter counter method, and 4) laser
diffraction-scattering method are mainly used.
1. Methods for grain size analysis
1) Sieving method
Sieving is a simple and direct method and is used for grain size measurement of sandy and gravel
sediments. Sieves with mesh apertures of 75 µm, 106 µm, 250 µm, 425 µm, 850 µm, 2 mm, 4.75mm, 9.5 mm, 19 mm, 26.5 mm, 37.5 mm, and 53 mm are used for the sieving analysis (JIS A 1204).
Sieve the well-dried sediment sample, shake it with a shaker, and measure the mass of the sample
above each sieve.

The particles size remaining on the sieve is conceptually proportional to theintermediate axis of the particle.
2) Settling method
In the settling method, sediment particles are suspended and settled in a sedimentation cylinder
containing a dispersant such as sodium hexametaphosphate solution. This method is divided into
four categories: a) hydrometer method, b) pipette method, c) settling mass method, and d) lighttransmittance method. The detection method of the temporal change in sedimentation of particles ofthese methods differs depending on the particle size, density, and density difference between thedispersant and particles.
In method a, the density of the suspension solution is measured with a hydrometer atsystematic time intervals. In method b, a given amount of a suspended solution in a cylinder ofknown-height is withdrawn from a particular depth at appropriate time intervals. In method c, aweighing dish is placed at a certain depth in a sedimentation cylinder and the temporal change in themass of particles deposited on the weighing dish is measured. In method d, the temporal change inthe transmittance caused by the sedimentation of particles is measured by applying light from the sideof the sedimentation cylinder.

Based on these methods, the particle diameter (Stokes’ diameter) canbe obtained assuming spherical particles. This particle size is called effective diameter. Using
methods a and b, particles with diameters of 1~50 μm can be measured; particles with diameters of
0.2~200 μm and 0.2~100 μm can be measured with methods c and d, respectively (Okubo, 1989).
3) Coulter counter method
The Coulter Counter is an electrical sensing zone method, which determines the number and sizeof particles suspended in an electrolyte by measuring the electric resistance.

A glass tube with poresfilled with an electrolyte solution is inserted into a glass vessel filled with the same electrolyte solution
and the electric resistance between two electrodes arranged on both sides of the glass tube is measured.
Because the inside of the inner glass tube is adjusted to a negative pressure, the particles and solution
move through the pores inside the glass tube when the particles are uniformly suspended in the
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solution in the outer glass vessel.

At this time, the electric resistance of the electrolyte solutionchanges according to the volume of the particle. The change in resistance is detected as an electricalpulse and the number of particles and volume of each particle can be measured. Because thediameters of the individual particles are calculated from the volume, the particle diameter obtained isan equivalent diameter.

It is possible to measure the number and volume of the particles with aparticle size ranging from 0.4~1200 μm.
4) Laser diffraction scattering method
The laser diffraction-scattering method is a measurement method using light properties. When alaser enters the suspension solution, light is diffracted or scattered in various directions by the particles.
The distributional pattern of the intensity of diffracted and scattered light depends on the particle size.
When the particle diameter is larger than the wavelength of the laser light, the Fraunhofer diffraction isdominant and the light converges toward its traveling direction. On the other hand, Mie scattering
becomes dominant when the particle diameter is equal to or less than the wavelength of the laser light.
Assuming spherical particles, the scattering intensity increases in the traveling direction if the particles
are ~1 μm in diameter; the scattering intensity increases laterally and backward if the particles are ~0.1
μm in diameter.
Because the object to be measured is not a single particle but a group of particles with various
shapes, a distributional pattern of intensity of the actual diffracted and scattered light is asuperimposition of diffracted and scattered light from individual particles. Therefore, the particle size
distribution can be obtained by detecting and analyzing the distributional pattern of the light intensity.
However, in the laser diffraction-scattering method, the particle size dependency of the scatteredpattern is lost when the particle diameter is less than half of the wavelength of the laser light.

In

addition, when the particle diameter reaches approximately 1/10 of the wavelength, Rayleighscattering becomes dominant and the scattering intensity decreases in inverse proportion to the fourth
power of the wavelength. Therefore, when measuring a sample including particles with various sizes
and shapes, the sensitivity is significantly lowered by the influence of the scattered light of particles
with a large particle diameter. Nevertheless, recent improvement of the optical system enabled themeasurement of a wide range of particle sizes. It now is possible to measure particles with a particle
diameter ranging from 0.02 to 2000 μm.

Because the particle diameter is considered to be spherical,

an effective diameter is obtained by this method.
The upper limits of the measurable particle size are 50 to 200 μm for of the settling method,
1200 μm for the Coulter counter method, and 2000 μm for the laser diffraction-scattering method.
When measuring the particle size distribution of the seabed sediments, it is necessary to use thesemethods in combination with the sieving method. The sieving and settling method (except for thelight transmission method) measure the mass-based distribution of particle size, whereas the lighttransmission method, Coulter counter method, and laser diffraction-scattering method generally
measure the number- or volume-based distribution.

Therefore, the volume-based particle size

distribution needs to be converted to mass-based distribution using the particle density. Because theseabed sediment consists of particles with various densities, the average density is used for the
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conversion.

However, except for the sieving and pipette methods, determine the average density ofeach particle size fraction is fundamentally complicated and subject to uncertainty, and an estimateddensity value is generally used.
2. Measurement of particle size distribution by sieving and settling methods
Marine sediments consist of various particles, such as detrital particles, biogenic carbonate andopal, and organic matter. If the seabed sediments contain biogenic carbonate, biogenic opal, andorganic matter (organisms), these particles may cause bias in the measurement of the particle size
distribution. The autogenous mineral coated on the surface of the detritus or salts in the pore water
can also bias the results. A combined sieving and settling methods of detrital particles is described in
the following section in addition to procedures to exclude the factors that bias the particle size
distribution. The dissolution procedure of biogenic carbonate and opal can be omitted, to measure
the particle size distribution of bulk sediment. However, application of this method to calcareous andsiliceous mud with a high content of carbonate and opal in hemipelagic and pelagic region isextremely difficult because of its difficulties to collect enoguh volume of sample. It should beconsidered that this method is applied to sediments that mainly consist of lithogenic material withrelatively low content of carbonate and opal such as coastal sediment. To measure the grain size
distribution of sediments with high content of carbonate and opal, it is recommended to apply the laser
diffraction/scattering method described in Section 3 that permit measurement with a small volume ofsamples.
2-1 Sample dividing and preparation

Approximately 20 g (wet weight) of the collected sample is taken and used for measurements of watercontent, ignition loss and various chemical analyses and the remainder is used for particle size analysis.
Although the quadrisection method (also known as a “cone and quarter”) is recommended for thedivision of the sample, there is generally no issue, even if an appropriate amount is sorted for sediment
samples consisting of fine particles.

From the viewpoint of accuracy, the mass of the sediment

sample for particle size analysis is provided in JIS A 1204 as a function of the maximum particle size.
The minimum sample mass is ~200 g for the sample with the maximum particle size of 2 mm and~400 g for the sample with the maximum particle size of 4.75 mm (Table 1).

In the settling method,~115 g (dry mass) of sandy sediment (< 2 mm fraction) is required and ~ 65 g is required for silty or
clay sediments.
In JIS A 1204, it is recommended to first divide the sediment sample into two fractions of graveland sand to clay using a 2 mm sieve.
usedbecausedifficulttoitHowever, in the case of marine sediments, dry samples areisdirectly

divide the wet sample
into two fractions with
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a 2 mm sieve.

In such a case, fine particles are agglomerated by heating and drying and it isnecessary to physically disperse them before sieving.

Also, it is desirable to perform freeze-drying

because there is a possibility of breakage of coarse particles during physical dispersion.

The

sediment sample is relatively easy to disperse after freeze-drying. The mass of the sediment sample
is measured before and after drying with an electronic balance capable of reading a mass of 1 mg and0

the water content w (%) is calculated. The mass of samples after drying is m s (g).
The dried sample is sieved and divided into two fractions; the fractions are passed through a 2
mm sieve and the residue remains on the 2 mm sieve. When sieving, fine particles adsorbed on thesurface of coarse particles on the sieve are removed as much as possible. For this process, it is
helpful to use an electromagnetic sieve shaker. However, excessive shaking may cause breakage ofparticles. When there are many contaminants, such as wood and shell fragments and organisms, thesieving efficiency may be reduced.

In such a case, it is desirable to remove them by hand after

confirming that the mass of fine particles on their surfaces can be ignored. The mass of the sediment0

passed through a 2 mm sieve is denoted as m1s (g) and the mass of the residue on the 2 mm sieve is

m0s0 (g) .
Based on the above-mentioned procedures, evaporated salt is precipitated on the surface of fineparticles.

Additionally, the sample may contain a considerable amount of biogenic opal, calcium

carbonate, and organic matter.

Because such biogenic particles interfere with the particle size

measurement during sieving and settling, it is necessary to remove them chemically or physically.
The detailed procedures are listed below.
1. For passing sediment samples through a 2 mm sieve, accurately weigh in ~100 g (in dry weight) for
sandy sediments and ~60 g for silt and muddy sediments, place the samples in a 1000 ml tall beaker,
1

and record the mass m1s (g).

The residue on the 2 mm sieve is washed with pure water toremove fine particles from the surface of coarse particles. Transfer the residue to a beaker, dry it
1

in a constant-temperature oven at 110 °C, and measure the mass m 0s (g) after drying. Add 200
ml of pure water to the sample in a beaker such that all samples are immersed in pure water.
2. Add 50 ml of hydrogen peroxide solution, stir thoroughly, leave the solution for 12 hr or more, andheat at 80 °C for about 3 hr on a hotplate to decompose the organic matter. If the sample has ahigh content of organic matter, bubbles are generated vigorously. Samples containing a large
amount of manganese oxide explosively react with hydrogen peroxide and may be blown out
together with the solution. In such a case, it is necessary to moderate the reaction by adding purewater as necessary.
3. Add 250 ml of 1 M hydrochloric acid or acetic acid-sodium acetate buffer solution adjusted to pH 5,
stir thoroughly, and leave for at least 12 hr to dissolve biogenic calcium carbonate.
4. Add 500 ml of pure water, stir thoroughly, and let it stand for 24 hr or more. For the sample of 2
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mm sieve residue, it is enough to let it stand for several minutes. After the sediment particles
settle, remove the solution by decantation or centrifugation.
5. Transfer the sample to a 500 ml polyethylene beaker. Add 300 ml of 0.1 mol L-1 sodium carbonate,
cover the beaker with a Teflon watch glass, and incubate it in a constant- temperature oven at 85 °C for 1 hr.
6. After allowing the sample to cool, add 120 ml of 0.5 mol L-1 hydrochloric acid solution and stir wellto neutralize, let stand for 24 hr or more, and then remove the solution by decantation or
centrifugation.
7. Transfer the sediment sample to a centrifuge tube with 80% ethanol and remove the solution by
centrifugation.

This process also facilitates to remove eluted cations (Jackson, 1956).

To

remove ethanol, add pure water. The solution is removed by decantation or centrifugation.
The above-mentioned steps 3-6 can be omitted if unnecessary.

Especially for samples

fractions >2 mm, steps 5 and 6 are not required. Step 5 aims to removal biological opal, but it is
known that a considerable proportion of clay minerals also dissolves by this procedure (DeMaster,1981). Additionally, it is necessary to recognize that the particle size distribution of the sample may
be changed to a certain extent.
2-2 Sieving analysis of sediment particles remaining on 2 mm sieve
2-2-1 Sample

The samples for sieving analysis are processed by the following procedure:
1. Wash the residual reagent thoroughly with water.
2

2. Put the sample in a constant-temperature oven at 110 °C and measure its mass m0s (g).
2-2-2 Sieving

The sieving of the sample is performed according to the following procedure:
1. Sieve the dried sediment samples using 75 mm, 53 mm, 37.5 mm, 26.5 mm, 19 mm, 9.5 mm and4.75 mm sieves.
2. Sieve using an electromagnetic sieve shaker for 10 min.
3. Measure the accurate mass m (di ) (g) of the sample remaining on each sieve with the electronicbalance. During this process, carefully confirm that the particles remaining in the sieve do notcontain any plant and shell fragments. If such contaminants are found on the sieves, remove themby hand using tweezers.
2-3 Settling analysis of sediment particles passed through a 2 mm sieve and sieving analysis of sedimentparticles after the settling analysis
2-3-1 Sample

Samples to be subjected to settling analysis are prepared by the following procedure:
1. After samples are passed through a 2 mm sieve, they are dried in a vacuum freeze dryer and the total
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2

mass m1s (g) is determined with an electronic balance. Approximately 15 g of the dried sample
3

is separated for density measurement and the mass of the remaining sample m1s (g) is measured
with an electronic balance.
2. Add 200 ml of pure water, stir thoroughly such that the whole sample is immersed in pure water,
and leave it in a thermostatic chamber for 15 hr or more.
3. After standing, add pure water to reach the total volume of ~700 ml. Add 10 ml of 20 % sodium
hexametaphosphate solution by stirring and disperse the sediment particles using a dispersing
device or ultrasonic bath.
2-3-2 Settling analysis

The sedimentation analysis of samples is performed according to the following procedure:
1. Transfer the dispersed sample to a sedimentation cylinder and adjust the total volume to 1000 ml
using pure water.
2. Place the sedimentation cylinder in a thermostatic chamber and leave it until the temperature of thesuspension solution is equal to the room temperature. Keep stirring the solution with a magnetic
stirrer during this process.
3. Securely cover the open end of the cylinder with a silicon stopper and secure it with the palm of
your hand.

Subsequently, turn the cylinder upside down and back upright for a few minutes.

At

this point, it is necessary to avoid the suspension leaking out from the cylinder and to ensure thatthe sediment is completely mixed in the suspension. Set the cylinder in a thermostatic chamberand record the time.
4. After 1, 2, 5, 15, 30, 60, 240 and 1440 minutes, carefully lower the hydrometer into the cylinder and
let it float in the sediment suspension.

Record the density and temperature of the suspension.

The density read until 0.0005 (half of a minimum scale) at the upper level of the meniscus after
stopping the hydrometer bobbing motion. The hydrometer is left in the cylinder for 1 to 2 min.
In the other case, the hydrometer is carefully removed from the cylinder after reading. Rinse thehydrometer and thermometer with pure water and completely dry them.
2-3-3 Sieving analysis after the settling analysis

The above-mentioned procedures cannot be used to measure the particle size distributions from 250µm to 2 mm.

Therefore, to measure size distributions of this size interval, it is necessary to sieve

sediment using settling analysis.
1. After settling analysis, the sedimentation cylinder is vigorously rotated hand-over-hand for a few
minutes to generate the suspension solution. All of the suspension solution is passed through a 75
µm sieve. The sediment samples on the sieve are carefully washed with running water to remove
fine particles less than 75 µm. Put the sample in a constant-temperature oven at 110 °C and4

measure its mass m1s (g).
2. Sieve the dried sediment samples using 850 µm, 425 µm, 250 µm, 106 µm, and 75 µm sieves.
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3. Sieve using an electromagnetic sieve shaker for 10 min.
Measure the accurate mass m1 (di ) (g) of the sample remaining on each sieve with the electronicbalance.
2-3-4 Hydrometer and its calibration

Use a hydrometer for soil with a scale range of 0.995 to 1.050 g cm-3 and a minimum scale of 0.001 g
cm-3.

Because the reference temperature is generally 15 °C when using the hydrometer, it isnecessary to obtain the density at that temperature and correct the density with the following equation.

∆ ρ = ρ αV (15 − t )where∆ ρ : Difference of density to be corrected (g cm-3)

ρ ：Reading of density on hydrometer (g cm-3)
αV ：Volume expansion coefficient (K-1) of hydrometer glass. A hydrometer should
be made of transparent glass that has a volume expansion coefficient of 25 ± 5
x 10-6 (K-1; JIS B 7525). The expansion coefficient is calculated as the third
power of linear expansion coefficient.

t : Temperature at the time of measurement (°C)
The scale of a hydrometer must be readwith the specified eye level of reading (readthe scale at the top or bottom of meniscus,
depending on the hydrometer; Fig. 2).
When using a level different from thespecified level, the difference between thereading values of both levels is corrected as∆ Cm :

Fig 2: Reading a meniscus∆ Cm = rU − rL
where

∆ Cm : Difference of density between the upper and lower levels of meniscus (g cm-3)
rU : Reading after the decimal point at the upper level of the meniscus (g cm-3)
rL : Reading after the decimal point at the horizontal level of the meniscus (g cm-3)
Because oil adhering to the neck of the hydrometer influences the measurement, it is necessary
to clean the surface of the neck and body surface with detergent and then degrease them with ethanol
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or acetone. During the measurement, do not touch the neck with bare hands. The temperature of
the hydrometer should be kept at ± 5 °C for the solution to be measured.
When using multiple hydrometers, it is necessary to float them in pure water or a mixed solutionof pure water and sulfuric acid and compare their readings.

In such a case, the density of pure waterρ is determined from the water temperature and that of the mixed solution is determined using apycnometer.
Measure the length of the body the hydrometer ( LB : mm), the length from the upper end of the
body (level at the joint between the body and neck) to the scale of 1.000 ( l1: mm), and length to thescale line 1.050 ( l2 : mm) with a micrometer caliper up to 0.1 mm.
3

In addition, measure the volume

3of the body part of the floating body ( VB : cm ) to 1 cm using a 250 ml graduated cylinder and thecross-sectional area of the 1000 ml sedimentation cylinder ( A : cm2) up to 0.01 cm2.
Based on the measurement results, the effective depth of the center of the body is calculated
from the reading of the decimal part of the hydrometer (Fig.3):

1
V
L = L1 +  LB − B × 102
A
L1 = l1 − 20 (r + ∆Cm )(l1 − l2 )where

L : Effective depth at the center of the float body (mm)L1 : Length from the upper end of the float body to the reading r (mm)l1: Length from the upper end of the float body to reading of 1.000 (mm)l2 : Length from the upper end of the float body to reading of 1.050 (mm)r : Reading of the hydrometer after the decimal point (g cm-3)∆Cm : Difference in density between the upper and lower levels of meniscus (g cm-3)
LB : Length of the body of the hydrometer (mm)
VB : Volume of the body of the hydrometer (cm3)
A : Cross-sectional area of the measuring cylinder (cm2)

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Fig. 3: Calculation of the effective depth at the center of the float body
2-4 Calculation
2-4-1 Calculation of particle size of sediment remaining on the 2 mm sieve by the sieving analysis

The passing mass percentage of the sample remaining on the sieve (nominal mesh size; di ) of 2 mmor larger is calculated by the following equation:2
 Σ m(d )
m0s
i
1 −
 × 100
P (di ) = 0
2
1
3
0
2 
(ms − m0s )m1s m1s + m0s  m0s 

where

di : Nominal mesh size of sieve (mm)P (di ): Passing mass percentage of the sample remaining on a sieve with di of
the nominal mesh size (%)

ms0 : Dry mass of the total sediment sample (g)m1s0 : Mass of sample passed through the 2 mm sieve (g)m10s: Dry mass of the remaining sample on the 2 mm sieve after treatment withwater (g)m0s2 : Dry mass of the remaining sample on the 2 mm sieve after preprocessing (g)m1s3 : Mass of the sample on the 2 mm sieve used for the settling analysis (g)Guideline of ocean observations Vol. 5 Chap. 4 Grain size distribution© Hisashi NARITA, Shigeyoshi OTOSAKA 2018 G504EN:001-020

G504EN-11m(di): Dry mass of the sample remaining on each sieve of nominal mesh size diΣ m(di ): The sum of dry mass m(di) of the sample remaining on sieves of nominal
mesh size ( di ) or larger (g)2-4-2 Calculation of particle size of sediment passed through 2 mm sieve by the settling analysis

During the settling analysis of the sediment sample passing through a 2 mm sieve, the particle size
corresponding to each hydrometer reading is calculated by the following equation:

dR =

18η L
g(ρ s − ρw )T

where

dR : Particle diameter corresponding the reading number R after the decimal pointof the hydrometerη : Viscosity coefficient corresponding temperature tw (°C) of the suspension solution at thetime of the measurement. The η is calculated with the following equation:

η = 0.0017772 − 5.8283 × 10 −5 t w +1.3057 × 10 −6 t w2
−1.847 × 10 −8 t w3 +1.184 × 10 −10 t w4
This equation can be applied to a temperature range from 10 to 40 °C.
g : Gravitational acceleration (cm s-2)

ρs : Average density of particles with a diameter < 2 mm (g cm-3)
ρw : Density of water corresponding to a temperature of the suspension solution (°C)
at the time of the measurement (g cm-3). The ρw is calculated with thefollowing equation.

ρw = 999.84847 × 10 −3 + 6.337563 × 10 −5 t w − 8.523829 × 10 −6 t w2
+ 6.943248 × 10 −8 t w3 − 3.821216 × 10 −10 t w4
This equation can be applied to a temperature range from 5 to 40 °C.

L : Effective depth at the center of the float body (mm)T : Elapsed time from the start of standing of the graduated cylinder to the hydrometerreading (s)The mass percentage of the sample passed through a 2 mm sieve is calculated with the following
equation.
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G504EN-12(m − m )m m V {(R + ∆C + ∆ρ) − ρ }× 100
P (d ) =m(m − m )m m + m
0
s

R

0
s

1
0s

1
0s

3
1s

3
1s

0
1s

0
1s

m

2
0s

w

3
1s

where

P (dR ): Mass percentage of the sample suspended at the time of hydrometer reading(%).

It corresponds to the passing mass percentage.

V : Volume of the suspension solution (1000 mL)∆ρ : Difference in density due to the change in temperature (g cm-3)

2-4-3 Calculation of particle size of sediment remaining on the 75 µm sieve after the settling analysis by the sieving
analysis

The passing mass percentage of the sample remaining on the sieve (nominal mesh size; di ) of 75 µm
or larger after the settling analysis is calculated with the following equation. The size distribution
from 75 µm to 2 mm was generally used for the sieving analysis:

P (di ) = Σ m(d )
m1s4
i
1 −
 × 100
4
0
1
4
0
2 
(ms − m0s )m1s m1s + m0s  m1s 

where

di : Nominal mesh size of sieve (mm)P (di ): Passing mass percentage of the sample remaining on the sieve with di of
the nominal mesh size (%)

ms0 : Dry mass of the total sediment sample (g)m1s0 : Mass of the sample passed through the 2 mm sieve (g)m10s: Dry mass of the remaining sample on the 2 mm sieve after treatment withwater (g)m0s2 : Dry mass of the remaining sample on the 2 mm sieve after preprocessing (g)m1s4 : Mass of the sample on the 75 µm sieve after settling analysis (g)m(di): Dry mass of the sample remaining on each sieve with the nominal mesh size di
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Σ m(di ): The sum of dry mass m(di) of the sample remaining on sieves with nominal
mesh size ( di ) or larger (g)2-5 Evaluation of data

The result of the particle size analysis using the combination of the sieving and the sedimentation
methods (JIS method) is displayed on a semilogarithmic graph with the particle size on the horizontal
axis with the logarithmic scale and the passing mass percentage on the vertical axis. The relationshipis shown as a particle accumulation curve. The particle diameter d (mm) when the passing masspercentage is 10%, 30%, 50%, and 60% is read from the accumulation curve, and the particle diameteris defined as d10 (mm), d30 (mm), d50 (mm) and d60 (mm), respectively. The d10 and d50 iscalled the effective diameter and median diameter, respectively.

Based on these diameters, the'cuniformity coefficient U c and the curvature coefficient U are calculated by the following equation.

Uc =

d60
d10

(d30 )U' =2c

d10 d60

The uniformity coefficient indicates that as the index of the slope of the particle addition curve.
The higher the value, the larger the particle diameter, and the lower value indicates the relatively
uniform particle size. The curvature coefficient is an indicator of the smoothness of the curve.
When the particle size analyzed by the JIS method, the passing mass percentage with respect to theparticle size of less than 75 μm exceeds 100%, and the particle accumulation curve becomes
discontinuous at the junction of sieving analysis and sedimentation analysis (Geotechnical Society ofJapan, 2009).

The reason that the passing mass percentage exceeds 100% is considered to be in highorganic matter content. Such cases can be prevented by facilitating decomposition of organic matterby increasing the concentration of hydrogen peroxide or heating. The discontinuity at the junction ispresumed to be caused by (1) different definition of the particle size between the sieve and thesedimentation analysis, (2) unstable suspension of particles at the initial stage of sedimentation
analysis, and (3) the interaction between particles and the presence of cylinder walls (GeotechnicalSociety of Japan, 2009; Katayama, 1997).

However, since such discontinuity can occur due to analyticalproblems such as insufficient dispersion of samples, it is necessary to replicate the analysis if suchanalytical problems are predicted (Geotechnical Society, 2009).
Although it is necessary to understand the analytical procedure and be proficient, theabove-mentioned causes of the data discontinuity (1) - (3) can be regarded as an essential problem of
the sedimentation analysis. The particle accumulation curve is theoretically continuous and does notexceed 100%. Therefore, if the discontinuity or the degree of passing mass percentage exceeding
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100% is small, the particle accumulation curve is drawn smoothly in accordance with the sieve
analysis. Accordingly, the particle accumulation curve may include the subjectivity of the evaluatorin some cases.
As a method of correcting the discontinuity of sieve and sedimentation analysis, Kumon et lal.
(1992) and Kishi and Kumon (1993) proposed a weight correction method that calculates iteratively
by varying the mass by 0.01 g until the passing percentage at 4.5 ϕ coincided in the both analysis.
Furthermore, in Kumon et lal.. (1992) and Kishi and Kumon (1993), the degree of the weightcorrection is represented by a value obtained by dividing the absolute value of the mass difference
before and after the correction by the sample amount (mass before the correction).

Sawa andNakayama (2014) have proposed an evaluation method that considers synthetic uncertainty andexpanded uncertainty to the results of particle size analysis using sieve analysis and sedimentation
analysis.

3. Measurement of particle size distribution by laser diffraction scattering method
The particle size analysis method (JIS method) which uses the sieve method and sedimentation
method decribed in the previous section has been used as a standard method in in a wide range offields such as civil engineering and geotechnical engineering as well as earth science. However,problems such as length of measurement time, turbulence of suspensions occurring when putting afloat for precipitation analysis, inconsistency of results between the analysts, has been pointed out(Geotechnical Society Japan, 1990).

In addition, the problem of discontinuity near the junction ofsieving method and sedimentation method, which is around 75 μm, may occur, and the correction
method depends on the judgment of the analyst and the evaluator.
In the field of powder process industry and engineering, laser diffraction/scattering method (JIS Z
8825, 2013) and image analysis method (JIS Z 8827-1, 2008; JIS Z 8827-2, 2010) have been applied
to automate grain size measurement. The laser diffraction/scattering method can measure the particle
size of particles with a wide size range of 0.02 to 2000 μm, and it is expected that the method canmeasure particles to which the JIS method is applied rapidly without sieving. Furthermore, in recent
years, it has become possible to measure a wider range of particle sizes by a composit light source
consists of a red laser diode and a blue (405 nm) light emitting diode.

In addition, the laser

diffraction/scattering method has been applied to grain size analysis of geoscientific samples because
it requires less volume of samples and can analyze rapidly than JIS method (Ishii et lal.., 1991;
Nakajima and Kanai, 1996; Saito, 1996; Katayama, 1997; Ando et lal.., 2014; Nishida and Ikehara,2016).
In the laser diffraction/scattering method, the grain size distribution is estimated from concentric
intensity distributions of diffracted and scattered light generated when particles are irradiated withlaser light. The Fraunhofer diffraction theory and the Mie scattering theory are used to correlate thethe pattern of the intensity distribution of the diffracted/scattered light and the particle diameter.
When the grain size is at least 10 times of the wavelength of the laser light, the Fraunhofer diffraction
theory can be applied fot the analysis, and when the grain size is less than about 7 μm (10 times the
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wavelength), the Mie scattering theory is applied because lateral and backward scattering is dominant.
The analysis theory of grain size distribution depends on manufacturer and equipment. Some cases
use Fraunhofer diffraction theory and Mie scattering theory in combination and other case adopt Mie
scattering theory only. The Fraunhofer diffraction theory is one of the approximation of the Miescattering theory, and the algorithm used in the calculation also differs depending on manufacturer andequipment (Tsumura, 1993).
In order to calculate the pattern of the light intensity distribution using Mie scattering theory, it isnecessary to set the refractive index of the solution (dispersion medium) and the suspended particles.
The refractive index (complex refractive index) N p is expressed by the following equation.

N p = n p − kpi
In this equation, the real part n p is the curvature of light, the imaginary kp is the extinction
coefficient, which represents the absorption of light by the particle.

However, in general, theextinction coefficient of the imaginary can be regarded as zero (Kinoshita, 2008). Additionaly, if therefractive index of the solution in which the particles are suspended is n m , the relative refractive
index RRI is expressed by the following equation .

RRI = N p n m
Generally, if particles consist of single component, a literature value of the refractive index isapplied. If the particles are not a single component, a literature value of the main component of theparticle group or a similar substance should be assumed.

However, even if the refractive index is

known, the obtained results of size distributions may differ between equipments (Hayakawa et lal..,1993), and it is considered that the difference is caused by the optical system or refractive index
between the equipments. These issues are black boxed and it is impossible to consider quantitatively(Hayakawa et lal.., 1993). Hayakawa et lal.. (1993; 1995) reported that the refractive index, at which
the median diameter (effective diameter in some cases) based on the particle size distribution of fineceramics shows the maximum, becomes the optimum velue of the device. However, this method is
not effective for bimodal size distributions (Hayakawa et lal.., 1995).
The Mie scattering theory is based on the assumption of complete spherical particles, whereas
most of the particles to be actually measured are aspherical. For this reason, the scattered lightintensity obtained by the laser diffraction/scattering method is affected not only by the particle size but
also by the particle shape. Even if the particles have the same refractive index, the measurement
result will be different if the particle shape is different. The refractive index used in the laser
diffraction / scattering method is not a refractive index as a physical property value but a parameter
specified to the equipment that includes other parameters such as the shape of particles. Therefore, it
should be referred as “refractive index parameter” (Kinoshita, 2000; 2008).
Kinoshita (2008), by inmroving the mehthod of Kinoshita (2000), proposed the optimum refractive
index parameter and its evaluation function that minimizes the residual between the detected light
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intensity distribution and the estimated distribution calculated from the particle size distribution.
However, similar to the method of Hayakawa et lal.. (1993; 1995), the method of Kinoshita (2000;
2008) is also based on the assumption that the particles have uniform size.

Furukawa et lal.. (2000)

introduced an evaluation function that developed the idea of crushing rate for soil particles by Marsal(1965) and Ishii (1985), and proposed to optimize the relative refractive index by changing the value
so that the difference between the particle size distribution obtained by laser diffraction/scattering
method and JIS method to be minimum.

This method is expected to be applied to seabed sediment

composed of various nonspherical particles of minerals. In any case, the setting of the refractive
index in the laser diffraction/scattering method is a big problem for analysts. In recent years, therelative refractive index values of 1.17 to 1.24 are used in particle size analysis of seabed sediments
using the laser diffraction/scattering method (Ando et lal.., 2014; Nishida and Ikihara, 2016).
However, as mentioned above, it is necessary to pay attention that the refractive index is a parameterthat varies depending on the equipment.
In the laser diffraction/scattering method, the particle concentration contained in the dispersion
medium also influences the particle size distribution. In general, the accuracy of the data decreases
when the particle concentration is low (% transmittance is high), and the shift of particle size
distribution to the fine grain side because of the multiple scattering occurs when the concentration ishigh (% transmittance is low). Therefore, an appropriate particle concentration is indicated for eachequipment with the unit of % transmittance.

Furukawa et lal.. (2001) reccomentds that theappropriate % transmittance is 80±5% for laser light, and soil particle concentration is 60±20 mg/100
ml in the dispersion medium.
The maximum diameter that can be measured by the laser diffraction/scattering method varies
depending on the equipment used, and it ranges from 2000 to 5000 μm.

Therefore, when the

maximum particle size of the sample exceeds the measurement range of the equipment, the sample
must be sieved in advance.

On the other hand, when the range of measureable particle size is

between 0.02 and 2000 μm, the ratio of the maximum to the minimum particle size is 105, and it
corresnponds to 1015 in the volume ratio. Therefore, when a particle group having a maximum
diameter of 2000 μm is to be measured, it is necessary to increase the particle concentration in thedispersion medium in order to evaluate the volume of fine particle size appropriately. However, as
described above, since a proper transmittance is required for the accurate measurement, it is necessary
to set the proper maximum grain size for measurement of the laser diffraction/scattering method apartfrom the measurable maximum grain size of the device. Furukawa et lal.. (2001) compared the resultof grain size analysis by the laser diffraction/scattering method and JIS method for a uniform particle
group with different particle sizes and a particle group with different particle size (>38 μm), anddetermined that a proper maximum size for the laser diffraction/scattering analysis is 250 µm. On
the other hand, considering the consistency with the JIS method, grain size analysis by the laser
diffraction/scattering method should be performed for a fraction that passed through a 75 μm or 44 μm
sieve, instead of applying the the maximum particle size of 250 μm (Furukawa et lal.., 2001).
The validity of the result of analyzing the particle size of the seabed sediment by the laser
diffraction/scattering method can only be evaluated by the relative size with reference to the particle
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size distribution obtained by JIS method. Katayama (1997) indicated that the result of the laser
diffraction/scattering analysis for the fraction passing through the 44 μm (4.5 ϕ) sieve was biased tothe coarser grain size compared with that by the JIS sedimentation method, and pointed out that thedifference was mainly due to the principal of measurements. Furthermore, as a problem of thesedimentation method, the influence of the algorithm concerning the particle size calculation of theequipment used, the influence by the algorithm of the particle size calculation of the used equipment,
the influence of the sedimentation And the possibility of the influence of the relative refractive index
used are pointed out.

In addition, it is pointed out that turbulence, interaction between particles anddecline of sedimentation rate due to Brownian motion affect the grain size analysis by sedimentation
method affects. On the other hand, in the laser diffraction/scattering method, the result is influenced
by algorithms for particle size calculation of the equipment used, the relative refractive index and theshape of sediment particles.

Furukawa et lal.. (2001) compare the particle size of soil measured bylaser diffraction/scattering method and JIS method, and pointed out that the result of laser
diffraction/scattering method is biased toward the finer grain compared with JIS method, conversely tothe result of Katayama (1997).

Since the analysis results are influenced by the algorithm of theequipment used, it is difficult to specify the factor that causes the difference between the results.

In

the particle size analysis by the laser diffraction/scattering method, it is necessary to understand thecharcteristics of the equipment through comparison with the JIS method and measurement of areference material.
As mentioned above, both the laser diffraction/scattering method and the JIS method have merits
and demerits regarding the particle size analysis of clay, silt and fine grain sand. Neverthless, incomparison with the JIS method, the laser diffraction/scattering method requires a smaller volume ofsample, enables rapid analysis, and shows high accuracy and reproducibility. These points would be
the greatest advantages in applying the laser diffraction/scattering method to the particle size analysisof the seabed sediment.
3-1 Points of attention in splitting and pretreatment of sediment samples
Even when particle size analysis is performed by the laser diffraction/scattering method, basic
concepts for splitting and pretreatment of sediment sample, described in section 2-5, can be applied.
In this section, some points that should be pay attention in preperation of samples for particle size
analysis by laser diffraction/scattering method.
When the maximum particle size of the sample exceeds the upper limit of the measureable rangeof the equipment, it is necessary to remove the coarse particles by sieving.

In the laser

diffraction/scattering method, the optimum particle concentration in the dispersion medium introduced
into the apparatus is around 60 mg per 100 ml, and the amount is much smaller than that of the JIS
method. Therefore, in order to ensure representation, it is necessary to reduce the sample after
lyophilization by an appropriate method such as a conical quartering. With respect to clay and silt
sediments, considering the consistency with JIS method, the sediment is divided by a 2 mm meshsieve, the fraction passed through the sieve is preprocessed, and used for particle size analysis. As
described in Furukawa et lal.. (2001), in the case of sandy or sand-containing clay and silt sediments,
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it may be necessary to divide the sample further with a sieve such as a 250 μm mesh and use thepassed fraction for the particle size analysis in oreder to avoid biased of particle size distribution due
to the presence of sand. However, the characteristics of the bias may be different depending on theequipment, it is necessary to consider the influence of the sand, necessity of sieving, matching ofsieves to be used in advance of the analysis. In any case, the mass and percentage of particles
remaining in each sieve should be recorded.
Before the particle size analysis of detrital particles in sediment, biogenic carbonates and opals
sample are needed to be removed by dissolution.

During the pretreatment for dissolving thiscarbonate or opal, the lithogenic detritus may also slightly dissolve. Therefore, it is reccomended to
to use an acetic acid-sodium acetate buffer solution (adjusted to pH 5) and 0.1 mol/L sodium
carbonate (Na2CO3) solution to dissolve the carbonate and opal, respectively.
performed for 1 hour at 85 °C.

The reaction is

However, opal may become difficult to decompose with the elapsed

time after sedimentation (Müller and Schneider, 1993). If the dissolution of the opal is insufficient,increase Na2CO3 concentration or extend the reaction time. For dissolution of the biogenic opal, thesolid-liquid ratio is also important in addition to the type and concentration of the alkaline solution andthe reaction time and temperature.

When the solid-liquid ratio is 1 g L-1 or less, silicon dissolves

from clay particles, and dissolution of biogenic opal is insufficient at a higher solid-liquid ratio(Loassachan and Tada, 2008). Terefore, it is necessary to set the solid-liquid ratio to 2±0.5 g L-1 todissolve the biogenic opal. Considering that the proper % transmittance of laser light for grain size
analysis is 80±5%, it is advisable to process 200±50 mg of sediment sample for dissolution ofbiogenic opal.

When replacing the solution during the pretreatment, centrifuge the sample for 10

minutes at 3000 rpm.

Also, after removal of the carbonate, it is necessary to wash the particles withpure water.
Samples after dissolution of the biogenic opal are weighed after lyophilization and the mass of theresidual particles is measured.

Depending on the mass of the residual particles, 0.1% sodium

hexametaphosphate solution is added to the dried sample so that the % transmittance of the laser lightis 80±5%. In the laser diffraction/scattering analysis of the dispersed particles, a circulating flow cellis commonly used. The specifications such as the capacity of the dispersion vessel, flow rate and theultrasonication option differs between the apparatus. Therefore, it is necessary to investigate theinfluence of the measurement time on the results in advance of the sample analysis, and theappropriate time parameters should be determined according to the required accuracy.

Blankmeasurement with 0.1% sodium hexametaphosphate solution containing no particles should be
performed under the same conditions as the sample measurement.
For analyzing the size distribution of particles with large particle size excluded when used for laser
diffraction/scattering analysis, methods described in sections 2-2 and 2-3-3 are applied. However, it
is sometimes impossible to precisely measure the particle size distribution because of the lack ofsample mass of the particles remaining in the sieve. Therefore, the measurement of grain size ofsuch particles remained on the sieve should be performed independently from the laser
diffraction/scattering analysis. In the field of earth science, particle size distribution measurement
using a digital image analysis device is being introduced in recent years, and the measurable size range
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is 30 μm to 30 mm (Nanayama et lal.., 2012). The digital image analysis also has an advantage thatit can be measure the major axis diameter, the minor axis diameter. It will be an effective tool forevaluating the continuity of results by sieving analysis, sedimentation analysis or laser
diffraction/scattering analysis.

References
Kitano, Y. (1972): Senkai Taisekibutu: Taisekibutu no Kagaku (Shallow water sediments: Chemistry of
sediments), ed. Y. Miyake, Tokai Univ. Press., 243-335.
Terashima, S., N. Imai, K. Ikehara, H. Katayama, T. Okai, M. (Ujiie) Mikoshiba, A. Ohta and R. Kubota (2008):
Variation of elemental concentrations of river and marine sediments according to the grain size classification.
Bull. Geol. Surv. Japan, 59 (9/10), 439-459.
JIS A 1204, Test method for particle size distribution of soils, Japanese Standard Association, Tokyo, (2009).
JGS 0051, Method of classification of geomaterials for engineering purposes, Japanese Deotecgnical SocietyStandards, Tokyo, (2009).
Wentworth, C.K. (1922): Method of computing mechanical composition of sediments. Geological Society ofAmerica Bulletin, 40, 771-790.
Ohkubo, T. (1989): Comparison of size distribution measured by serveral methods. Bill. Yamagata Univ. (Eng.),
20 (2), 159-168.
Jackson, M.L. (1956): Soil chemical analysis: advanced course: Published by the author,. Madison, Wis., 895 p.
DeMaster, D.J. (1981): The supply and accumulation of Silica in the marine environment. Geochimi.
Cosmochimi. Acta, 45, 1715-1732.
JIS B 7525-1, Density fydrometers, Japanese Standard Association, Tokyo, (2013).
The Geotechnical Sciety of Japan (2009): Test meshods of ground materials, The Geotechnical Sciety of Japan,
Tokyo, 533 p.
Katayama, H. (1997): Comparison between a lazer diffraction-scattering method and a hydrometer method in thegrain size analysis for fine-grained sediments. J Sedimentological Soc. Japan, 46, 23-30.
Kumon, F., T. Kamittani, K. Sutoh, Y. Inouchi (1992):

Grain Size Distribution of the Surface Sediments in

Lake Biwa, Japan. Mem Geol Sco Japan, 39, 53-60 (in Japanese)
Kishi, S., F. Kumon (1993): Grain-size analysis combined settling tube method with hydrometer method for
muddy sand sediments. Journal of the Sedimentological Soc. Japan, 38, 101-106.
K. Swa, Y. Nakayama (2014): A study on the evaluation of the uncertainty of particle size distribution test
results. Japan Geotechnol. J., 9, 255-274.
JIS Z 8825, Particle size analysis-Laser diffraction methods, Japanese Standard Association, Tokyo (2013).
JIS 8827-1, Particle size analysis Image analysis methodsPart 1 : Static image analysis methods, JapaneseStandard Association, Tokyo (2008).
JIS 8827-2, Particle size analysis-Image analysis methods-Part 2: Dynamic image analysis methods, JapaneseStandard Association, Tokyo (2010).
The Geotechnical Sciety of Japan (2009): Test meshods of soils, The Geotech. Soc. Japan, Tokyo, 902 p.
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Ishii, J., T. Yabuta, T. Maeda (1991):

Grain size of a core sample from the northern Japan Basin, analyzed by alaser-beam diffravtion method. Proc. Hokkaido Tokai Univ. Sci. Eng., 4, 9-25. (in Japanese)
K. Nakajima, Y. Watanabe (1995): Recurrence Intervals of earthquakes inferred from turbidites near the
Epicentral area of the 1983 Japan Sea Earthquake. J. Seismolog. Soc. Japan. 2nd ser., 48, 223-228.
Saito, Y. (1996): Grain-size and sediment-color variations of Pleistocene slope sediments off New Jersey. In
Mountain, G.S., Miller, K.G., Blum, P., Poag, C.W. and Twichel, D.C. eds., Pro- ceedings of the Ocean
Drilling Program, Scientific Results, 150, 229-239.
Ando, H, M. Oyama, F. Nanayama (2014): Data report: grain size distribution of Miocene successions, IODP
Expedition 313 Sites M0027, M0028, and M0029, New Jersey shallow shelf.
McInroy, D., Cotterill, C., and the Expedition 313 Scientists,

In Mountain, G., Proust, J.-N.,

Proceedings of the Integrated Ocean Drilling

Program, 313.
N. Nishida, K. Ikehara (2016):

Spatial variation of coastal marine sediments of the northern Suruga Bay,central Japan and their depositional processes. Seamless Geoinformation of Coastal Zone S-5, 1-23.
Tomura, S. (1993): Particle-Size Analysis of Clays. J. Clay Sci. Soc. Japan, 32, 239-246. (in Japanese)
Hayakawa, O., K. Nakahara, J. Tsubaki (1993):

Estimation of the optimum refractive index by laser diffraction

and scattering method. J. Soc. Powder Technol. Japan, 30, 652-659. (in Japanese with Einglish abstract)
Hayakawa, O., Y. Yasuda, M. Naito, J. Tsubaki (1995): The effect of the refractive Index Input value onparticle size distribution measured by the laser diffraction & scattering Method. J. Soc. Powder Technol.
Japan, 32, 796-803. (in Japanese with Einglish abstract)
Kinoshita, T. (2000): The method to determine the optimum refractive index parameter in laser diffraction andscattering methods. J. Soc. Powder Technol. Japan, 37, 354-361. (in Japanese with Einglish abstract)
Kinoshita, T. (2008): An investigation of evaluation function for the method to determine the optimum
refractive index parameter in laser diffraction and scattering method J. Soc. Powder Technol., Japan, 45,
104-109. (in Japanese with Einglish abstract)
Marsal, R.J. (1965): Soil properties-shear strength and consoidation. Proc. , 6th, ICSMFE, 310-316.
Ishii, T. (1989): Physical Significance of Indices for Particle Breakage. Soils and Foundations, 29, 155-164
Furukawa, Y., T. Fujita, T. Kunihiro, M. Fukazawa (2000): Investigation of particle size distribution of soil
using a particle size analysis equipment automated by laser and its applicability to soil samples.

Trans.

Japan Soc. Civil Eng., 687, 219-231. (in Japanese)
Müller, P.J. and R. Schneider (1993):

Anautomated leaching method for the determination of opal in sediments

and particulatemater. Dep-Sea Res., 40, 42-54.
Loassachan, N. and K. Tada (2008):

Effect of solid to solution ratio on biogenic silica determination in coastal

sediments. J. Oceanogr., 64, 657-662.
Nanayama, F., R. Furukawa, M. Ogasawara (2013): How to measure the particle size in sediment? : a planning
the sophistication of the equipment and the data integration system of grain size analysis. GSJ Chishitsu
News, 2, 82-85. (in Japanese)

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Major component○Hisashi NARITA (Tokai University), Shigeyoshi OTOSAKA (The University of Tokyo)

As seabed sediment reflects geochemical cycles and the sedimentary environment, the sedimentation
rate, particle size and biochemical/mineralogical composition of sediments vary greatly.

Therefore,

the major composition of sediment provies important information for understanding geochemical cycles
and the sedimentary environment in the study area.
Seabed sediment is generally composed of lithogenic, biogenic, or authigenic mateirals.
Lithogenic matter originates from terrestrial rocks, and consists of minerals transported through rivers
and the atmosphere.
and carbonates.
organisms.

Biogenic material is generally divided into three groups: organic matter, silicates,

Organic matter can be further divided into terrestrial (mainly plants) and aquatic

Biogenic silicate is mainly produced by phytoplankton in seawater, and is an amorphoussilicate (biogenic opal) formed from silicic acid in seawater.

Skeletons of diatoms are a typicalbiogenic opal, and this subatance is also produced by siliceous dinoflagellates, radiolarians, and sponges.
Biogenic carbonates in the marine environment are produced by coccolithophores, foraminifera,
shellfish, and coral.

Seabed sediment also contains small amounts of terrestrial carbonate.

For

example, large amount of carbonate is contained in soil at the source area of eolian dust (kosa) (Quan etal., 1994).

Minerals of aqueous origin from non-biologically (inorganically) from dissolved materials

in water, and the minerals that form in the seawater or sediments are generally called authigenic minerals.
Authigenic minerals include oxides such as those of Fe and Mn, sulfates, sulfides, phosphates, andcarbonates.
Among these substances, lithogenic matter, biogenic opal, biogenic carbonate and organic matterare particularly important as major components of sediment.

In some cases, authigenic minerals suchas Fe and Mn oxides are present in significant proportions in sediments.

This chapter describes anoutline and points of attention in analyzing the amounts of lithogenic matter, biogenic opal, biogenic
carbonate, and organic matter, which mainly contribute to the composition of sediment.
1.

Sediment sampling
For the purpose of analyzing the major components of sediments, sediment samplers such as grab

samplers, multiple corers, gravity corers, and piston corers are commonly used.

In particular, whenanalyzing surface sediments, it is recommended to use a multiple corer that minimises disturbance ofthe sediment surface and can collect water overlying the sediment.

Please see Chapter 1 of this volume

for details on sediment sampling.
2.

Pretreamenr of sediment samples
After drying a sediment sample, the size of the sample is reduced by the increment method (JIS Z

8816, 2001) in principle. However, for sediments consisting of fine particles, there is practically no
problem if the sample is sorted an appropriate amount arbitrarily. Gravel, shell pieces, and plant andanimal material are removed with a sieve before analysis.
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Drying of the sediment sample should be carried out by freeze-drying.

It is recommended to avoid

heat drying as fine grains aggregate during heating and coarse lithogenic particles may be unnecessarily
crushed by grinding.

Freeze-dried sediment particles are easily dispersed and the loss of coarse

particles due to breakage is relatively small.

It is possible to calculate water content by measuring themass of the sediment before and after drying (see Chapter 2 for details).

An electronic balance thatcan read to 1 mg should be used for weighing.
After drying, the sediment sample is sieved with a 2 mm (9 mesh) sieve.

During sieving, fineparticles on the surfaces of coarse particles should be separated as much as possible.
as gravel and shell fragments should be removed by hand picking.

Impurities such

After being passed through the 2

mm sieve, the sediment sample is passed through a 0.180 mm (80 mesh) sieve.

Particles on the 0.180

mm sieve (with particle size btween 0.180 and 2 mm) are gently crushed in an agate mortar so that theparticles pass through the sieve.

With regard to particles passed through the 0.180 mm sieve, no further

grinding is required because there is no significant influence from grinding (Imai, 2010) and Si inlithogenic matter may be desorbed from finely ground sediment during analysis of biogenic opal
(Mortlock and Froelich, 1989).
For the measurement of major components in seabed sediment, samples passed through a 0.180 mm
sieve are used.

Except for samples obtained in certain sea areas such as estuaries and coasts, coarse

sediments of 2 mm or more, such as gravels and shell fragments, should not be used for analysis because
they are less representative.
3.

Lithogenic and authigenic matter
There are two ways to estimate the amount of lithogenic matter (% LM).

In the first method,concentrations of biogenic opal (% BO), CaCO3 (% CC), and organic matter (% OM) are measured by
the following method, and the sum of the three biogenic components (% TB) is subtracted from 100 %(e.g., Nederbragt et al., 2008).

%LM = 100 − (%BO +%CC + %OM)
= 100 − % TB

The concentration of organic matter (% OM) is estimated from the organic carbon content (% TOC)

by the following equation (Nederbragt et al, 2008).

%OM = 2.2  % TOC
The accuracy of the lithogenic matter content estimated by this method is determined based on the
propagation of the measurement accuracy of biogenic opal, CaCO3 and organic matter concentrations

as follows:

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LM =100 − % TB
% TB

( +  +  )
2
BO

2
CC

2
OM

 The second method is to calculate lithogenic matter content (% LM) from Al concentration in thesediment sample (% Alsample), assuming the average crustal composition ratio (% Alcrust; e.g., Taylor,1964).

This method is widely used for estimating the amount of lithogenic matter content in sinking

particles collected by sediment traps (e.g, Noriki and Tsunogai, 1985).

%LM =% Al sample% Al crust

 100

It is difficult to estimate the proportion of authigenic minerals in sediments from elemental


composition alone, but the concentration coefficient (EFM; “M” indicates any element of interest) of anelement in the sediment against the crustal abundance and excessive concentration of the element
relative to the crust [Mexcess] are commonly used as indicators. These indicators are calculated using
the following equation (Ravichandran et al., 1995):

EFM =



(M Al)sample(M Al)crustM excess sample = Msample − (M Al)crust  Alsample

where [M] sample is the total concentration of the element of interest in the sediment, (M/Al)sample and
(M/Al)
crust are the ratio of the element of interest and Al in the sediment sample and the average in thecrust, and [Al]sample is the Al concentration in the sediment sample.

This method is based on theassumption that the majority of Al in the sediment is of crustal origin.
In estimating such concentration factors and excess concentrations, it is important to carefully selectthe (M/Al)crust values used for calculation (Turekian and Wedepohl, 1961; Taylor, 1964; Taylor and
McLennan, 1985).

For example, in estimating excess Ba concentration ([Baexcess]sample), 0.005 to 0.01

is used as the value of the Ba/Al ratio in terrestrial crust, and this range in the Ba/Al ratio causes deviationof up to 50 % (Reitz et al., 2004).

In some cases, (Ba/Al)crust is assumed to be similaer to Ba/Al ratio

in the residue after removing authigenic Ba from the sediment sample by the selective sequential
dissolution method (Schenau et al. 2001) (Reitz et al., 2004).

In addition, because [Alexcess]sample issometimes observed from sinking particles, Ti, which has a short residence time in surface seawater, isused as an indicator of representative lithogenic element (Dymond et al., 1997).

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3-1 Determination of elemental composition of sediment
For determination of major elemental composition of sediment samples, X-ray fluorescence analysis
is commonly used.

In this analysis, a powdered sediment sample and lithium tetraborate are mixed at

a ratio of 1:5 to 1:10 and melted at 1100 °C in an Au-Pt alloy crucible to prepare a glass bead for analysis.
In general, about 1 g of sediment samples is required for this analysis.

With this method, in addition

to major elements such as Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, and P, the trace elements such as V, Cr,
Co, Ni , Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, Th, and As can be measured.

For the quantitative

determination of elements, several standard materials are measured, and a calibration curve based on
the relationship between the intensity of X-ray fluorescent and the elemental composition of the standard
is prepared in advance (e.g., Hokanishi et al., 2015).
There is also a method in which the sediment sample is dissolved with HNO3-HClO4-HF and major
elements are measured with MP-AES and ICP-AES/ICP-OES or ICP-MS.

Because of the sensitivityof these instruments, only about 0.1 to 0.2 g of each sediment sample is required for the analysis.

In

addition, by combining ICP-MS with MP-AES or ICP-AES/ICP-OES, it is possible to quantify traceelements such as rare earth elements, Sc, and Th. Although decomposition using HF is unsuitable formeasurement of Si, it is possible to measure Si by the acid decomposition method using a sealed Teflon
vessel combined with calorimetric spectrophotometry (Noriki et al., 1980).

In determination ofelements, an absolute calibration curve with an added internal standard is used.

For an internal

standard, In (indium) is used for the MP-AES and ICP-AES/ICP-OES methods.

For the ICP-MS

method, in addition to In-115, isotopes such as Be-9 and Tl-205 are used for measurements of low andhigh mass elements, respectively.

The internal standards are added such that the concentration is thesame for a series of samples and standard solutions.

The concentration of an element used as theinternal standard should be 100 times or more than the concentration of the element in the sample
solution.

In addition, it is recommended to analyze a certified reference sample such as JMS-1, JMS-

2, or JLk-1 of the National Institute of Advanced Industrial Science and Technology (AIST), or SRM
2702 or SRM 2703 of the National Institute of Standards and Technology (NIST), simultaneously withthe sediment sample.

In preparation of the standard and internal standard solution and preprocessingof the sample, reagents of a high purity grade should be used, depending on the concentration of thetarget component in the sample.
3-2 Decomposition of sediment sample by mixed acid
To completely dissolve the sediment sample, it is necessary to decompose the carbonate, biogenic
opal, aluminosilicates, and organic matter contained in the sample.

In the past, the alkaline melting

method (heating a sample together with Na2CO3 and then dissolving it in an acid) was commonly used.
As analytical methods using MP-AES, ICP-AES/ICP-OES, or ICP-MS has now become popular, anddecomposition of sediment samples in sealed Teflon vessels with mixed acid containing HF followedby simultaneous measurements of multiple elements is becoming mainstream.

Because only a small

amount of acid is used for decomposition, the use of sealed Teflon vessels can reduce reagent blanks
and avoid contamination.

As mixed acid, HNO3-HClO4-HF or HClO4-HF is generally used.

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However, in the decomposition of samples containing aluminosilicates (i.e., seabed sediment) using HF,
fluorides such as insoluble CaAlF5 and CaMg2Al2F12 are produced during decomposition.

These

fluorides may limit precise analysis of trace elements such as Rb, Sr, Y, Cs, Ba, REE, Pb, Th, and U
due to coprecipitation with the fluorides (Yokoyama et al., 1999). Therefore, it is necessary to dissolve
the generated fluoride and moderately adjust the solution for the measurement.
To dissolve fluorides, a boric acid solution is added directly to the decomposed solution and diluted
to a certain volume.

Alternatively, the solution after decomposition is once evaporated in a Teflon

beaker, the dried residue is dissolved with 5 %~10 % HNO3 followed by the addition of a certain amountof boric acid solution and then dilution to a certain volume.

The addition of boric acid promotes

dissolution of fluoride and is also effective in masking excess HF.

However, in adding boric acid, caremust be taken because measurement sensitivity and sensitivity drift may occur when analyzing by ICPAES/ICP-OES or ICP-MS because of the increase of matrix.
According to the method of Yokoyama et al. (1999), sediment samples are dissolved with a HClO4HF solution, the solution is gradually heated to completely evaporate to dryness, and 1 ml of 7 M HClO4
is added to the residue, which is then heated to completely evaporate to dryness.
excess HF is completely removed and all fluorides transform to oxide.

By this method,

By dissolving the residue with

HCl, evaporating again to dryness, and dissolving in 4 M HNO3 solution, it is possible to recover nearly
100 % of the trace elements without coprecipitation with fluoride.
4.

Biogenic opal
Opal is an amorphous silicate, and that formed by plankton is called biogenic opal. Biogenic opals

are distinguished from volcanic amorphous aluminosilicates (volcanic glass).

Diatoms, siliceous

dinoflagellates, Parmales, radiolarians, and sponges are known produceers of biogenic opal.

In

particular, diatoms and Parmales occupy an significant proportion of the community composition ofphytoplankton in the subarctic North Pacific (Komuro et al., 2005).

Diatoms and radiolarians can befound in deep-sea sediments and have been used as indicators in stratigraphic and paleoceanographic
studies based on their assemblages.

In addition, from the vertical change in biogenic opal content insediment, it is possible to reconstruct past changes in primary production in the ocean (e.g., Narita et al.,2002).
The alkaline extraction method is commonly used for quantitative analysis of biogenic opal in
sediments.

However, in this method, dissolution of coexisting clay minerals occurs in addition toelution of Si from biogenic opal (e.g., DeMaster, 1981) .

Generally, desorption of Si from clay

minerals increases in the order of illite < montmorillonite < kaolinite (Kamatani and Oku, 2000).

Such

desorption of Si is more remarkable with NaOH solution than Na2CO3 solution.

Desorption of Si fromsediment tends to increase with increasing concentration of alkaline solution.

In addition, amorphousclay minerals such as allophane tend to release Si more quickly than kaolinite (Kamatani and Oku, 2000).
At this time, the type and concentration of alkaline solution, dissolution temperature, and time for themeasurement of biogenic opal in sediments haves not yet been unified (Conley, 1998).
The methods of DeMaster (1981) and Mortlock and Froelich (1989) are widely used for analysis of
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biogenic opal in seabed sediment.

The difference between the two methods is whether the amount ofdissolved Si from clay minerals, including volcanic glasses, is corrected.

DeMaster (1981) dissolved

Si in the sediment using a 1 % (0.1 M) Na2CO3 solution, and assumed that the temporal change of the
Si concentration in the extract consisted of two different dissolution curves, for biogenic opal-derived
Si (fast dissolution) and mineral-derived Si (slow dissolution).

In this method, an intercept obtained

from the approximate line of the Si dissolution curve after a sufficient time has been defined asconcentration of biogenic opal-derived Si (time step method).
In contrast, Mortlock and Froelich (1989) recommend using a 2 M Na2CO3 solution and to heat
uniformly for 5 hours at 85 °C to dissolve Si from biogenic opal. They reported that the contributionof Si dissolved from clay minerals was about 2 % to 3 %. Accordingly, this is a very advantageous
method for measuring biogenic opal in many samples.

However, dissolution of opal in radiolarians

and sponge spicules is insufficient under these conditions (Mortlock and Froelich, 1998; Lyle and Lyle,
2002).

There is also a method of correcting the contribution of dissolved Si from aluminosilicatesusing Al concentration eluted in alkaline solution (Kamatani and Oku, 2000).
unsuitable for measurement of a large number of samples.

This method is

In addition, Shimesh et al. (1988) reported

that dissolution of Si from clay minerals is not related to clay content or the clay/opal ratio in sediment.
Most of the biogenic opal in seabed sediment is derived from diatom, the primary producers (Nelson
et al., 1995). With this in mind, this section compares the method of DeMaster (1981) with the methodof Mortlock and Froelich (1989) which is advantageous for analysis of biogenic opal of a large numberof samples, and describe points to notice when analyzing biogenic opal.
4-1 Weighing sample mass
The content of biogenic opal in sediment greatly varies spatiotemporally.

Therefore, whenmeasuring the biogenic opal content, it is necessary to predict the biogenic opal content in advance andto adjust Si concentration in the measurement solution at the final step of the measurement.
According to DeMaster (1981), 10 to 30 mg of dried sediment is precisely weighed into a 50 ml
polypropylene centrifuge tube, and 50 ml of 1 % (0.1 M) Na2CO3 solution previously heated to 85 °C isthen added to dissolve biogenic opal. According to Mortlock and Froelich (1989), 25 to 200 mg ofdried sediment is used, and 40 ml of 2 M Na2CO3 solution is added after the pretreatment described
below.

In these two methods, the ratio of sediment to the amount of alkaline solution (solid-liquidratio) differs by one order of magnitude.

In the former case, the solid-liquid ratio, is in the range of-1

0.2 to 0.6 g L , and in the latter case, it is in the range of 0.63 to 5.0 g L-1.
Although the solid-liquid ratio is an important factor when quantifying biogenic opal content byalkaline extraction using solid-liquid equilibrium, few studies have considered this quantitative
relationship.

Loassachan and Tada (2008) extracted Si by a time step method after the method of

DeMaster (1981) with different solid-liquid ratios, and investigated the influence of the solid-liquid ratioon the recovery of biogenic opal.

In addition, Lyle and Lyle (2002) examined the effect of extractionof biogenic opal by comparing two types of alkaline solutions, 2 M Na2CO3 and 2 M KOH.
-1

They

found that in the range of the solid-liquid ratio of 1.1 to 2.4 g L , when the solid-liquid ratio is small,
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opal of biological origin is overestimated due to promotion of the elution of Si from clay minerals, andwhen the solid-liquid ratio is high, dissolution of Si is suppressed and leads to underestimation ofbiogenic opal.

However, it should be noted that the solid-liquid ratio described here is “the ratio of theamount of sediment particles excluding organic matter and CaCO3 to the amount of the alkaline
solution”. Generally, the influence of organic matter content on the solid-liquid ratio in the extractionof biogenic opal is relatively small.

However, when analyzing samples with high or variable CaCO3

content, it is recommended to analyze biogenic opal content after determined CaCO3 content.
Strictly speaking, the solid-liquid ratio applied to opal analysis needs to account for the type andconcentration of the alkaline solution to be used, the reaction time, and the mineral composition oflithogenic matter in the sediment.

Prior to analyzing biogenic opal in a sediment sample, it ispreferable to conduct a preliminary experiment using a working standard or the sample to confirm thelinear relationship between the sample amount and the extracted Si concentration.
For the biogenic opal analysis, dried sediment is precisely weighed with a balance that can measure
to 0.1 mg.

It should be noted that samples with high organic content may absorb moisture under a highhumidity conditions.

It is recommend to use a weighing dish made of non-electrified polystyrene. A

boat-shaped weighing dish with sharp edges is helpful for transferring the sample to a centrifuge tube
with a small amount of pure water.
with 0.1 ml precision.

In addition, it is necessary to add the alkaline solution to the sample

As an alkaline solution such as 2 M Na2CO3 has high viscosity, it may resultsin low reproducibility when measuring the volume using a volumetric devise such as an automatic
pipette.

For this reason, measurement of the amount of alkaline solution and dilution for determinationof sample and standard solutions are carried out on the basis of the mass.
4-2 Sample pretreatment
Mortlock and Froelich (1989) processes sample for biogenic opal determination to remove inorganic
substances (oxides and sulfides) and organic matter covering the surfaces of biogenic opal with 10 %H2O2 and 1 M HCl.

DeMaster (1981) did not carry out such pretreatment.

Pretreatment with H2O2 and HCl is a method widely used in the field of microscopic analysis ofdiatoms.

Such pretreatment is effective for removing sulfide (Akiba et al., 2014) and oxides formedon the surface or inside diatoms’ frustules as well as in fecal pellets in coastal sediment.

Nevertheless,few studies have examined the influence of this pretreatment on the quantitative analysis of biogenic
opal (e.g., Michalopoulos and Aller, 2004).

This process should be avoided as pretreatment has beenfound to be unnecessary, based on the fact that there is no significant difference in the results between
those of Mortlock and Froelich (1989) and DeMaster (1981) (Conley, 1998).
During pretreatment, sediment particles must not be lost.

For samples with large amounts oforganic matter and CaCO3, the reaction proceeds rapidly when H2O2 or HCl is added, or a substancesuch as manganese oxide in the sample acts as a catalyst to decompose H2O2, whereby the solution isejected from the reaction vessel (centrifuge tube), and the sample may be lost in some cases.

To avoidsuch problems, after the sample is swollen with a small amount of pure water, a further 4 ml of purewater should be added, and 2 mL of 30 % H2O2 should be dropped into the smple while confirming the
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state of the reaction.

The centrifuge tube is allowed to stand for 12 hours or more to decompose theorganic matter and then heated in an oil bath for 60 minutes to promote decomposition of H2O2.

In

this process, when the centrifuge tube is sealed, internal pressure rises because of the generated gas, andthe centrifuge tube may rupture.

Therefore, a pinhole is opened in the cap of the centrifuge tube

(Mortlock and Froelich, 1989), and when the sample is left and heated, the cap should be closed loosely.
After the tube is allowed to cool, 5 mL of 1 M HCl should be dropped in while the state of the reaction
is checked.

After confirming the dissolution of CaCO3, pure water is added to make the total volume

40 ml; the sample is then centrifuged at 3000 rpm (about 1500 g) for 10 minutes, and the supernatantsolution is removed.

Then, 40 ml of pure water is added, the deposit is resuspended, the sample iscentrifuged at 3000 rpm (about 1500 g) for 10 minutes, and the supernatant solution is removed.
this stage, the solution becomes almost neutral.

The deposit is dried in a vacuum freeze dryer.

At
Heat

drying should be avoided as it promotes agglomeration of the particles and prevents the particles fromdispersing in the alkaline solution.

For this reason, vacuum freeze drying is recommended.

4-3 Extraction conditions
The recommended conditions for extraction of biogenic opal from sediments differ greatly between
scientists (Conley, 1998).

The extraction of Si from sinking particles and cultivated diatoms can becompleted in 20 to 30 minutes even with 1 % (0.1 M) Na2CO3 solution and it does not depend on thetype or concentration of alkaline solution or processing time (Müller and Schneider, 1993; Kamatani
and Oku, 2000).

However, for extraction of Si from diatom fossils such as those of Pliocene age anddiatomaceous earth, a longer processing time is required, and Na2CO3 solution may be insufficient(Müller and Schneider, 1993; Kamatani and Oku, 2000).

Also, for radiolarians and sponge spicules,

the processing time tends to increase compared that needed for diatom frustules or diatom shells, anddissolution may be insufficient even with 0.1 M NaOH solution (Müller and Schneider, 1993).

Indeed,Mortlock and Froelich (1989) pointed out that dissolution of Si from radiolarians may be insufficient
after 5 hours of treatment at 85 °C with 2 M Na2CO3 solution. Furthermore, Lyle and Lyle (2002)
showed that dissolution of biogenic opal from sediments rich in radiolarians from the Miocene andEocene was insufficient after processing with 2 M Na2CO3 solution, and recommended using 2 M KOH
solution.

However, except for some regions where radiolarian mud accumulates, such as the equatorial

Pacific, the contribution of radiolarian-derived opal to total biogenic opal is ~ 2 % (Mortlock andFroelich, 1989).

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4-4 Measurement conditions
Spectrophotometric analysis is commonly used for determination of dissolved Si in an alkaline
solution, and sometimes it is measured with ICP-AES.

In this section, points for determination of Si

by the spectrophotometry are described.
The molybdenum blue and molybdenum
yellow

methods

areavailable

spectrophotometric analysis of Si.

for

Table 1

Table 1: Calculated Si concentration in 40mL of 2
M Na2CO3 solution extracted from 100 mg of
sediments containing several kinds of biogenic opal
content.

shows calculated Si concentration in 2 M Na2CO3
solution extracted from 100 mg of sediments
containing several kinds of biogenic opal.

In

addition, Fig. 1 shows typical calibration curves
from the molybdenum blue and molybdenum
yellow methods using a 1 cm cell.
The molybdenum blue method has a highmolecular absorptivity at a wavelength of 810 nmof 1.9×104 L mol-1 cm-1 and a dynamic range ofabout 0 to 60 μmol L-1 in the case of using a 1 cm
cell. Therefore, for the determination of biogenic
opal using the molybdenum blue method, it isnecessary to dilute the alkaline solution by about
40 for analysis of a sample with opal content of
5 %.

When the opal content in the sample is

50 %, it is necessary to dilute the alkaline solution
by about 400 times.

In the molybdenum yellow

method, the molecular absorptivity is 2.8×103 L
mol-1 cm-1 at a wavelength of 385 nm, and 2.1×103
L mol-1 cm-1 at a wavelength of 400 nm.

Thismethod has a wider dynamic range than that of themolybdenum blue method and is suitable fordetermination of high concentration of Si.

Fig1: Examples of calibration curves using

The molybdenum blue method and molybdenum yellow

quantitative range when a 1 cm cell is used is from method.
0 to 400 μmol L-1 at 385 nm, and from 0 to 600 μmol L-1 at 400 nm.

Therefore, when we apply awavelength of 400 nm for measurement, Si can be measured for all sediment samples with biogenic opal
content up to 75% by diluting the extracted alkaline solution by 50 times.

Thus, the molybdenum

yellow method is advantageous for quantitative determination of wide range of biogenic opals in
sediments.

However, fading is faster with the molybdenum yellow meyhod than with the molybdenum

blue method, and it is necessary to measure with in 10 to 30 minutes after colouring is performed.

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4-5 Calculation of biogenic opal content
Because biogenic opal contains ~15 % water molecules in its crystal, the existence of water cannot
be ignored when considering the composition of the sediment.

Mortlock and Froelich (1989) proposedthat the chemical formula of biogenic opal in sediment is SiO2 ∙ 0.4H2O and that the molar mass is 67.3.
The formula for determining the amount of biogenic opal (%BO)

in the sediment from the Siconcentration in a diluted alkaline solution is shown below:%BO =Cdilu  10 −3  w dilu w div  w alk  67.3  10 −6
 100
w sed

where,






5.

Cdilu
wdilu
w div
w alk

: Si concentration in diluted alkaline solution (µmmol kg-1): Mass of diluted alkaline solution (g): Mass of dispensed Na2CO3 solution before dilution (g)67.3: Mass of Na2CO3 solution used for extraction of biogenic opal (g): Molar mass of biogenic opal (g mol-1)

w sed: Mass of sediment sample used for analysis (g)Calcium carbonate (CaCO3)


CaCO3 in the sediment is classified into material of terrestrial origin and of biological origin. The
former is derived from rivers and atmospheric dust represented by kosa, whereas the latter is producedby coccolithophore and foraminifera.

In the North Pacific, CaCO3 is dissolved in the deep sea wherewater depth exceeds 3000 m, and it can be measured from sediment in the shelf area, continental slope,or seamounts at depths of ~2500 m. Coccolithophores and foraminifera, like diatoms and radiolarians,
have been used as stratigraphic and palaeoceanographic proxiesy based on fossil assemblages.

Inaddition, from vertical changes in the CaCO3 content of seabed sediments, fluctuation of past primary
production in the ocean can be reconstructed.
There are two main methods of analyzing CaCO3 in sediment.

In the first method, CaCO3 content

is obtained from the difference between the total carbon amount and the organic carbon amountmeasured by a CHN analyzer, and the second method it to quantify the generated CO 2 based on the
coulometric titration after acid is added to the sample.

As the pretreatment line differs according to its

design philosophy, in this chapter, we only describe the points to be noted for CaCO3 determination
based on coulometric titration.

Guidelines for handling the coulometric titrator and calibration methodof the equipment are provided by Dickson et al. (2007).
5-1 Samples and weighing sample mass
The content of CaCO3 in the sediment varies spatiotemporally.

In the coulometric titration method,

if a large amount of CO2 is introduced into the apparatus in a short time, the temperature of the
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electrolytic cell increases considerably.

In such a case, the dissociation constant of the pH indicatorused in the catholyte solution is changed, and the detection sensitivity at the end point of the titration
varies for each calibration and sample.

Therefore, it is important to minimise the change in temperatureof the electrolysis cell between measurements as much as possible, and for that purpose, it is necessary
to change the amount of sample to be measured according to the CaCO3 content.
Dickson et al. (2007) recommends replacing the cell solution when the cumulative amount of CO2
introduced into the electrolysis cell reaches 2 mmol, or if 12 hours have elapsed after the firstmeasurement.

If measuring CaCO3 using 25 mg of a sample containing 25 % of CaCO3, 30 samples

can be measured with one cell adjustment.

The number of samples is 10 when measuring with 25 mgof sample containing 75 % of CaCO3. Therefore, when measuring a sample with 75 % CaCO3 content,
the sample amount should be reduced to about 10 mg.

In this case, about 25 samples can be measured

within the constraint of 2 mmol.
Dry sediment samples to be analyzed are precisely weighed with a semi-microbalance capable ofmeasuring to 0.01 mg or with a microbalance capable of measuring to 0.001 mg.

Samples with highcontents of organic matter absorb moisture during weighing and may increase in mass.

Therefore,

when weighing, attention should be paid to control the humidity and temperature of the atmosphere.
The balance should be installed under conditions of 45 %~60 % relative humidity and 20 °C ~25 °C
temperature.

However, when the relative humidity becomes 45 % or less, caution is required because

the substance becomes easy to charge, measurement error is caused by the generated static electricity,and the balance display becomes unstable.
Recently, a balance with a function of static
electricity removal has also become available.
To weigh the sample, it is advisable to use a glass
container with a diameter of 4 mm~5 mm.
When measuring, the container should be
inserted together with the sample directly into thereaction tube of the coulometer using tweezers.
5-2 Calibration
Calibrationofequipment

designed

specifically for solid sample is carried out using
Na2CO3.

For the calibration, Na2CO3 (purity

99.95 %) or high-purity inorganic material(CRM3005-a,purity99.970

±

0.016

%)

Fig. 2: Relationship between amount of CO2 andcoulometric titration value.

distributed by National Metrology Institute of Japan, AIST, Japan is used as the standard material forvolumetric analysis.

In addition, high-purity CaCO3 is sometimes used (Mörth and Backman, 2011).

For calibration of the instrument, 4 to 5 points of the standard in the range of 10 to 30 mg, and a further
5 to 10 points, including the acid blank, are measured.

For calibration, the slope is calculated by linear

regression of the amount of introduced CO2 calculated from the mass of the standard substance and the
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coulometric titration (counts).

This slope is used as a calibration factor (counts mol-1) for calculationof CaCO3 concentration.
If the instrument can process both solid and liquid samples, a Na2CO3 solution is used for calibration.
The solution is prepared according to Dickson et al. (2007).

The instrument is calibrated withmeasurements of 4 to 5 points in the standard solution and 5 to 6 points with the acid blank as describedabove.

As described above, the inear regression slope is obtained from the amount of CO2 and the

coulometric titration value (counts) (Fig. 2) and used as the calibration factor for the following
calculation of CaCO3 content:%CC =NS − b t − a 100.08

100
c
wsed

where,



%CC
NS
a
b
c

: CaCO3 content in sediment (%): Coulometric titration value (counts): Acid blank (counts)






t

: Measuring time (min)100.08

w sed: 100.08: Molar mass of CaCO3 (g mol-1): Mass of sediment sample used for analysis (g): Background count rate of the system (counts min-1): Calibration factor (counts mol-1)
5-3 Effect of terrestrial carbonateSeabed sediment contains CaCO3 (calcite) of terrestrial origin in addition to biogenic carbonates

such as coccolithophores and foraminifera.

Oba and Pedersen (1999) reported that CaCO3 derived

from atmospheric dust comprises up to 40 % of total CaCO3 in sediments of the coldest period of theLast Glacial Maximum in the Sea of Japan.

In addition, eolian dust from the Eurasian continent suchas kosa may contain dolomite (CaMg(CO3)2), depending on its source (Li et al., 2007).
Because dolomite has lower solubility in acid than calcite (e.g., Li et al., 2007), dissolution of
dolomite using acids such as 8.5 % phosphoric acid (Dickson et al., 2007) and 2 M HCl (Mörth andBackman, 2011), which are generally used in coulometric titration, takes a long time for the reaction tocompete.

Nevertheless, CaCO3 content in sediment measured by coulometric titration includes theinfluence of dolomite in addition to terrestrial calcite.

At present, unfortunately, there is no techniqueto clearly separate biogenic calcite from terrestrial calcite or dolomite.
6.

Organic matter
As a technique to estimate the organic carbon content in sediments, the loss on ignition method

combusting the sample at 550 °C has been used for a long time (e.g., Dean, 1974, Heiri et al., 2001).
However, the loss on ignition also contains the mass associated with dehydration and hydrolysis of clay
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minerals, and is therefore also affected by the clay content in sediments in addition to the conditions of
the analysis (Dean, 1974).

Therefore, in general, the amount of organic matter in the sediment isdetermined based on the organic carbon content in the sediment analyzed using an elemental analyzer.
In recent years, an elemental analyzer/isotope ratio mass spectrometer (EA/IRMS) has commonly been
used, and it is possible to measure nitrogen content and stable isotopic ratios of carbon and nitrogen in
addition to carbon content from the same sample.
The details of the measurement of organic carbon content using an elemental analyzer are describedin Volume 4 Chapter 1 of these guidelines (Yoshimura, 2016), and analysis using an EA/IRMS system
is described in Volume 4 Chapter 3 (Umezawa, 2016).

In this section, general points to be noted foranalysis of organic carbon/nitrogen contents and their stable isotope ratios in sediments using EA/IRMS
are described.
6-1 Samples and sample pretreatment
A required amount of dried sediment is transferred into a tin or silver sample capsule and precisely
weighed with a microbalance capable of measuring to 0.001 mg.

Because a sample with a large

amount of organic matter absorbs moisture during weighing, attention must be paid to controlling thehumidity and the temperature of the atmosphere in the laboratory. The balance should be installed in
an atmosphere with a relative humidity of 45 %~60 % and an air temperature of 20 °C~25 °C.
However, when the relative humidity becomes 45 % or less, caution is required; because the substanceon the balance will be charged, measurement error will be caused by the generated static electricity, andthe display of the balance will become unstable.

Recently, a balance with function of static electricity

removal has also become available.
Because impurities such as carbon are attached to the surfaces of tin or silver capsules in the
manufacturing process, there is a possibility that this carbon may affect the measurement of organiccarbon in samplse.

The sample capsules must be cleaned in advance of organic carbon analysis.

Inthis cleaning process, a 1:1 (v:v) mixture of methanol and dichloromethane is used (Ogawa et al., 2013).
In addition to cleaning with this methanol-dichloromethane solution, heating at 150 °C is effective fortin capsules (Maruoka, 2008) and heating for 3 hours at 550 °C is effective for silver capsules (Brodie
et al., 2011).

Five cleaned sample capsules are measured simultaneously with the samples, and theresult is regarded as a capsule blank for background correction.
To measure the organic carbon content and stable isotopic ratio, it is important to completely remove
the carbonate in the sample.

The dissolution and removal of this carbonate can be carried out by amethod of processing the sample using a silver sample capsule, or by processing the sample in acontainer such as a beaker or a centrifuge tube (Ogawa et al., 2013; Brodie et al., 2011; Schubert andNielsen, 2010).
When processing in a capsule, a silver sample capsule should be used.

The necessary amount of

sediment sample is weighed in the capsule, the sample is swollen with pure water, and the capsule is put
in a desiccator together with a beaker containing about 40 ml of concentrated HCl and left for about 24
hours to remove carbonate minerals.

During this process, care should be taken not to blow up the

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sample.

Also, as the pressure inside the desiccator rises with HCl vapor or generated CO2, it isnecessary to move the lid and release the pressure every few minutes initially and every few hours after
the reaction becomes stable.

Because carbonate sometimes does not dissolve completely (Schubert

and Nielsen, 2010), the sample capsule is taken out of the desiccator, 4 M HCl is added dropwise, andthe presence of reaction is checked.

When the reaction is insufficient, 4 M HCl can be dropped into

the sample until the reaction is not observed, and the sample can be heated on a hot plate at 50 °C as
necessary to reduce the solution and promote dissolution of the carbonate.
procedure is carried out in a fume hood.
on a well plate.

The above mentioned

In addition, it is easy to work by placing the sample capsules

When dissolution of the carbonate is confirmed, the sample capsules are heated on a

hot plate until the moisture and hydrochloric acid odor disappears.
an oven at 50 °C.

Thereafter, the capsule is heated at

Dried samples are kept in a desiccator until analysis.

sample capsules precipitates as hygroscopic CaCl2.

The calcium dissolved in

If the sample is stored in a desiccator over several

days, the sample should be dried in an oven at 50 °C immediately before it is wrapped in a tin capsule.
When processing the sample in a container such as a beaker or a centrifuge tube, attention should be
paid to avoid losing the sample particles.

It is recommended to use a centrifuge tube to reduce this loss

(Brodie et al., 2011). Two to three times the required amount of sample should be weighed for one
analysis in a 50 ml centrifuge tube, 5 ml of pure water is added dropwise to swell the sample, and 5 mlof 4 M HCl is gently added dropwise. Another 20 ml of 4 M HCl is added and the sample is left for
about 24 hours.

Then, 10 ml of pure water is added, and the sample is centrifuged for 10 min at 3000rpm (about 1500 g).

After the supernatant solution is removed with a pipette, 40 ml of pure water isadded to wash the sample after removal of carbonate, followed by centrifugation at 3000 rpm (about
1500 g) for 10 minutes. This washing operation is carried out twice.

Finally, after the supernatantsolution is reduced to 5 ml with a pipette, the sample in the centrifuge tube is frozen in a freezer anddried in a vacuum freeze dryer.

The dried samples are kept in the desiccator until analysis.

In theanalysis of the organic carbon and total nitrogen contents and the stable isotopic ratios of both elements,
the required amount of the carbonate-free sample is precisely weighed and transferred into a tin capsule.
As the organic carbon and total nitrogen contents measured by this operation are concentrations basedon the mass of the sample without sea salt and carbonate, they are converted into the concentrations perbulk sediment based on the water content and CaCO3 content.
6-2 Important point for analysis using an elemental analyzer/isotope ratio mass spectrometer(EA/IRMS)
In the elemental analyzer/isotope ratio mass spectrometer (EA/IRMS) system, gas is generated in
the elemental analyzer by combustion of a sample introduced through the reduction furnace, dehydration
column and gas chromatograph.
processes.

For this reason, isotopic fractionation occurs in each of theseBecause the value of the stable isotopic ratio measured by the EA/IRMS is relative to thestandard material, conditions such as the combustion temperature, the dilution ratio by He gas, and thetype of column of the gas chromatograph, as well as the correction method using the measured value ofreference materials affect the stability and precision of the measured value.

Therefore, it is necessary

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to carefully manage the obtained value at all times (e.g., Suzuki et al., 2012; Ogawa et al., 2013).
6-2-1 Preparation and introduction of samples
In the general EA/IRMS analysis, the necessary amount of the element for measurement is 30 μg for
C and 80 μg for N.

When the introduction amount to the mass spectrometer is decreased, sufficientsignal cannot be obtained and the influence of the blank increases.

Also, when the introduction amountincreases, fractionation caused by the introduction device becomes large (Ogawa et al., 2013).
Therefore, with reference to the measurable area of the equipment to be used, it is necessary to draw ascattergram showing the relationship between the isotopic ratio ( value, which may be a value for thereference gas) and the output (peak area) of m/z 44 in C and m/z 28 in N. In general, the N content inorganic matter is significantly lower than the C content, and the C/N ratio in sediments varies
spatiotemporally.

In EA/IRMS, when measuring C, the introduced CO2 is diluted by He before theappearance of the CO2 peak, and the relationship between the output and the measured value changes.
When preparing the scattergram, it is recommended to create one for each case of dilution and nodilution (Ogawa et al., 2013). From this scatter plot, the lower and upper limits of the output fromwhich a stable isotopic ratio (± 0.1 to 0.2 %) can be obtained are set, and the amount of sample to be
used for measurement is determined.

With regard to the measurement of N, the measured value mayvary due to the influence of N in the air, so it is necessary to ensure extrusion of the air when wrapping
the sample with the tin sample capsule.

A small amount of carbon contained in the tin/silver sample

capsule also influences the measurement as a blank.
6-2-2 Calibration and correction
If pretreatment and introduction of samples are properly performed, a positive correlation is foundbetween the output (peak area) and the introduced amount.
quantify the amount of C and N.

From this relationship, it is possible toIf combustion becomes incomplete or if separation of the peak

becomes insufficient because of accumulation of cinders in the combustion furnace and obstruction of
the combustion gas, the measured value vary and the correlation coefficient decreases (Umezawa, 2016:
Volume 4, Chapter 3). By monitoring the oxygen isotopic ratio measured in the CO2 measurementmode, it is possible to confirm the oxidation state and the presence of incomplete combustion (Sato andSuzuki, 2010).
When measuring with EA/IRMS, three or more types of work standards with different  values
should be measured for every ten samples. The working standards should be calibrated beforehandwith three to four internationally certified reference materials (Ogawa et al., 2013).

There is a liner

relationship between the  value of the working standard calibrated with the reference materials (ISM)
and the provisional  value of the working standard (RF:  value relative to the reference gas).
value of the sample is obtained from linear regression between the  values (RF = a ISM + b).

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The 

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6-2-3 Validation of the memory effect
In analysis by EA/IRMS, because samples are continuously introduced into a combustion furnacewith an auto sampler, depending on the properties and the isotopic ratios of the samples, the measured
result of a sample introduced later is influenced by the signals derived from the former samples.
is called the memory effect.
apparatus or the furnace.

This

The memory effect may change depending on the adjustment of theTo validate this effect, it is necessary to measure the working standards withdifferent isotopic ratios five times alternately (Sato and Suzuki, 2010).

For this measurement, it isdesirable for the sample amount for each analysis to be equalized as much as possible.

When anobvious memory effect is observed, the measurement result of a sample with a low  value immediately
after measuring a sample with a high  value is shifted toward the higher side than the value to be
indicated, and becomes gradually lighter from the second measurement. Generally, in the analysis ofstable isotopic ratios of C and N, this effect is small, but S isotopic ratio analysis often shows asignificant effect (Maruoka, 2008).

When a significant memory effect appears, it is necessary to make

improvements by adjusting the furnace and to take measures such as revision of measurement methods
or measuring samples multiple times (Sato and Suzuki, 2010).

References
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Imai, N. (2010): Investigation of the distribution of elements of the whole of Japan and their applications –Geochemical mapof land and sea of Japan–.

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Mortlock, R.A. and P.N. Froelich (1989): A simple method for the rapid determination of biogenic opal in pelagic
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Taylor, S.R. and S.M. McLennan (1985): The Continental Crust: Its Composition and Evolition. Blackwell Sci.
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Dymond, J., R. Collier, J. McManus, S. Honjo, and S. Manganini (1997) : Can the aliminum and titanium contentsof ocean sediments be used to determine the paleoproductivity of the oceans? Paleoceanography, 12, 586-593.
Hokanishi, N., A. Yasuda, and S. Nakada (2015): Major and trace element analysis of silicate rocks using fusedglass beads with an X-ray fluorescence Spectrometer. Bull. Earthq. Res. Inst. Univ. Tokyo, 90, 1-14.
Noriki, S., K. Nakanishi, T. Fukawa, M. Uematsu, T. Uchida, and S. Tsunogai (1980): Use of a sealed Teflon
vessel for the decomposition followed by the determination of chemical constituents of various marine samples.
Bull. Faculty Fish. Hokkaido Univ., 31, 354-361.
Yokoyama, T., A. Makishima, and E. Nakamura (1999) : Evolution of the coprecipitation of incompatible traceelements with fluride during silicate rock dissolution by acid digestion. Chem. Geol., 157, 175-187.
Komuro, C., H. Narita, K. Imai, Y. Nojiri and R.W. Jordan (2005) : Microplankton assemblages at Station KNOTin the subarctic western Pacific,1999-2000. Deep Sea Res. II, 52, 2206-2217.
Narita, H., M. Sato, S. Tsunogai, M. Murayama, M. Ikehara, T. Nakatsuka, M. Wakatsuchi, N. Harada and Y.
Ujiie (2002): Biogenic opal indicating less productive northwestern North Pacific during the glacial ages.
Geophys. Res. Lett., 29, 10.1029/2001GL014320.
DeMaster, D.J. (1981): The supply and accumulation of silica in the marine environment. Geochim. Cosmochim.
Acta, 45, 1715 – 1732.
Kamatani, A. and O. Oku (2000): Measuring biogenic silica in marine sediments. Mar. Chem., 68, 219-229.
Conley, D.J. (1998): An interlaboratory comparison for the measurement of biogenic silica in sediments. Mar.
Chem., 63, 39-48.
Lyle, A.O. and M.W. Lyle (2002): 6. Determination of biogenic opal in pelagic marine sediments: a simple method
revisited. In Proceedings of the Ocean Drilling Program, Initial Reports. Volume 199 (Lyle, M., Wilson, P.
A., Janecek, T. R., et al., eds), pp. 1-21. College Station, TX (Ocean Drilling Program).
Shimesh, A., R.A. Mortlock, R.J. Smith, and P.N. Froelich (1988): Determination of Ge/Si ratios in marine
siliceous microfossils: separation, cleaning and dissolution of diatoms and radiolaria. Mar. Chem., 25, 305323.
Nelson, D.M., P. Tréguer, M.A. Brzezinski, A. Leynaert, and B. Quéguiner (1995): Production and dissolution ofbiogenic silica in the ocean: revised global estimate, comparison with regional data and relationship to biogenic
sedimentation. Global Biogeochem., 9, 359-372.
Loassachan, N. and K. Tada (2008): Effect of solid to solution ratio on biogenic silica determination in coastal
sediments. J. Oceanogr., 64, 657-662.
Akiba F., Y. Tanimura, T. Oi, S. Ishihama, and R. Matsumoto (2014): Diatom biostratigraphy and diatom-derived
black grains of the uppermost Quanternary cores from the Japan Sea, and their paleoceanographic implications.
J. Jap. Assoc. Petroleum Technol., 79, 130-139.

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Michalopoulos, P. and R.C. Aller (2004): Early diagenesis of biogenic silica in the Amazon delta: Alteration,authigenic clay formation, and storage. Geochim. Cosmochim. Acta, 68, 1061-1085.
Müller, P. J. and R. Schneider (1993): An automated leaching method for the determination of opal in sediments
and particulate matter. Deep-Sea Res., 40, 425–444.
Dickson, A.G., C.L. Sabine, and J.R. Christian (2007): Guide to best practices for ocean CO2 measurements.
PICES Special Publication 3, https://www.nodc.noaa.gov/ocads/oceans/Handbook_2007.html
Mörth, C.-M. and J. Backman (2011): Practical steps for improved estimates of calcium carbonate concentrations
in deep sea sediments using coulometry.

Limnol. Oceanogr. Methods, 9, 565-570.

Oba, T. and T.F. Pedersen (1999): Paleoclimatic significance of eolian carbonates supplied to the Japan Sea during
the last glacial maximum. Paleoceanography, 14, 34-41.
Li, G., J. Chen, J. Yang, J. Ji, and L. Liu (2007): Dolomite as a tracer for the source regions of Asian dust. J.
Geophys. Res., 112, D17201, doi:10.1029/3007/JD008676.
Dean, W.E. (1974): Determination of carbonate and organic matter in calcareous sediments and sedimentary rocks
by loss on ignition: comparison with other methods. J. Sed. Petrol., 44, 242–248.
Heiri O., A.F. Lotter and G. Lemcke (2001): Loss on ignition as a method for estimating organic and carbonate
content in sediments: reproducibility and comparability of results. J. Paleolim., 25, 101–110.
Yoshimura, T. (2016): Particulate organic carbon (POC), particulate nitrogen (PN), and particulate phosphorus(PP). Guideline of Ocean Observations, Vo. 4, Chap. 1, G401EN:001-006.
Umezawa, Y. (2016): Carbon and Nitrogen Stable Isotopes in Particulate Organic Matter. Guideline of Ocean
Observations, Vo. 4, Chap. 3, G403EN:001-008.
Ogawa, N., G. Wang, H. Shinohara, and N. Ohkouchi (2013): Accurate measurements of carbon and nitrogenstable isotope ratio by EA/IRMS : technical guide for isotope ratio mass spectrometry.

Japan Chemical

Analysis Center.
Brodie, C. R., M.J. Leng, J.S.L. Casford, C.P. Kendrick, J.M. Lloyd, Z. Yongqiang, and M.I. Bird (2011): Evidence
for bias in C and N concentrations and 13C composition of terrestrial and aquatic organic materials due to preanalysis acid preparation methods. Chem. Geol., 282, 67-83.
Maruoka, T. (2008): Isotope analysis of carbon and sulfur in solid materials using continuous-flow isotope ratio
mass spectrometer: Improvements for high-precision analysis. Chikyukagaku (Geochemistry), 42，201-216.
Schubert, C.J. and B. Nielsen (2010): Effects of decarbonation treatments on 13C values in marine sediments.
Mari. Chem., 72, 55-59.
Suzuki , Y., Y. Chikaraishi, K. Yamada, and N. Yoshida (2012): Interlaboratory comparison of carbon, nitrogen,and oxygen isotope ratios in organic chemicals using elemental analyzer-isotope ratio mass spectrometer.
Bunseki Kagaku (Analytical Chemistry), 61, 805-810.
Sato, R., and Y. Suzuki (2010): Carbon and Nitrogen stable isotope analysis by EA/IRMS. Res. Org. Geochem.,
26, 21-29.

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Pore water‫ۑ‬Hisashi NARITA (Tokai University), Shigeyoshi OTOSAKA (Japan Atomic Energy Agency)

Physical, chemical and biological changes that occur during sedimentation and consolidation in theseafloor are collectively termed “diagenesis”. In particular, oxidative decomposition of organic matteroccurring several meters beneath the seafloor, and various changes in chemical composition and thosedue to mineral formation are termed early diagenesis.

Changes in the concentration of chemicalcomponents due to changes in the sedimentary environments are more pronounced than those due todiagenesis. For this reason, it is extremely difficult to measure diagenesis directly from changes in thechemical composition of sediments, except that of the uppermost surface layer of the sediment. To
clarify our understanding of diagenesis, including early diagenesis, measurement of the chemicalcomponents of pore water is extremely effective (e.g., Masuzawa and Kitano, 1983; Gamo and Gieskes,
1992).

In particular, it is crucial to measure chemical constituents of pore water to determine themigration velosity of substances in the sediment-seawater boundary layer accompanying changes in theredox environment of the sediments (e.g., Berner, 1980; Watanabe and Tsunogai, 1984; Anderson et al.,1989). Moreover, by measuring the stable isotopic ratio of oxygen and hydrogen in pore water and thechloride ion concentration, including a correction of the effect of advection/diffusion, it is possible toreconstruct past salinity fluctuations above the seafloor (Kato et al., 1996a; Adkins et al., 2002; Schraget al., 2002). Also, using chloride ions and oxygen and hydrogen isotopes, it is possible to infer the
existence of the advection of pore water (Kato et al., 1996a), and to estimate the diffusion velocity (e.g.,
Spivack et al., 2002; Toki et al., 2014).
1.

Sediment samplingCore samplers such as multiple, gravity and piston corers are used for sediment coring for collecting

pore water.

Details of sediment sampling are described in Chap. 5 of this volume. In particular, forresearch aimed at estimating the migration rate of substances in the sediment-seawater boundary layer,
the use of a multiple corer that can collect the overlying water is recommended. For studies in coastal
areas and lakes that require a sediment cores several meters in length or longer, mechanical rotary boring
using a hydraulic thin-wall sampler may also be used in sampling.2.

Sampling of pore water
As a method for separating pore water from sediments, the centrifuge method and pressurization

method are commonly used.

The sediment core is sliced into thin layer immediately following

collection, and the subsample is placed in a centrifuge tube or a polyethylene syringe for pore water
separation. Manheim (1968) and Kato et al. (1996b) are good examples of studies using a polyethylene
syringe.

When a large amount of pore water is required or pore water must be separated from sedimentwith low water content, a stainless pressurized container combined with a hydraulic pump can also be
used to squeeze pore water (Manheim and Sayles, 1974; Gamo and Gisekousu, 1992).

Otherwise, in-situ sampling of pore water using a special suction unit has also been proposed (Sayles et al., 1976;
Masuzawa et al., 1991; Beck et al., 2007).
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Pore water separated from sediment is filtered through a ȝP RUȝP GLVSRVDEOHPHPEUDQH
filter and analyzed as quickly as possible.

The material of the filter must be tested and selected

carefully to reduce the effect of contamination of the target component.
mixed ester filter potentially causes contamination of NO2.

For example, a cellulose-

If the sample can not be analyzed

immediately and must be stored until analysis, the pore water should be placed in a polyethylene or glass
container, depending on the target component; sealed without creating headspace; and stored in arefrigerator.

In the case of heavy metal measurement, nitric acid should be added and the sample

should be sotred in an acidic condition of approximately pH 2. In the case of the measurement ofcomponents that may change due to microbial activity, mercuric chloride is added prior to storage. In
these cases, it is necessary to accurately obtain the dilution rate of the pore water by adding chemicals.
In the case of the analysis of alkali and alkaline earth metals, sulfides, sulfate ions, halogen etc., it is notnecessary to acidfy the sample. When storing a pore water sample, it is necessary to minimize theevaporation of water.
3.

Effects to consider during pore water sampling
Gases in contact with pore water during collection of sediment and separation of pore water may

have a significant effect on the concentration of chemical constituents in the separated pore water (e.g.,
Masuzawa et al., 1980; Toole et al., 1984; Barnes and Cochran, 1988). In particular, to remove theeffects of pressure, temperature, and oxygen at the time of separation, the only means is to separate thepore water in the sediments at the site. To solve this problem, an in-situ pore water sampler that canbe used in the deep sea has been developed (Sayles et al., 1976; Masuzawa et al., 1991) and an in-situ
sampling method for shallow water (Seeberg-Elverfeldt et al., 2005; Beck et al., 2007) has also beendeveloped.

If pressure change is excluded, during pore water separation temperature andcontamination by oxygen in the atmosphere are important.
3-1 Pressure effect

The difference in pressure between the site where the sediment was collected and that where thepore water is separated influences the concentration of the chemical components in the pore water to aconsiderable extent. To eliminate this effect, there is no means to separate the pore water at the site.
As an example of the influence of pressure change, an increase in uranium concentration in pore water
due to dissolution of carbonate has been reported (Toole et al., 1984). It is also known that dissolved
gases with low solubility, such as methane, are degassed as pressure decreases from sampling toseparation (Jørgensen and Kasten, 2006).
3-2 Temperature effect

In many cases, the temperature of the sediment increases during the sampling process from sedimentcollection to pore water separation. Therefore, sediment samples should remain refrigerated except
when the samples are being sliced or packed. If possible, these processes should be performed in a
low-temperature laboratory, and when separating the pore water, it is necessary to use a temperatureGuideline of ocean observations Vol. 5 Chap. 6 Pore water © Hisashi NARITA, Shigeyoshi OTOSAKA 2018 G506EN:001-006

G506EN-3

controlled centrifuge or a low-temperature thermostatic tank so that the samples can be remain in asimilar environment as that of the sampling site. Temperature control during pore water separation isparicularly crucial in measurements of chemical components such as potassium, silicon, boron,
magnesium and total alkalinity in pore water, of which the reversible dissolution equilibrium between
the solid-liquid phase dominates the concentration in the pore water. To eliminate the influence oftemperature from the measurement of these components in pore water, the sediment is sealed in acontainer such as a syringe, adjusting the temperature to that of the sampling site. After reaching theset temperature, it is maintained for 3 to 4 hours, and then pore water separation is initiared (Masuzawa
et al., 1980).
3-3 Effect of contaminants in the atmosphere

Except for pelagic sediments such as red clay, becasue dissolved oxygen in pore water in sediments
is consumed by decomposition of sedimentary organic matter, the concentration is lower than that in thebottom water on the seabed or is zero. Therefore, when separating pore water, it is necessary to avoid
sediments contact with the atmosphere, which contains a high concentration of oxygen, following
collection.

For this purpose, the processes of removing the overlying water of the sediment core,slicing the sediment, and packing the sliced samples in containers must be performed rapidly or under anitrogen atmosphere.

It should be noted that the influence of the concentrations of the target

components cannot be sufficiently eliminated for uranium in the pore water of reductive coastal
sediments even if such operations are performed (Barnes and Cochran, 1988; Nagao et al., 1992).
As a method of separating the pore water without allowing sediment to come into contact with theatmosphere, a piston is mounted above and below the core tube and the pore water is separated while
being pressurized (Bender et al., 1988; Jahnke, 1988). Fig. 1 shows a schematic diagram of a methodof compressing and separating pore water by Jahnke (1988).

Nagao et al. (1992) succeeded inmeasuring uranium in pore water using this method without the influence of contamination.

However,under method it is difficult to control the temperature, unless separation work of pore water is performed
in a low-temperature laboratory.

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G506EN-4

Fig. 1: (a) Overview of the squeeze
separation method of pore waterand that of the (b) syringe barrel(Jahnke, 1988). Before sedimentcoring, drill 4.2 mm holes at theside wall of the core barrel with aninterval of 2~5 cm, and cut a screw
thread (M5) in the holes. Keep theM5 screws in the unused holes.
Turn the handle and push up thelower piston to squeeze the porewater. Modfied from Narita andKato (2007).

In recent years, a method of collecting pore water using a Rhizon sampler has been applied as well
to seabed sediments (Seeberg-Elverfeldt et al., 2005; Dickens et al., 2007). The Rhizon sampler wasdeveloped as an artificial plant root during the 1990s for the purpose of collecting soil water in the fieldof soil science. This sampler is a capillary composed of a hydrophilic porous polyether sulfone (PES),
which has (1) a capillary of a hydrophilic porous polymer (diameter of 2.5 mm, average pore diameter
RIȝP   DZLUHVXSSRUWLQJWKHFDSLOODU\  DWXEHRISRO\YLQ\OFhloride (PVC)/polyethylene(PE) that allows water to pass through the capillary, and (4) a luer connector. When collecting porewater using a Rhizon sampler, insert the Rhizon sampler into the sediment from a small hole at the sideof a core barrel, connect the polyethylene syringe or peristaltic tube to the luer connector, and aspirate
to collect the pore water. Otherwise, connect the injection needle to the luer connector and collect thepore water vis a collection tube which is evacuated. This method can separate the pore water without
sediment contact with the atmosphere and without destroying the sediment. It is also possible to collectpore water at sampling intervals of 1 cm (Seeberg-Elverfeldt et al., 2005).

However, because the porewater is collected by suction, it is unsuitable for measurement of dissolved gas components such as
dissolved inorganic carbon, total alkalinity and pH (Schrum et al., 2012). It has also been noted that,in measuring oxygen and hydrogen isotopic ratios and chloride ion concentration, a systematicdifference exists between the measurement results using this method and those of the conventionalsqueezing method (Miller et al., 2014).

In the sampling of pore water using a Rhizon sampler, it may

take several tens of minutes to 1 hour for completion suction of the pore water. In the meantime, it isnecessary to control the temperature during aspiration by storing the sediment column in a large-sizedrefrigerator or a low-temperature laboratory. Because it is almost impossible to aspirate the pore waterfrom the deep layers of sediment with a low water content, it is necessary to use the squeezing method
together with the Rhizon sampler.
Guideline of ocean observations Vol. 5 Chap. 6 Pore water © Hisashi NARITA, Shigeyoshi OTOSAKA 2018 G506EN:001-006

G506EN-5

4.

Summary
In this chapter, cautions regarding the sampling of pore water are described. Each method has

advantages and disadvantages, and it is no exaggeration to say that there is no common method toseparate pore water that is applicable for all chemical components.

When collecting pore water, it isnecessary to select an appropriate sampling method according to the target component, or to change themethod of processing the subsample for each component (Schrum et al., 2012). Among the effects ofpressure, temperature, and gaseous contaminant, temperature may irreversibly change the concentrationof components related to the dissolution equilibrium between sediment and pore water, as well as
microbial activity in the sediment, concentrations of organic components, and trace gasses (Ijiki et al.,2013). Therefore, it is necessary to process the samples quickly from sediment sampling to pore water
separation, to minimize the temperature change as much as possible, and to separate the pore water at atemperature near that of the sampling site. Furthermore, it is recommended that separation of porewater be performed after the temperature of the sample reaches that of the sampling site (Masuzawa etal., 1980). Depending on the target components, elution of contaminants from the filter or adsorptionof the target components to the filter may occur; thus, it is necessary to conduct blank tests and cleaningof the filter in advance.
References
Masuzawa, T and Y. Kitano (1983) : Interstitial water chemistry in deep-sea sediments from the Japan Sea. J.
Oceanogr. Soc. Japan, 39, 171-184.
Gamo, T., J.M. Gieskes (1992):

Shipboard chemical analyses of sedimentary pore waters during the Ocean

Drilling Program (ODP) Leg 131. Chikyukagaku, 26, 1-15. (in Japanese)
Berner, R.A (1980) : Early diagenesis: A theoretical approach.

Princeton Univ. Press., Princeton, NY. 256 pp.

Watanabe, Y. and S. Tsunogai (1984) : Adsorption-desorption control of phoshate in anoxic sediment of acoastal sea, Funka bay, Japan. Mar. Chem., 15, 71-83.
Anderson, R.F., A.P. Lehuray, M.Q. Fleisher, and J.W. Murray (1989) : Uranium deposition in saanich inlet
sediments, vancouver island. Geochim. Cosmchimi. Acta, 53, 2205-2213.
Kato, Y., T. Miyata, H. Wada, H. Minami (1996a): Diffusion of chloride in sediments of a brackish lake:
distributions of chlorinity in pore waters of drillcores from Lake Hamana. Umi no kenkyu (Oceangr. Japan.),
5, 97-106. (in Japanese)
Adkins, J.F., K. Mcintyre, and D.P. Schrag (2002): The salinity, temperature, and G18O of the glacial deep ocean.
Science, 298, 1769-1772.
Schrag, D.P., J.F. Adkins, K. McInerine, J.L. Alexander, D.A. Hodell, C.D. Charles, and J.F. McManus (2002) :The oxygen isotopic composition of seawater during the last glacial maximum. Quat. Sci. Res., 21, 331-342.
Toki, T., U. Tsunogai, T. Gamo, S. Kuramoto, and J. Ashi (2004): Detection of low-chloride fluids beneath acold seep field on the Nankai accretionary wedge off Kumano, south of Japan. Earth Planet. Sci. Lett., 228,
37-47.
Manheim, F.T. (1968): Disposable syringe techniques for obtaining small quantities of pore water fromunconsoidated sediments. Journal of sedimentary Research, 38 (2), 666-668.
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G506EN-6

Kato, Y., H. Minami, S. Okabe, H. Wada, H. Kitazato (1996b):
anoxic sediments from Lake Hamana.

Remineralization of biophile elements in

Umi no kenkyu (Oceangr. Japan.), 5, 221-234. (in Japanese)

Manheim, F.T. and F.L. Sayles (1974): Composition and origin of interstitial waters of marine sediments, basedon deep sea drill cores. In: The Sea, Vol 5 (E.D. Golderg ed.), 527-568.
Sayles, F.L., P.C. Mangelsdorf, T.R.S. Wilson, and D.N. Hume (1976) : A sampler for the in situ collection ofmarine sedimentary pore waters. Deep Sea Res., 23, 259-264.
Masuzawa, T., Y. Kato, S. Nakashima and S. Nagao (1991) : An in-situ pore water squeezer for obtaining porewaters at multi-depths in marine sediments. In: Proc. 3rd Intl. Symp. on Advanced Nuclear Energy Research:Global Environment and Nuclear Energy, JAERI, Tokai, 258- 261.
Beck, M., O. Dellwig, K. Kolditz, H. Freund, G. Liebezeit, B. Schnetger, and H.-J. Brumsack (2007) : In situ
pore water sampling in deep interidal flat sediments. Limnol. Oceanogr. Methods, 5, 136–144.
Toole, J., J. Thomson, T.R.S. Wilson and Baxter, M.S. (1984): A sampling artifact affecting the uranium content
of deep-sea porewaters obtained from cores. Nature, 308, 263-266.
Masuzawa, T., S. Kanamori and K. Kitano (1980) : The reversible effect of temperature on the chemicalcomposition of interstitial water of marine sediment. J. Oceanogr. Soc. Japan, 36, 68-72.
Seeberg-Elverfeldt, J., M. Schlüter, T. Feseker, and M. Kölling (2005), Rhizon sampling of porewaters near the
sediment-water interface of aquatic systems. Limnol. Oceanogr. Methods, 3, 361–371.
Jørgensen, B.B. and S. Kasten (2006): Sulfur cycling and methane oxidation. In: Schulz, H.H., Zabel, M. (Eds.),
Marine Geochemistry, second ed. Springer, Berlin, pp. 271–309.
Barnes, C.E. and J.K. Cochran (1988): The geochemistry of uranium in marine sediments. In: Guary, J.C.,
Guegueniat, P., Pentreath, R.J. (Eds.), Radionucleides: A Tool for Oceanography. Elsevier, London, 162–
170.
Nagao, S., H. Narita, S. Tsunogai, K. Harada and T. Ishii (1992): The geochemistry of pore water uranium incoastal marine sediments from Funka Bay, Japan. Geochem. J., 26, 63–72.
Narita, H. and Y. Kato (2007): “2.2.5 Sediment and pore water”, ed. The Chemical Society of Japan, The Fifth
Series of Experimental Chemistry, Vol. 20-2 Enviromental Chemistry, Maruzen Press., Tokyo, p. 105-110.
Bender, M., W. Martin, J. Hess, F. Sayles, L. Ball and C. Lambert (1987): A whole-core squeezer dor interfacial
pore-water sampling. Limnol. Oceanogr., 32, 1214-1225 .
Jahnke, R.A. (1988): A Simple, reliable, and inexpensive pore-water sampler. Limnol. Oceanogr., 33, 483-487.
Dickens, G. R., M. Kölling, D. C. Smith, and L. Schnieders (2007): Rhizon sampling of pore waters on scientificdrilling expeditions: An example from the IODP Expedition 302, Arctic Coring Expedition (ACEX), Sci.
Drill., 4, 22–25.
Schrum, H.N., R.W. Murray, and B. Gribsholt (2012) : Comparison of Rhizon sampling and whole roundsqueezing for marine sediment porewater. Sci. Drill., 13, 47–50.

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Plankton Net‫ۑ‬Hiroaki SAITO (Atmosphere and Ocean Research Institute, The University of Tokyo)

1.

Plankton net
Plankton are drifting organisms in water bodies because they are nonmotile or poor ability to swim

against a current. Most of them are tiny <20 mm, but some gelatinous plankton such as jellyfish andtunicates are larger than 100 mm with weak swimming ability. In marine ecosystems, the density ishigher for smaller organisms. For small plankton (~0.2 mm), such as bacteria, archaea, phytoplankton,
protozoan zooplankton, collecting water samples (milliliters to liters) and concentrating them withvarious methods (Vol. 4). In order to collect larger metazoan zooplankton which density is much lower,
we need to concentrate organisms from much larger volume of water than water bottle sampling.
Plankton nets are sampling devices of plankton that are towed thorough water and filter plankton larger
than the mesh size. Fig 1 shows a NORPAC (North Pacific Standard) net and a WP-2 (UNESCO
Working Party 2) net, which are widely used conical net and cylinder-conical net, respectively.
The minimum size of plankton collected with a plankton net is defined by the mesh size. The
maximum size is influenced by variable factors such as tow speed and mouth opening size of theplankton net, swimming speed and visual or mechanosensory recognition ability of plankton. For the
sampling of micronekton, which swim faster than zooplankton, larger nets or trawls allowing high speed
tow are used (e.g., IKMTࠊMOHTࠊRMT, Sameoto et al., 2000; Oozeki et al., 2004). Plankton nets
are also used for micro phytoplankton and microzooplankton sampling such as diatoms, radiolarians,
forminiferans. In this manuscript, we use a term “zooplankton” as metazoan zooplankton which are themain target of plankton net sampling.
2.

Filtering efficiency of plankton net and filtering rate
The choice of the type of plankton net, mesh size and towing method are depending on target

zooplankton species and groups. A plankton net with larger mouth area filters more water in a certain
amount of time and reduces the possibility of net avoidance of zooplankton. On the other hand, requiring
larger filtering area (i.e., net length) to minimize the influence of net clogging by phytoplankton anddetritus and to sustain the filtering efficiency during tow. The initial filtering efficiency (IFE) of aconical net is 75-85%, and one of conical-cylinder net, such as WP-2 (Fig. 1), reaches around 100%
(Keen, 2013). IFE is decreasing with net tow due to net clogging. The decline in the filtering efficiency
is more serious in the water with high abundance of chain-forming diatoms and/or sticky organisms
such as Noctiluca. These organisms are usually abundant in the surface layer of the water column. Thus,
the declining of the filtering efficiency means not only decreasing the filtering volume but also inducing
the underestimation of the zooplankton abundance distributing in the surface layer and crucial impact
on the quantitative sampling.

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The Open Area Ratio (R) is the ratio of the filtering mesh area to the mouth area of net.
R = aE/ A
Where, a, E, A mean mesh area, mesh porosity, and mouth area, respectively.
E= m2 / (d + m)2
m means mesh width, and d the diameter of mesh filament. Since the filtering efficiency declines
with filtering volume by net clogging, a plankton net with large R is appropriate using in plankton richwaters. The minimum R for quantitative sampling is represented as follows (Sameoto et al, 2000),
Green water

Log 10 (R) = 0.38 x Log 10 (V / A) - 0.17

Blue water

Log 10 (R) = 0.37 x Log 10 (V / A) - 0.49

where V means the filtering volume of sea water (m3). In the case of 150-m vertical tow of a
NORPAC net (Fig. 1) fitted with 335 Pm Nytal mesh (R=3.7), the net clogging is estimated to be notserious in blue water (minimum R=2.1). But in green water, the filtering efficiency may decline(minimum R = 4.5). Tranter and Smith (1968) recommended R>5 for a plankton net fitted withmesh>0.33 mm, and R>9 for mesh<0.33 mm (Keen, 2013). In Japan, short conical nets have been usedbecause of easy-handling on small ship and also low product price. The users should be careful these
low R nets are easy clogging and inappropriate for quantitative sampling in green water.
In order to determine the filtering volume of sea water during net tow, a flow meter is mounted at
net mouth as confronted with towing direction. For a plankton net with bridles in front of the net, theflow meter should be set deviated from the mouth center to minimize the interfere of bridles on the flow
field (e.g., in quarter of the diameter). The flow meters should be calibrated at calm sea surface condition.
Using the plankton net frame without net or a calibration frame, towing more than 7 times to obtain therevolution of the flow meter in a certain distance towed at 100 % filtering efficiency. The revolution per
distance can be changed by strong impact such as hitting to the hull or falling on the deck. The flow
meter should be rinsed with fresh water to remove salt after use.
3.

Plankton net sampling and sample handling
It has been developed various plankton nets to collect zooplankton (Wiebe and Benfield, 2003).

The towing methods of plankton nets which widely used in Japan are summarized in Hasumoto (2006).
Towing methods are categorized as: 1) vertical tow, 2) oblique tow, 3) multi-layer sampling with
opening-closing nets, 4) neuston sampling. In this manuscript,

describing the sampling procedure withvertical tow and sample handling at first, then other towing methods and devices.
3-1 Vertical tow

Vertical tow of a plankton net is widely used sampling method which enable to estimate zooplankton
abundance and biomass per area in relatively short sampling time. This method has been widely usedfor various monitoring projects. Because of relatively low filtering volume, it is inadequate for
examining the abundance for minor species.
In the case of using a NORPAC net, a 10-30 kg lead weight is used as a sinker. To avoid twistingbridles and/or rope, use swivel to connect with wire and the weight (Fig. 1). When the net is at the sea
surface, make zero-correction of the wire length meter. To prevent the generation of kink of wire, theGuideline of ocean observations Vol. 6 Chap. 1 © Hiroaki SAITO 2016 G601EN:001-009

G601EN-3

pay out speed of the wire is to be adjusted to keep the wire tension, especially when the net is at the sea
surface. In the calm sea condition, the pay out speed may reach 1 m s-1.
When the wire length is approaching to the target depth, measure the wire angle and pay extra length(Table 1) out to reach the net to the target depth. Hauling speed is generally 0.5-1.0 m s-1. It has been
observed that zooplankton specimens are taken in poorer condition at higher towing speed. Also,
inducing escapement through the mesh due to the high filtration pressure. The decline of the filtering
efficiency at high speed towing is more serious for conical net than cylinder-conical net. At the sea
surface, it should be careful that the plankton net can be damaged by wind and swell under the roughsea surface condition.
Since some plankton are caught in mesh or stick on due to the mucus, wash the plankton net carefullyusing an appropriate flow of sea water from the outside of the net to remove plankton. Clogging near
the cod end is usually more serious. The cod end is taken off and the obtained samples are transferred
into a sampling bottle or jar (see 4). Record the revolution and ID of the flow meter.
In order to collect live zooplankton for experimental studies or obtain less damaged specimen, it isrecommended to tow slowly (<50 cm s-1) and use a large cod end. It has been used several to tens literof bottle or plastic bag (Fig. 2) for the cod end. It is effective to enlarge the bottom diameter of theplankton net to allow smooth transfer of zooplankton to the cod end. The sample is transferred without
net washing to minimize the mixing of damaged plankton stuck on the mesh.
Obtained samples are appropriately processed depending on the purpose. For species enumerationand identification, fix with sodium borate (Na 2 B 4 O 7 ࣭ 10H 2 O) buffered formalin-seawater (final
concentration of formaldehyde is 4 %) as soon as possible. It is recommended fixing the sample with
8 % fromaldehyde in the case that plankton volume is more than 30% of the sample bottle. Ethylalcohol
is used for DNA sequence. Since RNA is labiler than DNA, a zooplankton sample for RNA is kept
frozen or with specific chemicals for the preservation. It is recommended to refer latest literatures for
RNA preservation. For the measurement of dry weight or carbon and nitrogen weight, filter on
precombusted (450oC, 4 hour) glass fiber filter such as Whatman GF/A after dividing the sample using
sub-sampling devices such as Folsom’s splitter as necessary. Sub-sampling devices is to be set on abench appropriately to avoid errors through the splitting process. Since some commercial products are
not enough stable, determine the variability between splits at land-based laboratory before use. For dry
weight measurement, rinse the filter with a small amount of distilled water to remove the salt (Ohmori,1978). The filter is transferred to petri dish and kept in freezer until measurement. Or, the filter is folded
in half, covered with combusted aluminum foil and kept in freezer. The sequential processes of freezing
and thawing is required, such as for gut pigment analysis, using mesh for plankton net as a filter inducing
less damage than glass fiber filter. For gut pigment analysis, the sample on the mesh is kept in freezer<-70oC to prevent the degradation of pigments. For any purposes, fix or freeze the sample as soon as
possible. Even for the fixation with formalin, leaving a sample more than 30 minutes in room
temperature induces significant damage.
The following are potential troubles and mistakes at a plankton net towing and sample handling: 1)
wire breakage due to the generation of kink, 2) net breakage by wind and swell, 3) sample loss due tothe cod end breakage or fall out of clip, 4) sample loss during transferring sample from cod end, 5)
Guideline of ocean observations Vol. 6 Chap. 1 © Hiroaki SAITO 2016 G601EN:001-009

G601EN-4

undescribed or insufficient description of sampling information. We have to be very careful to avoid thecase 1) which can induce serious accident. The second case is more probable on clogged net withcontaining sea water at the recovery. During handling the sample, it should be careful for unexpectedrolling and running sea water on deck. To avoid case 5), take care that sampling bottle is properly marked
at both lid and bottle. In the case of formalin fixation, input a waterproof paper with describing theinformation.
3-2 Oblique tow

For an oblique tow, various nets such as WP-2 net, Bongo-net (Fig. 3), ORI net (Fig. 4) have beenused. The larger filtering volume than obtained with a vertical tow allows more accurate estimation of
the composition of zooplankton population and abundance. Also, reducing the influence of plankton
patchiness.
To enhancing the downforce, attaching a depressor or weight (30-100 kg) with a swivel. Setting asmall depth sensor or acoustic net monitor at the flame to record the towing depth. Steaming the ship at
low speed and put down the net to the sea surface, and then pay the wire off and control the ship speed(1.0-2.5 knot) to make the wire angle 45o. When the net is estimated to reach the target depth from thenet sensor or wire length and angle, record the wire length and time, and haul the wire at stable speed(0.2-1.0 m s-1). The net towing speed, i.e., wire speed + ship speed, should be controlled to keep thefiltering efficiency high enough. Obtained samples are processed as one of vertical tow.
3-3 Multi layer sampling

In order to collect zooplankton samples from multi-layers in a single tow, plankton nets with an
opening-closing system controlled by logging the depth through armored cable with conductor, such as
MOCNESS, VMPS, are used. A plankton net with closing system controlled by falling messengers,
such as MTD net, had used in the past. However, such a net is hard to detect the exact sampling layer,difficult to exclude the possibility of contamination at paying out the wire, and unstable performance ofthe closing system. The contamination from outside the target depth induces serious error to examine
the vertical distribution of species and developmental stages.
There are various types in MOCENESS, VMPS and another multi-layer sampling gears, and mostof them equip various sensors for environmental parameters such as temperature, salinity, phytoplankton
fluorescence, etc. In general, the 1st net which is set open during downcasting is not useful for
quantitative sampling.
3-4 Neuston sampling

Neuston nets are designed to collect zooplankton, fish eggs and larvae occurring very surface of thewater column. A Chigyo-net (Maruchi-net) has been widely used in Japan. A Chigyo-net is towed besidethe ship being the upper 1/3 of the ring above the sea surface by controlling wire length. Since it isunable to estimate exactly the filtering volume, only the biomass and abundance per towing time or
distance are obtained. To eliminate the influence of ship light, shut the light down at nighttime tow.

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G601EN-5

ORI-nueston is towed by a bridle attached to one side of the net frame (Fig. 5). This makes freeopen area without wire and bridle during the net tow, keeping the net far away from the ship relative to
Chigyo-net and minimize the influence of bow wave. Neuston nets stacking multiple nets vertically can
examine the fine vertical distribution of zooplankton within the neuston layer (Wiebe and Benfield,2003).
4.

CodendZooplankton collected by towing a plankton net are concentrated into a cod end attached at thebottom of the net. The materials of cod end and handling procedure are variable: 1) Cod end with rubber
tube at the bottom. Folding the tube and pinched with a clip at sampling. Drain sea water and plankton
off by removing the clip, 2) Cod end with screw cap. The cod end is screwed in the bottom of the net.
After sampling, screw off the cod end to transfer samples, 3) Canvas or mesh bag. Attach and detachfrom the net with a hose clamp or strings. The cod end with screw cap is made by plastic or vinyl
chloride, opening windows at the side covered by mesh to drain sea water. The mesh opening at the side
windows is to be the same or smaller than one of the plankton net. Since strong filtering pressure exert
on the windows, check the damage and rinse fully to remove clogging after sampling.
5.

MaintenanceNet clogging should be carefully washed off to maintain the filtering efficiency of the net andcontamination. Nets should always be checked to be sure without damazed gauze, loozend screws andropes. Wash metal materials with fresh water to remove salt. It should be noted that metal is more
susceptible to corrosion at high temperature-high humid condition. After the cruise, remove all the parts
and kept in fresh water for a day to remove salt. Then dry and keep in bags.
References
Hasumoto, H. (ed) (2006) Kaiyo-Kansoku Manual. ORI, the University of Tokyo, 258 pp. (in Japanese)
Keen ,E. (2013) A practical designer’s guide to mesozooplankton nets. 1-52. http://acse
http://acsweb.ucsd.edu/~ekeen/resources/Choosing-a-Net.pdf
Ohmori, M. (1978) Some factors affecting on dry weight, organic weight and concentrations of carbon andnitrogen in freshly prepared and in preserved zooplankton. International Review of Hydrobiology, 63, 261269.
Oozeki, Y., Hu, F, Kubota, H., Sugisaki, H., Kimura, R. 2004. Newly designed quantitative frame trawl forsampling larval and juvenile pelagic fish. Fisheries Science 70, 223-232.
Sameoto, D., Wiebe, P, Runge, J., Poste, L., Dunn, J., Miller, C, Coombs, S. 2000. Collecting Zooplankton. In:
Harris et al. Ed., ICES Zooplankton Methodology Manual, Elsevier Academic Press, London, pp55-81.
Tranter, D. J., Smith, P. E. (1968) Filtering performance. In: Tranter, D. J. (ed) Monographs on oceanographic
methodology 2, Zooplankton sampling”, UNESCO Press, Paris, 27-56 pp.
Wiebe, P.C, Benfield, M. H. (2003) From the Hensen net toward four-dimensional biological oceanography.
Progress in Oceanography 56, 7-136.

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G601EN-6

Fig. 6-1 NORPAC(North Pacific Standard) net and WP-2 (UNESCO Working Party No.2) net.

Guideline of ocean observations Vol. 6 Chap. 1 © Hiroaki SAITO 2016 G601EN:001-009

G601EN-7

Fig. 2. A plankton net attached large plastic bag as a cod end to collect living zooplankton for incubation
experiment.

Fig. 3 BONGO net (70 cm ring diameter).

Photo by Dr. Y. Okazaki.

Guideline of ocean observations Vol. 6 Chap. 1 © Hiroaki SAITO 2016 G601EN:001-009

G601EN-8

Fig. 4 ORI net (1.6 m ring diameter).

Fig. 5 Neuston net

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G601EN-9

Table 1. Correction depth estimated from wire angle. Depth means the target depth of a plankton net.

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Benthos‫ۑ‬Shigeaki KOJIMA (Graduate School of Frontier Sciences / Atmosphere and Ocean Research Institute, The
University of Tokyo)

1. Size categories of benthos
Benthic organisms (benthos) are organisms living on/in bottom sediments. Demersal fishes which
spend most time setting on the sea bottom such as soles and eelpouts, or swimming above the bottom tofeed as rattails are mostly classified into them. Benthos is conveniently divided into some size
categories based on differences in sampling and observing methods. Megabenthos is a category which
includes organisms large enough to be visible with the naked eye and sampled by using dragnets suchas beam trawls and dredges. Organisms of smaller categories are generally sampled with bottom
sediment by using bottom samplers. Among them, organisms remained on a mesh of 0.5 mm or 1 mm
openings are called as macrobenthos. Organisms which pass through a mesh of 0.5 mm or 1 mm
openings and remained on a mesh of 38 ȝPRSHQLQJVDQGWKRVHZKLFKSDVVWKURXJKDPHVKRI8 ȝP
openings are meiobenthos and microbenthos, respectively.
2. Sampling and observing methods of megabenthos
Megabenthos has been collected by dragnets such as beam trawls and dredges for a long time.
Biological dredges we use have same structures as those used during the research cruise in the Aegean
Sea by Edward Forbes in 1840s, which is famous as the first systematic survey of deep-sea organisms.
Biological dredges are used at sand and mud bottom at relatively shallow sites. Unlike dredges forgeological studies, they collect organisms into light-weight nylon nets. Dredges of various sizes are usedaccording to water depth and/or performance of a winch. During research cruises of R/V Tansei-Maruand Shinsei-Maru, biological dredges with a 1 m span (Fig. 1) have been used. It consists of a steal
frame (1 m x 40 cm x 20 m), an inner net of 5 mm openings and an outer net of 2 cm openings. Usageof plumbic chain bridles, which swirl up mud with organisms, improves the efficiency of collecting
organisms. At deep sites, a weight is attached at the codend (the end of a net) to prevent a winch cablefrom shrinking. Of too high tension cuts a fuse wire (6 mm thickness) between bridles and a winch cable,
the dredge leaves bottom by being pulled by a life wire connecting between the winch cable and the sideof the frame to protect the winch cable and the dredge. A life wire is tied and attached the frame using
plastic tape not to become an obstacle. As dredges are drawn on sea bottom, they are often distorted andbroken due to collision with rocks. It is better to think that dredges are consumable goods. When using
a biological dredge, it is put into the sea with keeping the mouth of net upward, and lowered at a rate of
0.5 m/s from the vessel sailing at the speed through the water of 1.5 knot. Too fast lowing will loose anddamage a winch cable. Grounding of the dredge is confirmed by the decrease of the tension, which isoften rather difficult in the case of dredges, or the calculation based on the water depth, the angle of awinch cable, and the length of cable pay out. After grounding, vessel speed is changed to the ground
speed of 1.0 knot and the winch cable of 30% of the length already pay out is additionally pay out. Afterthen, the dredge is pulled at the ground speed of 1.0 knot for 5 min and wounded up at a rate of 0.2 m/s,
Guideline of ocean observations Vol. 6 Chap. 2 © Shigeaki KOJIMA 2016 G602EN:001-006

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which gradually increase to 0.5 m/s. After leaving the bottom, the dredge is wounded up at a rate of 1
m/s and recovered. During seining, the tension should be monitored. If the tension suddenly rises,
seining is terminated and the vessel is immediately stopped. On deck, samples are taken out by opening
a zipper at the side of the net. When difficult due to too much samples, it can be easily taken out by
hauling up the codend using a winch. After picking out large organisms, bottom sediment is sieved witha mesh of 1 or 4 mm to select organisms. As the mouths of dredges are rather small, collected organisms
are mainly infaunal mollusks, annelids, and echinoderms which are relatively small and less-swimming.
A dredge is not a quantifiable sampler. As deep-sea animals are patchy distributed, a small differencein sampling points often results in a large difference in amount and composition of collected animals.
So, it is difficult to estimate their density or spatial and seasonal changes based on few dredge samples.
For biological sampling on rocky bottom where biological dredge and trawl cannot be used, dredges forsampling rocks such as a cylindrical dredge are available. They are, however, seldom used to collectanimals as rocks badly damaged specimens in the dredges.

Figure 1

A biological dredge

For sampling larger benthic organisms and demersal fish with high swimming performance, trawls
are used. During cruises of R/V Tansei-Maru and Shinsei-Maru, beam trawls with a 2 m span or a 3 mspan (Fig. 2) have been used and those with a 4 m span have been used for R/V Hakuho-Maru cruises.
A beam trawl consists of two steal poles called as beams, two lateral frames called as heads, and a duplex
net. The width of the mouth of the net is fixed by beams. During seining, the frame of a trawl slides on
the sea bottom as a sledge and collect sediments near the bottom surface and animals swimming above
the bottom. As a biological dredge, a fuse wire and a life wire are used, although the latter is connectedto the codend so that the trawl is wounded up backwards abandoning sediments if the fuse wire is cut.
At the great depth such as 3,000 m, plumbic chains inserted between a winch cable and a trawl or
weight(s) attached to a frame and/or codend stabilizes the system in the sea for reliable landing. The
variation of beam trawls contain a Sigsbee-Agassiz type beam trawl, which is not distinguished between
upper and lower sides, Ocean Research Institute type beam trawl, which is distinguished between upperand lower sides, and so on. Beam trawls are operated in similar manner to biological dredges with the
exception that the vessel speed at time when a trawl is put into the sea is 2 knot through the water, a
trawl is lowered at a rate of 1 m/s, and the sampling is continued for 30 min. At the great depth, thewinch cable is pay out 70% more after grounding. If the tension rapidly decreases or does not increase
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G602EN-3

during seining, the trawl is suspected to be away from the bottom. In that case, the winch cable is pay
out additionally to see how it goes for a while. To collect demersal fish mainly, fast seining around theground speed of 1.5 knot, and slow seining around the ground speed of 0.5 knot to collect invertebrates
are recommended. In the latter case, attachment of a plumbic chain along the underside of the mouthof a net increases sampling efficiency of infauna as it sinks into the bottom sediments. As sampling areaof trawls can be calculated based on the width of the net, the seining speed, and the range between
grounding and leaving times, the density of organisms can be estimated. The value, however, tends tobe underestimated as trawls do not necessary continue to touch the bottom during seining. In order tosolve this problem, devises for real-time monitoring of status of trawls were developed (Hasumoto,2006). An otter trawl is a net sampler used mainly by research vessels of fishery institutes and training
ships of fishery high schools and colleges. They are suitable for collecting a large amount of fish andlarge crustaceans. Two steal boards named otter boards, which are set at both sides of a net, spread themouth of the net when they receive water flow from the front. Although otter trawls can collect more
samples, their quantitativty is inferior to beam trawls. As trawls have no mechanisms to close nets duringrising, the by-catch of pelagic organisms cannot be prevented and they need be selected after sampling.
Figure 2

Beam trawls with a 2 m span (left) and a 3 m span (right)

A deep-sea camera system takes photographs of deep-sea bottom. It can obtain data of organisms
inhabiting rocky bottom which cannot be sampled by trawls but can record only relatively large epifauna(organisms living on the bottom surface). Using camera(s) and a strobe contained in pressure resistantvessel(s), the system takes pictures at preprogrammed time intervals. Stereographs taken by two cameras
enable to determine sizes of organisms. A pinger is turned on just before the start of the operation andthe system is lowered at a rate of 1 m/s from drifting vessel. With approaching sea bottom, the lowing
rate is decreased and the system is kept about 2m above the bottom. Signals from the pinger are received
to monitor the distance between the system and the bottom. After photographing, the system is wounded
up at a rate of 1 m/s. Using deep-sea cameras attached to mooring systems with a disconnection devise,
temporal changes of deep-sea bottom and gathering of large organisms around baits have been observed.
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G602EN-4

3. Sampling methods of macrobenthos
Macrobenthos, which is smaller than megabenthos, is generally sampled quantitatively with bottom
sediment by using bottom samplers. During cruises of R/V Tanasei-Maru and Hakuho-Maru, 1/10 m2(Fig. 3) and 1/4 m2 Box corer (USNEL-type spade corer) have been mainly used, respectively. The
former can collect bottom sediment of surface area of 1/10 m2 and the latter can collect bottom sedimentof surface area of 1/4 m2, respectively. Both types of box corers can be used by R/V Shinsei-Maru. Box
corers are samplers which cut off bottom sediment and sea water above it as they are in a rectangularsteel box. A box is set in opened state in deck. The box corer is lowered at a rate of 1 m/s from the vessel
which holds fixed point. When landing, the box is inserted into the bottom and a spade is unclasped toturn to close the box when it is pulled out. In addition, water ports are also closed to prevent bottom
water from flowing out from the box.After confirming the box corer lands by a rapid decrease of thetension, payout of the winch cable is immediately stopped and the cable is wounded up at a rate of 0.5
m/s. In the most cases, the tension rapidly increases just before the box corer leaves the bottom, which
decreases to the ordinary level soon. Then, it is wounded up at a rate of 1 m/s and recovered. On deck,
the box is removed using a dedicated jacking dolly and bottom sediment is taken out from the upperside of the box. As a box full of mud is quite heavy, special attention is required especially on a rolling
vessel. If necessary, subcores are inserted into sediment in the box to batch off subsamples. For ananalysis of macrobenthos, the sediment is sieved with a mesh of 0.5 mm or 1 mm openings. As it is very
difficult to select all macrobenthos by the naked eyes, samples remained on the mesh are fixed by adding
neutralized formalin (final 10% in volume). In a laboratory, they are washed and sorted using astereoscopic microscope. Macrobenthic organisms are preserved in 70% ethanol. Organisms of
megabenthos-size are rarely collected by the box corer and organisms heavier than 1 g in wet weight areusually removed from data in order to prevent their presence from having a big influence on density
estimation. As mentioned below, recently multiple corers, which show superior quantitativity to box
corers, became popular. However, box corers, which can cover a larger sampling area, are still a
excellent bottom sampler for studies in macrobenthos.Figure 3  A 1/10 m2 Box corer

Before the development of a box corer, grab samplers such as a Smith-McIntyre (SM) bottom
sampler and an OKEAN grab were used to collect macrobethos from research vessels. The latter is even
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G602EN-5

now used for sapling by small ships. Bottom sediments collected by grab samplers are not uniform in
depth as those by box corers and they blow surface sediments when landing, both of which result in theunderestimation of density of organisms. Comparison among data obtained using samplers of different
types should be conducted carefully. Grab samplers contain a Ekman-Birge grab, which is so small thatit can be manage only by human power and used for sampling a small amount of bottom sediment frompiers and small ships.
In order to collect bentho-pelagic organisms, that is, animals swimming right over the sea bottom,
epibenthic sleds are used. Plankton nets within a stile frame filter sea water of the near-bottom layer
without touching the bottom, which results in damage of nets by inflow of bottom sediments. Somemodels can mechanically open nets only when the sled is landing for preventing the by-catch of pelagicorganisms and can equip video cameras (Brenke, 2005). So-called a “Manbiki (shoplifting)” net, that is,plankton nets set within a trawl net (Fig. 2, right) are also effective to collect bentho-pelagic species.
4. Sampling methods of meio- and microbenthos
Not so much as grab samplers, even box corers blow surface sediment with minute organisms at
landing. On the surface of the deep-sea bottom, amorphous materials containing fresh organic matteraccumulate to form an extremely unstable layer called as a fluffy layer in some season. Within that layer,
bacteria and unicellular eukaryotes propagate themselves. Thus, sampling loss of box corers cannot beignored in studies of smaller organisms than macrobenthos. To resolve this problem, a multiple corers
were developed by increasing quantitativity instead of reduction in sampling area (Fig. 4). It is now used
as a standard sampler of meio- and microbenthos. Disturbance of the bottom surface is minimized bylanding with “legs” grinding at remote positions from cylindrical acryl cores for the sediment collection
and inserting these tubes into the bottom very slowly. To prevent the multiple corer from leaving thebottom before the insertion completes, a winch cable is pay out a bit after landing. Then, a quarter rope
put between the winch cable and the multiple corer looses for the protection of the winch cable. A vinyl
tape is wound around the quarter rope and shackles at the both ends to avoid entwining the corer. If
bottom sediment is too soft and it overflows from the top of tubes, weights are removed from the corer
to lighten it. On deck, cores are set in opened state. The corer is lowered at a rate of 1 m/s from thevessel which holds fixed point. After the corer stands still 50 m above the bottom for 3 min to stabilize
the cable, the cable is pulled out again at a rate of 0.3 m/s (0.5 m/s if there is a strong swell). At the great
depth where the change of tension at landing is easily overlooked, a pinger is attached to cable 50m
above the corer to monitor the altitude of the corer. After landing, the winch cable is additionally (23m) pulled out. The winch cable is wounded up at a rate of 0.3 m/s 0.5-1 min later. As the case of thebox corers, the tension rapidly increases just before the corer leaves the bottom. When the tension
decreases to the ordinary level, the wounding rate is increased to 1 m/s. When landing, arms attached tolids of cores are released and cores are sealed when they are pulled out from the bottom. On deck, cores
are removed, both ends of each core are capped, and they are kept standing up. As soft sediment easily
flows out from cores, it had better be quickly held with a large spatula. After sampling, the inner part ofthe coerer and its mechanical parts such as a trigger and arms should be closely washed using fresh
water. If gravels are caught within the trigger, it results in a failure in operation. After sampling bottom
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G602EN-6

sediment containing gravels, trigger had better be released on deck to wash them away. In studies ofmeibenthos, core samples are often pushed from the lower side and sliced in parallel with the sea bottom.
In the near bottom layer with high biomass, sediment sample is sliced at small intervals (0.5-1 mm)
while intervals are wade in the deeper layer. Tools for pushing sediment out from cores have beendevised by researchers. Sliced sediment samples are foxed with neutralized formalin containing Rose
Bengal, which stains living organisms, and preserved. In laboratory, macrobenthos are removed fromsamples using a mesh of 0.5 mm or 1 mm openings and a fraction remained on a mesh of 38 ȝPRSHQLQJV
are washed. Organisms are picked up under a stereoscopic microscope and preserved in 70% ethanol.
When too much organisms are collected, they can be divided equally using a plankton divider. Samples
for studies of microbenthos are treated according to purposes suitably. Although multiple corers canobtain 3 to 8 core samples simultaneously, they are not independent. To estimate deviation of data, it isdesired to conduct repeated sampling.
Figure 4

A multiple corer

Reference
Brenke, N (2005): An epibenthic sledge for operations on marine soft bottom and bedrock. Mar. Technol. Soc.
Jour., 39, 10-19.
Hasumoto, H. (supervision㸧(2006): The Way to Observe the Ocean㸬Ocean Research Institute, The Universityof Tokyo, Tokyo, 258 pp.(in Japanese)

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G701ENr1-1

Determination of p(CO2) in air that is in equilibriumwith a continuous stream of sea water
Daisuke SASANO (Japan Meteorological Agency),
Shin-ichiro NAKAOKA (National Institute for Environmental Studies)

A standard operating procedure (SOP) of “Determination of p(CO2) in air that is in equilibriumwith a continuous stream of sea water” in Dickson, A.G., Sabine, C.L. and Christian, J.R. (Eds.) 2007,
Guide to best practices for ocean CO2 measurements, PICES Special Publication 3, is available at thefollowing website:
https://www.nodc.noaa.gov/ocads/oceans/Handbook_2007/sop05.pdf

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Appendix: Tandem type equilibrator
In the text, we introduce the shower type equilibrator, thus we here describe the tandem one.
It consists of a combination of a bubbling component with a mixer and generates theequilibrated air. The structure of the equilibrator is shown in figure 1. The flow rate of theseawater to the equilibrator is approximately 10–15 dm3 min-1. The water samples introduced
from the upper part hit plates called a mixer and are splashed. This causes the splashed water
to increase the surface area in contact with the air in the equilibrator and makes the air easier toreach equilibrium for CO2 in seawater. In addition, the air in the laboratory or the air adjusted
CO2 concentration is introduced from a bubbler attached to the lower part of the equilibrator,
then the bubbles are exchanged with CO2 in seawater to reach near equilibrium during they arerising from the bubbler to the water surface. The reason why the combination of the bubbling
and the mixer components are adopted as a tandem type equilibrator is that it is confirmed thatthe offset of CO2 concentration from the shower type equilibrator system can be eliminatedexperimentally. Although the components of the tandem type equilibrator system such as
analyzer, standard gas, dehumidification unit, etc. are quite similar to those of the shower typeone, a point that the equilibrated air is discharged out of the system after introducing theanalyzer is different from the shower type one, which makes the air circulate in the system.
Advantages of the tandem type equilibrator are that there is no clogged part like a shower headof the shower type equilibrator and that the water level in the equilibrator can be kept constant.
Consequently, they make it easy to maintain the system. On the other hand, because the size ofthe equilibrator is larger than the shower type equilibrator system, there is a disadvantage thatthe installation place is limited.

Guideline of ocean observations Vol.7 Chap.1 Determination of p(CO2) in air that is in equilibrium with acontinuous stream of sea water © Daisuke SASANO, Shin-ichiro NAKAOKA 2019 G701ENr1:001-003

G701ENr1-3

Figure 1

Schematic of the tandem type equilibrator

Guideline of ocean observations Vol.7 Chap.1 Determination of p(CO2) in air that is in equilibrium with acontinuous stream of sea water © Daisuke SASANO, Shin-ichiro NAKAOKA 2019 G701ENr1:001-003

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Acoustic Doppler Current Profilers‫ۑ‬Shinya KOUKETSU (Japan Agency for Marine-earth Science and Technology)

Shipboard acoustic Doppler current profilers (SADCPs) mounted on the hulls of sea-going vessels
have been widely used to monitor ocean currents. Downward-looking SADCPs transmit sound pulses,
measure the Doppler shifts of the reflected pulses, and then calculate the velocity of the ocean water
relative to the vessel. SADCPs with working frequencies of 38 kHz, 75 kHz, and 150 kHz have been
available from Teledyne RD Instruments (TRDI) since 2000. The lower frequency instruments canmeasure currents in deeper layers, but vertical resolution declines. According to the TRDI manual, themaximum depths of measurement and typical cell lengths for TRDI SADCPs are respectively 1000 m
and 24 m for the 38 kHz SADCP, 700 m and 16 m for the 75 kHz SADCP, and 400 m and 8 m for the
150 kHz SADCP [1]. The choice of instrument should depend on the range of water depths in the
research region. However, the maximum depth of current measurements in the field depends on local
seawater properties and may be shallower than the published maximum depth.
This guideline provides summary descriptions of data processing and field operations that arepresented in greater detail in the Global Ocean Ship-Based Hydrographic Investigations Program (GOSHIP) manual [2]. Instrument specifications, which are also provided in the GO-SHIP manual, areomitted here, but the operating principles of the SADCP are briefly described. More detailed information
about instrument configurations and applicable software should be obtained from the GO-SHIP manualor manufacturer’s manuals.
1. Measurement principles

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Figure 1 Schematic of acoustic Doppler current profiler (ADCP) observation in the x-z plane. f0 is thetransmitted pulse frequency and f1 and f2 are reflected pulse frequencies. V1 and V2 are measured velocities inthe direction of the pulses. (u, w) is the current in the x-z plane.

The pulses transmitted by the SADCP are refracted at density stratification boundaries and partiallyreflected by particles (e.g., plankton, particulate organic matter). Currents and current depths can becalculated from the Doppler shifts and periods between transmitted and reflected pulses.
If a transducer transmits a pulse of frequency f0 and the pulse is reflected by a particle moving at
velocity V1, the reflected pulse frequency (f1) is
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݂ଵ = ݂଴

Here, assuming V1 << C,

Vଵ =

஼ା௏భ
.
஼ି௏భ

݂ଵ െ ݂଴
‫ܥ‬.
2݂଴

Thus, the velocity of the current relative to the moving SADCP can be calculated from the Doppler
shift (f1 – f0). As one transducer can obtain a velocity in only one direction (transmitted pulse direction),more than three differently oriented transducers are needed to obtain a three-dimensional velocity. For
a SADCP equipped with two transducers oriented at ș° from the vertical in the x-z plane (Fig. 1) andtwo transducers oriented at ĳ° from the vertical in the y-z plane, the velocities (V1, V2, V3, V4) observed
by each transducer areVଵ = ‫ ߠݏ݋ܿ ݓ‬+ ‫ߠ݊݅ݏ ݑ‬Vଶ = ‫ ߠݏ݋ܿ ݓ‬െ ‫ߠ݊݅ݏ ݑ‬Vଷ = ‫ ߮ݏ݋ܿ ݓ‬+ ‫߮݊݅ݏ ݒ‬Vସ = ‫ ߮ݏ݋ܿ ݓ‬െ ‫߮݊݅ݏ ݒ‬
From the above equations, we obtain the three-dimensional velocity (u, v, w) relative to the moving

vessel. Although it is assumed that all four transducers measure components of the velocity of the same

current, measurements can be disturbed by small-scale current fluctuations, fish, and instrument noise.
Thus, the differences between the vertical velocities (w) estimated from different transducer pairs (e.g.,
V1 and V2 versus V3 and V4 pairs) are generally used as the “velocity error”.
2. Conversion of relative velocity to true velocity
The relative velocity measured by the SADCP should be converted to earth coordinate velocity byusing ship heading data (gyro compass or GPS compass data). This conversion can generally be doneusing software (e.g., [3] and [4]) provided by the instrument manufacturers.
To obtain the true ocean current velocity, ship velocity must be accounted for. If the water depth isshallow enough to obtain bottom track data (recorded by the SADCP), the bottom velocity can be usedas the ship velocity. Otherwise, ship velocity can be determined from GPS data.
3. Correction and evaluation of accuracy
Data obtained from individual pings are strongly disturbed by noise, and ship velocities based on GPS
data at intervals of a few minutes are not very accurate. Thus, estimates of ocean current velocities arenormally averaged over 5–10 minutes, which suppresses the influence of noise. Errors can be evaluatedon the basis of the standard deviation of the time-averaged results. However, it is important to note that
there will be large uncertainties in current velocity estimates based on data acquired during periods ofship acceleration.
Corrections are needed for the difference of the orientations of the SADCP and gyro sensor(“arrangement angle”), which can cause considerable biases between true ship velocity (usually much
faster than currents) and SADCP measurements including ship velocity. For any one cruise, comparisonof directions and magnitudes of the ship velocities obtained by SADCP bottom track with those obtained
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from GPS data allows estimation of a correction angle and amplitude coefficient for that cruise [5]. The
relationships between bottom-track velocity (ub, vb) and ship velocity (us, vs) are as follows:‫ݑ‬௦ = െߚ (‫ݑ‬௕ cos ߙ െ ‫ݒ‬௕ sin ߙ)‫ݒ‬௦ = െߚ (‫ݑ‬௕ sin ߙ + ‫ݒ‬௕ cos ߙ),

where Į is the arrangement angle DQGȕ is the amplitude coefficient. Note that the negative signs on theright-hand side of these equations indicate the direction opposite to the direction of the bottom
velocity of the ship. Using these relationships and bottom-track data obtained while cruising, thearrangement angle Į DQGDPSOLWXGHcoefficient ȕ DUHREWDLQHG as follows.
< ‫ݑ‬௕ ‫ݒ‬௦ െ ‫ݒ‬௕ ‫ݑ‬௦ >tan ߙ =< ‫ݑ‬௕ ‫ݑ‬௦ + ‫ݒ‬௕ ‫ݒ‬௦ >Ⱦ=െழ௨್ ௩ೞ ା௩್ ௨ೞ வ,మା௩್మ வୡ୭ୱ ఈழ௨್where < … > indicates the ensemble average during the cruise.
Current velocity is corrected to account for the local velocity of sound in water (‫ܥ‬௥௘௔௟ , dependent onwater temperature and salinity) by using, for example, TEOS-10 software [6] as follows:஼Vୡ୭୰୰ୣୡ୲ୣୢ = ܸ௔ௗ௖௣ ஼ ೝ೐ೌ೗ ,ೌ೏೎೛

where Vadcp and Cadcp are raw estimated current velocity and sound velocity recorded at the SADCP,
respectively. Note that vertical stratification of the water column does not affect horizontal velocities,
and that this correction is not needed if a phased array system is used (e.g., [7]).
The corresponding water depth correction is done according to the following equation:஼Lୡ୭୰୰ୣୡ୲ୣୢ = ‫ܮ‬௔ௗ௖௣ ஼ ೝ೐ೌ೗ ,ೌ೏೎೛

where Lcorrected and Ladcp are corrected and measured water depth, respectively. If the vertical profile
of Creal is available, water depths can be obtained by integration of Creal.
4. Data required for post-cruise processing
In areas where the water depth is shallow enough to use bottom tracking, the bottom-tracking data are
generally used for correction of velocity data and for evaluation of instrument noise. However, the useof bottom-track recording can reduce the accuracy of the velocity data, so bottom tracking should beturned off when working far from the coast.
The following data are needed for post-cruise data processing.
z ADCP raw dataz GPS ship location dataz Heading data based on the ship gyro (or ADCP)

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All data are collected and archived by using software provided by the equipment manufacturer (e.g.,[4] and [8]). If the GPS and gyro data collected by the vessel’s navigation systems are more accurate
than the data collected by the ADCP, they should also be archived. Although the software provided by
the manufacturer generally generates 5 or 10 minutes averaged data, the raw data (for every ping) should
also be archived for future use. Time average data can be simply generated after the cruise by using
standard PC software (e.g., [3] and [4]).
Available salinity and temperature measurements (ex. by a Conductivity Temperature Depth profiler)
should also be archived for use in sound velocity corrections.
References[1] Ocean Surveyor ADCP, Teledyne RD Instruments, http://www.rdinstruments.com/surveyor.aspx[2] Firing, E., and J.M. Hummon (2010): Shipboard ADCP measurements. The GO-SHIP Repeat Hydrography
Manual: A Collection of expart reports and guidelines, IOCP Report (14), ICPO Publication Series (134).
[3] WinADCP, Teledyne RD Instruments[4] UHDAS, University of Hawaii, http://currents.soest.hawaii.edu/uhdas_fromships.html[5] Joyce, T. M. (1989): On in situ “Calibration” of Shipboard ADCPs, J. Atmos. Oceanic Technol.,6, 169-172.
[6] Ocean Observer ADCP, Teledyne RD Instruments, http://www.rdinstruments.com/observer.aspx[7] TEOS-10, http://www.teos-10.org[8] VMDAS, Teledyne RD Instruments

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Bathymetry
Hiroshi UCHIDA (Research and Development Center for Global Change,
Japan Agency for Marine-Earth Science and Technology)
Souichiro SUEYOSHI (Nippon Marine Enterprises, Ltd.)

1. Definition and Units
Water depth is a distance measured vertically between the sea surface and the sea floor, expressedin meters (m), the base unit for distance in the International System of Units (SI). The act of measuring
water depths (bathymetry of the sea floor) is referred to as “depth sounding” or often simply as“sounding”.
Because tides cause sea level to rise and fall in time and space, the water depth shown on a chart(charted depth) is defined as the vertical distance between an appropriate reference level (chart datum)and the sea floor. In Japan, the Lowest Low Water, which is approximated by Mean Sea Level minus
the sum of the amplitudes of the four major harmonic tidal constituents (M2, S2, K1 and O1), is
selected as the chart datum to prevent stranding of vessels in coastal areas with depths shallower than
200 m (Fig. 1) (Horiuchi and Nishishita, 2010).
There are several depth sounding methods: echo sounding by measuring the two-way travel timeof an acoustic wave, wire sounding by lowering a line with a lead weight, calculation from measured
pressure and density using the hydrostatic relation, and laser induced detection and ranging (LIDAR)
by measuring the time interval between the emission of a laser pulse from an aircraft and the receptionof its reflection from the sea surface and the sea floor. Echo sounding is the standard method for
current research vessels (Japan Meteorological Agency, 1999).

Figure 1. A schematic of echo sounding.
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2. Echo Sounding
Echo sounding is a method for estimating water depths by calculation using the two-way travel
time of an acoustic pulse between a transducer on the vessel and the sea floor, and the speed of soundin seawater (Fig. 1). The equipment that uses this principle to measure water depth is called an echosounder.
Echo sounders are classified into two types: single-beam echo sounders and multi-beam echosounders (Kita et al., 2003). Single-beam echo sounders consist of one transducer that transmits asingle acoustic beam and can measure depths directly beneath the vessel. In contrast, multi-beam echosounders consist of a transducer array that transmits multiple acoustic beams and can measure depths
to each side of the vessel’s track at several ranges (Fig. 2). Sounding by multi-beam echo sounder istherefore called “swath sounding”.
The distance D between a transducer and the sea floor is expressed as

D=

ଵ ௧ଵ
‫ݐ݀ݒ ׬‬
ଶ ௧଴

,

(1)

where t0 is the time that the sound pulse is transmitted, t1 is the time that the pulse is received after
being reflected at the sea floor, and v is the speed of sound in seawater. Although v is a function ofwater temperature, salinity, and pressure, D can be estimated by using the average speed of sound ‫ݒ‬ҧover the sound path length:D=ଵ‫ݒ‬ҧ (‫ݐ‬ଵ െ ‫ݐ‬଴ ) .
ଶ(2)

A value of 1500 m/s is commonly used as a nominal value for ‫ݒ‬ҧ (Müller and Schenk, 1991). For

multi-beam echo sounders, however, the angle of the sound beam is determined on the basis of thesound speed at the transducer. It is therefore important to use the real-time sound-speed value at thetransducer to determine the beam angle because the speed can change along the vessel’s track becauseof changes in water mass or diurnal variation in sea surface temperature. The sound speed measured
by a sound-speed sensor or calculated from temperautre and salinity measurements is generally used todetermine the beam angle.
Before 2010, the speed of sound in seawater was calculated using the equation proposed by Chen
and Millero (1977) (Fofonoff and Millard, 1983). However, in “The international thermodynamic
equation of seawater—2010: Calculation and use of thermodynamic properties” (TEOS-10) (IOC etal., 2010), the equation for the speed of sound is based on the data provided by Del Grosso (1974)(Feistel, 2003). The difference between the speed of sound in seawater calculated from these two
equations is relatively small in surface water, but it becomes larger as pressure increases. The speed
calculated from the algorithm of Chen and Millero (1977) at a depth of 3000 m is about 0.5 m/s higher
than that from the equation of Del Grosso (1974). Water depths directly measured by bottom pressure
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G703EN-3

sensors were compared with water depths calculated from Eq. (2) by using two-way asoustic
travel-time data from inverted echo sounders (IES) moored about one meter above the sea floor andthe average speed of sound in seawater calculated from temperature and salinity profiles for both theChen and Millero (1977) and Del Grosso (1974) algorithms. The results showed that the algorithm of
Del Grosso (1974) is more accurate than the algorithm of Chen and Millero (1977) (Meinen and Watts,
1997).
Although higher frequency sound pulses can be used to measure water depths with higher
resolution, the sound energy in higher frequency sound pulses in seawater attenuates more rapidly thanthose of lower frequency. Therefore, a range of frequencies from 200 kHz and higher is used inshallow water and low frequency sound pulses of about 12 kHz are used for deep-water surveys,
including those in submarine trenches.

Figure 2. Schematic of echo soundings by single-beam and multi-beam echo sounders. Dotted lines representchanges in the acoustic ray due to errors in the sound-speed profile.

3. Correction of Measured Depth
To obtain the actual water depths from the depths measured between the echo-sounder transducer
and the sea floor, the following corrections are needed.
a. Draft correction
The transducer is usually on the bottom of the ship’s hull, below the sea surface. A correction is
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necessary for this depth (draft) (Fig. 1).
b. Sound-speed correction
The speed of sound in seawater changes according to changes in temperature, salinity andpressure. Therefore, it is necessary to correct for the difference between the depth calculated fromthe nominal speed of sound (Eq. 2) and the actual speed. For multi-beam echo sounders, the error
in water depth measurements may be large for the outer sound beams, because the sound pathover a vertical profile with variable sound speed bends locally toward regions of lower speed (Fig.
2). Therefore, detailed vertical profiles of sound speed are needed for the sound-speed correction.
Vertical profiles of sound speed can be obtained from a conductivity-temperature-depth (CTD)
profiler or from expendable CTD (XCTD) measurements. If CTD/XCTD data are not available
during a depth survey, CTD data from ARGO floats (robotic profiling floats) near the vessel’s
track may be useful for the sound-speed correction (Ota et al., 2011).
c. Vessel motion correction
Water depths measured by single-beam echo sounders vary as a result of the heaving, rolling, andpitching motions of the vessel. The accuracy of water depth measurements by multi-beam echosounders is also affected by the yawing (side-to-side) angular motion of the bow. Recently,
multi-beam echo sounders have included a three-axis fiber optic gyroscope with an accelerometerto precisely correct for vessel motion in real-time.
d. Tide correction
Water depth measurements should be corrected for tidal height by using tidal data. Generally,
however, the tide correction has not been applied for water depth measurements in the open ocean
because tides and tide reference levels there have been poorly understood. Because ocean tidemodels have improved markedly, mainly due to the recent accumulation of high-quality sea-level
data by satellite altimeters (Stammer et al., 2014), it is now possible to apply a tidal correction forwater depth measurements in the open ocean (Horiuchi and Nishishita, 2010).
4. Uncertainty
The International Hydrographic Organization (IHO) developed standards for hydrographic surveys
for depth soundings used to compile charts (IHO, 2008). These standards require a detailed estimationof the uncertainty in water depth data acquired by depth soundings. Both the total horizontal
uncertainty (THU) and total vertical uncertainty (TVU) must be considered as the total propagation
uncertainty (TPU) as follows.
a. Total horizontal uncertainty (THU):
࣭ Positioning system errors
࣭ Range and beam errors
࣭ The error associated with the ray path model (including the sound-speed profile) and the beam
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angle
࣭ The error in vessel heading࣭ System pointing errors resulting from transducer misalignment
࣭ Sensor location
࣭ Vessel motion sensor errors; i.e., roll and pitch࣭ Sensor position offset errors
࣭ Time synchronisation/data processing latency
b. Total vertical uncertainty (TVU):
࣭ Vertical datum errors
࣭ Vertical positioning system errors
࣭ Tidal measurement errors, including co-tidal errors where appropriate
࣭ Instrument errors
࣭ Sound-speed errors
࣭ Ellipsoidal/vertical datum separation model errors
࣭ Vessel motion errors; i.e., roll, pitch and heave
࣭ Vessel draft࣭ Vessel settlement and squat
࣭ Sea-floor slope
࣭ Time synchronisation/data processing latency
It can be useful if the uncertainty in measured water depth data also be estimated for general ocean
observations not aimed at obtaining sounding data for compiling charts. An example from the Japan
Coast Guard is helpful for showing the estimated uncertainty of measurements in the deep ocean. The
relative expanded uncertainty was about 1.0% for measurements beneath the vessels and within 2.6%
for a beam angle of 60° from the vessels for 16 cases of estimates from combinations of five research
vessels and nine multi-beam echo sounders (Oikawa et al., 2010).
The data presented in Figure 3 are an example of the uncertainty in multi-beam echo sounder dataobtained over a relatively flat sea floor under calm seas, calculated in the same way as by Oikawa et al.
(2010). As with the results of Oikawa et al. (2010), the uncertainty is higher for the wider beam angle
from the vessel. The relative expanded uncertainty was below 0.5% (25 m) when the beam angle waswithin 55°, and was about 0.1% (5 m) directly beneath the vessel, although it was only slightly higher
about 3° to each side of the vessel. Note that the uncertainties from causes such as bias and tides are
not included in this estimate because these data are from the same section of the same cruise.

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Figure 3. An example of expanded uncertainty (the coverage factor k = 2) in multi-beam echo sounderdata obtained from R/V Mirai.
The water depths measured by echo soundings can be compared with water depths calculated frompressure and density data obtained from CTD observations using the hydrostatic relation. The distance
Dp between the sea surface and the sea floor can be calculated from the hydrostatic approximation௣୫ୟ୶ 㸯

Dp = ‫׬‬଴ఘ௚݀‫ ݌‬+ Alt ,(3)

where p is the pressure, U is the density of seawater, g is the acceleration of gravity, pmax is the
maximum pressure from the CTD measurements, and Alt is the height of the CTD above the sea floor
at the maximum pressure. Alt is usually measured by an acoustic altimeter attached to the CTD using
the same principle as the echo sounder or by an acoustic pinger attached to the CTD frame. In thelatter case, the vessel’s transducer receives two acoustic signals from the pinger, one arriving directlyfrom the pinger and the other reflected by the sea floor; Alt can be calculated from the difference inarrival times of the two signals. Water depths from echo soundings were compared with water depths
calculated using Eq. (3) at CTD stations where the length of wire out during CTD measurements andthe depth calculated from CTD data (the first term on the right side of Eq. [3]) are approximately thesame (Table 1). The difference between water depths estimated by the two methods was less than
0.13%, and is approximately the same as the estimated uncertainty (0.1%) in the echo-sounder datafrom directly beneath the vessel (Fig. 3). Such precise validation of echo-sounder data is useful for
discovering unexpected problems with the data processing software or the hardware.

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Table 1. Comparison of water depths directly beneath the vessel as measured by multi-beam echosounder and calculated from CTD and acoustic altimeter data (Eq. 3). The water depths from echosoundings were estimated from Eq. (2) by using the mean speed of sound in seawater calculated
from the CTD data and corrected for the vessel’s draft (6.6 m). The data were obtained during leg 3of R/V Mirai cruise MR12-05 (Southern Ocean, 2012í2013).
StationWire out CTD

CTD height CTD depth + Echo sounding

Error in echo

number

(m)

depth

above

height above (m)sounding(m)bottom (m)bottom(m)(m)
S04I 93

4396

4395

8

4403

4406

3

S04I 94

4414

4416

9

4425

4424

í1

S04I 115

2937

2935

9

2944

2944

0

S04I 116

3934

3934

7

3941

3942

1

S04I 144

4748

4747

9

4756

4762

6

S04I 151

4834

4833

9

4842

4847

5

5. Data Management
In hydrographic surveys by research vessels, especially those including soundings by multi-beamecho sounders, it is possible to accumulate a large amount of data. The data obtained and processedmust therefore be appropriately stored at each of the following data processing stage.
a. Raw data—Echo sounding data before applying various corrections and the data used for thecorrections (e.g. sound-speed profiles), including documents (e.g. field notebooks), for future
reprocessing of the datab. Edited and corrected data—Data processed by applying any necessary noise reduction andcorrections
c. Grid point data—Data thinned by interpolation of the processed data onto grid points of theappropriate horizontal resolution
d. Metadata—A collection of data comprising, at minimum, the following information (International
Hydrographic Organization, 2008):
࣭ general information about the survey, e.g., purpose, date, area, equipment used, and name ofsurvey platform࣭ the geodetic reference system used, i.e., the horizontal and vertical datums, including tides,
within a geodetic reference frame based on the International Terrestrial Reference System(ITRS) (https://www.iers.org/IERS/EN /Science/ITRS/ITRS.html)
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࣭ calibration procedures and results (e.g. draft and vessel motion corrections)
࣭ sound-speed correction method
࣭ sounding datums (tidal correction)
࣭ estimated uncertainties and the respective confidence levels
࣭ special comments࣭ rules and mechanisms employed for data thinning

6. Noise Reduction and Gridding for Multi-Beam Echo Sounder Data
Raw data obtained by multi-beam echo sounders include outliers resulting from various factors.
Data processing software to eliminate such outliers is provided by the manufacturers of echo sounders
and those developing software for hydrographic surveys (e.g. HIPS software, Teledyne CARIS Inc.;
http://www.caris.com). Generally, outliers such as noise spikes can be eliminated visually by plotting
the lateral depth profile against the heading of the vessel over earlier profiles. Although this data
editing method is reliable, it requires considerable time and manpower for data obtained over a wide
area and in shallow waters, and the identification of noise may depend on the subjectivity of the data
editor. It is therefore important to set uniform evaluation criteria for all data editors (e.g. setting aminimum percent deviation from the water depth), based on the specifications of the echo sounderused.
Because the horizontal resolution of water depth data from multi-beam echo sounders varies
depending on spatial variations in water depth and the cruising speed of the vessel, these data are
generally interpolated onto grid points with equal horizontal intervals. To generate the grid-point data,
it is necessary to choose the horizontal interval between grid points and a method of interpolation. The
time and space intervals for the water depth data change depending on the intervals between
transmitted sound pulses (ping rate). For example, sounding data are available at 1-second intervals forshallow water with depths of several tens of meters, but they are only available at intervals of several
tens of seconds for deeper water with depths of several thousands of meters. Generally, the ping rate is
automatically determined by the echo sounder according to the water depth and the beam angle.
Therefore, appropriate horizontal intervals for grid points should be selected in consideration of thehorizontal resolution of the water depth data estimated from the ping rate in the survey area and thecruising speed. A typical method for gridding water depth data is to apply spatial averaging withinverse distance weighting by using water depth data from within a certain distance from the grid point(e.g., three or five times the horizontal grid-point interval). Also, for multi-beam echo sounders, theweighting may change in proportion to the beam angle because the uncertainty is larger for the wider
angles (Fig. 3).
For processing of multi-beam echo sounder data from hydrographic surveys in coastal waters, theCombined Uncertainty and Bathymetry Estimator (CUBE) algorithm (Calder, 2003), available in the
HIPS software, has become popular. CUBE estimates grid-point values for depth from the surrounding
data and includes estimates of uncertainty for each grid node.
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References
Calder, B. (2003): Automatic statistical processing of multibeam echosounder data. International Hydrographic
Review, 4, 53í68.
Chen, C.-T. and Millero, F. J. (1977): Sound speed of seawater at high pressures. The Journal of the AcousticalSociety of America, 62, 1129í1135.
Del Grosso, V. A. (1974): New equation for the speed of sound in natural waters (with comparison to otherequations). The Journal of the Acoustical Society of America, 56, 1084í1091.
Feistel, R. (2003): A new extended Gibbs thermodynamic potential of seawater. Progress in Oceanography, 58,
43í114.
Fofonoff, N. P. and R. C. Millard Jr. (1983): Algorithms for computation of fundamental properties of seawater.
UNESCO Technical Papers in Marine Science, 44, 53 pp.
Horiuchi, D. and A. Nishishita (2010): Examination of tidal correlation method based on ocean tide model.
Report of Hydrographic and Oceanographic Researchesí6.
International Hydrographic Organization (2008): IHO Standard for Hydrographic Surveys (5th edition). Special
publication no. 44.
IOC, SCOR and IAPSO (2010): The international thermodynamic equation of seawater – 2010: Calculation anduse of thermodynamic properties. Intergovernmental Oceanographic Commission, Manuals and Guides No.
56, UNESCO (English), 196 pp.
Japan Meteorological Agency (1999): Observations of bathymetry, Manuals for Oceanographic Observations㸪Part 1, Chapter 2, 5í8.
Kita, T., N. Kurihara, K. Hashimoto, K. Teranishi and K. Okamura (2003): A technical note regarding
bathymetric technology with particular reference to swath bathymetry. Oyo Technical Report, 23, 113í122.
Meinen, C. S. and D. R. Watts (1997): Further evidence that the sound-speed algorithm of Del Grosso is moreaccurate than that of Chen and Millero. Journal of Acoustical Society of America, 102, 4, 2058í2062.
Müller, T. J. and H.-W. Schenk (1991): Near-surface temperature, salinity, and bathymetry measurements. WHP
Operations and Methods, WHP Office Report WHPO-91-1, WOCE report no. 68/69.
Oikawa, M., N. Watanabe, T. Hashimoto, T. Yoshida and S. Chiba (2010): The uncertainties and the data
management of deep water bathymetric data obtained with multibeam echo sounders. Report ofHydrographic and Oceanographic Researches, 46, 39ï46.
Ota, H., W. Tokunaga, N. Nagahama and K. Maeno (2011): Automatic construction of sound speed profiles for
multi-beam echo sounders by using ARGO floats. Proceedings of 2011 spring meeting of Advanced Marine
Science and Technology Society.
Stammer, D., R. D. Ray, O. B. Andersen, B. K. Arbic, W. Bosch, L. Carrère, Y. Cheng, D. S. Chinn, B. D.
Dushaw, G. D. Egbert, S. Y. Erofeeva, H. S. Fok, J. A. M. Green, S. Griffiths, M. A. King, V. Lapin, F. G.
Lemoine, S. B. Luthcke, F. Lyard, J. Morison, M. Müller, L. Padman, J. G. Richman, J. F. Shriver, C. K.
Shum, E. Taguchi, Y. Yi (2014): Accuracy assessment of global barotropic ocean tide models. Reviews ofGeophysics, 52, 243í282.

Guideline of ocean observations Vol. 7 Chap. 3 Bathymetry©Hiroshi UCHIDA, Souichiro SUEYOSHI 2018 G703EN:001-009

This page left intentionally blank.

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*(1Guide to Weather Observations for Ships
Third Edition

March, 2015
Global Environment and Marine Department
Japan Meteorological Agency*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

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CONTENTS

CHAPTER 1

General Description ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ1CHAPTER 2

Observation of Atmospheric Pressure ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ6CHAPTER 3

Observation of Air Temperature and Dew-point Temperature ǱǱǱǱǱǱǱǱǱǱ9CHAPTER 4

Observation of Wind ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ16CHAPTER 5

Observation of Cloud ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ29CHAPTER 6

Observation of Visibility ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ49CHAPTER 7

Observation of Atmospheric Phenomena and Weather ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ50CHAPTER 8

Observation of Sea Surface Temperature ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ56CHAPTER 9

Observation of Ocean Waves ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ57CHAPTER 10 Observation of Sea Ice ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ61CHAPTER 11 Observation of Ice Accretion ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ69CHAPTER 12 Port Meteorological Officer (PMO) ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱ71Appendix 1 List of supplies for ship weather observations and reports ǱǱǱǱǱǱǱǱǱǱǱǱǱǱA-1Appendix 2 Table for saturated vapor pressure ǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱǱA-3*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

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CHAPTER 1

CHAPTER 1
1.1

General Description*(1

General Description

Introduction

The navigation of ships is affected by weather; consequently, methods of weather
observation have developed along with those of navigation. In fact, weather forecasting might
have originated to facilitate the safe navigation of ships. The commencement of storm
warnings in France (1856) followed an incident where allied fleets of the UK and France,
gathering off Sevastopol during the Crimean War, were suddenly enveloped by a hurricaneforce storm which wrecked several vessels (14 November 1854).
Weather observations by a ship not only benefit its own safety but that of other ships
through resultant weather forecasts and storm warnings issued using such weather reports
gathered by meteorological services. These forecasts and warnings also help prevent andreduce risks of meteorological disasters affecting industries, transport systems, livelihoods andvarious other activities on land.
Furthermore, weather reports of ships on the oceans where fewer reports are available playa valuable role in monitoring global-scale climate change, which is an increasingly important
issue for mankind affecting global warming.
The Japan Meteorological Agency (JMA), the national meteorological service of Japan,emphasizes the importance of ship weather observations. Meteorology operational services
depend on a wide-range of international co-operation. The World Meteorological Organization(WMO), one of the specialized agencies of the United Nations, promotes meteorologicalobservation on board ships under the umbrella “International Convention for the Safety of Lifeat Sea (SOLAS)” (1974). WMO has established internationally common methods of observation
including codes and procedures to report and exchange data among members of WMO.
The WMO Voluntary Observing Ship (VOS) scheme is an international program in whichships are recruited to make and report meteorological observations.
Under this scheme, JMA requests individual ships equipped with radio communication
facilities to make meteorological observations (weather observations on board ships) andreport the data by radio and mail.
This Guide explains how to make marine meteorological observations and other related
matters. In addition to this guide, JMA provides VOSs with the following materials free ofcharge:- Guide to Ships’ Weather Reports- Ships’ Weather Code Card
- Table for Finding the Dew-point- JMA Cloud Plate- Beaufort Scale of Wind Force-OBSJMA (software to make weather reports)- OBSJMA Operation Manual- Ship’s Weather Observation Field Note for OBSJMA (see Fig. 1.1)
- Marine Meteorological Logbook*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

1

CHAPTER 1

General Description*(1

- Envelope to send logbooks, floppy disks or CD-Rs (postage free within Japan)(see Appendix 1)

1.2

Careful practice1.2.1 Accurate observations
In order to obtain reliable data, it is important for mariners to perform meteorologicalobservations carefully and rigorously. An inaccurate reported observation may result in anerroneous forecast, whereas one that is valid and reliable could shed light on obscure andcomplex meteorological phenomena. It is also necessary to ensure that observations are notaffected by motion or vibration of the ship, exhaust of gases or liquids, or sea spray. Needlessto say, neglecting a scheduled observation should be avoided.
It is worthwhile matching observed values to the context of surrounding meteorologicaland ocean conditions. For example, change in atmospheric pressure. If a tropical cyclone (e.g.
typhoon) or an extra-tropical cyclone is approaching, “wind speed” will increase. If a front isapproaching, “direction of wind” will change and “wind waves” will be higher. Being mindfulof these factors will reduce errors in reading measures and help determine malfunctioning
instruments.
Observed results should be recorded directly in the Marine Meteorological Logbook. As foritems requiring calculations (see the corresponding chapters for details), it is recommended torecord observed and calculated values on paper at time of determination before making anentry in the logbook:- Atmospheric pressure; correct to sea level (Chap.2)- Dew-point temperature (Chap. 3)* dew-point hygrometer, no calculation needed- Wind speed/direction; observed (apparent) values, correct to true wind (Chap.4)- Weather (present and past); change during previous 3 or 6 hours required, change should
be recorded at any time (Chap.7)

Do not enter any value from memory. Always ensure observation procedures, calculations,and radio weather messages are correct.
Software to make electric logbooks including OBSJMA can assist in accurate weather
observations and reports.

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2

CHAPTER 1*(1General Description

5JKR·U9GCVJGT1DUGTXCVKQP(KGNF0QVG
Observation Time and Place
Year

Month

Non-instrumental Observations

Day

Hour

(JST)

Day

Hour

(UTC)

Latitude (LaLaLa) Longitude (LoLoLoLo)㼻㻌 㻌 㻌 䈓㻌㼻㻌 㻌 㻌 㻌 䈓㻌

N

E

Ship
Direct. (Ds)

Speed (vs)3hours average

3hours average

Wind Wave

W(Pw)

Height(Hw)

Visibility (VV)

kt

s

(Pw1)

m

(Hw1)

s

Type
Total Cloud
Amount (N)

Υ

/10

Dew-Point
Temp. (Td)

Lowest Cloud
Amount (Nh)Υ

/10

Direct. (dd)° Direct.

°Cause (Is)

Speed (ff)kt Speed

kt
°

Υ

hPa

(CH)

Middle
(CM)
m
Lower
(CL)

Apparent Windm

Ice Accretion on Ships

Sea Surface Temperature (Tw) Ship¶s Heading
Ship¶s Speed

Relative
Humidity

Thickness (EsEs)
cm

Stage ofDevelopment (Si)Land Origin (bi)Trend over 3hours (zi)Bearing of Ice Edge (Di)㸣Rate (Rs)Sea Ice
Concentration (ci)kt°䉝㻌 Ship¶s Course

Remarks

Height (h)

Upper

Υ

by the Dew-point Hygrometer

True Wind

m

(W2)

Cloud

hPa

Temperature (T)(Hw2)

Past WeathermDry-bulb Temp. (T) Wet-bulb Temp. (Tb)

Amount (ppp)

s

(W1)

Temperature and Humidity

Pressure Tendency

(Pw2)

m

Present Weather (ww)by Dry- and Wet-bulb

Type (a)°(dw2)

Instrumental Observations
Air Pressure (PPPP)
read

Swell 2°

(dw1)

Period°S

Swell 1

Direct.



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4PPPP

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include in PLANE LANGUAGE when special phenomena are observed.

㹇㹁㹃(via INMARSAT B) 㸬
㸬
㸬
㸬
㸬


Remarks:

The dark shaded groups are mandatory for a weather message.

Fig. 1.1 Ship’s Weather Observation Field Note for OBSJMA

1.2.2 Non-instrumental observations
Non-instrumental observations including those of weather, cloud, and visibility are asimportant as those with instruments in analysis of meteorological phenomena to forecast the
movement and scale of tropical or extra-tropical cyclones. As few research vessels conduct
ocean wave observations with instruments, non-instrumental observations from merchantships are indispensable for the analysis and forecast of ocean waves. The accuracy of noninstrumental observations relies upon the personal judgment and experience of the observer. A
fundamental requirement of modern meteorology is that observations follow the sameprocedures all over the world for reliable comparison. Therefore, it is very important to follow
the instructions and procedures indicated in this Guide or other materials mentioned in 1.1.
1.2.3 Reporting schedule
JMA requests Japanese ships navigating in area (1) in Fig. 1.2 to report their observations at
00, 03, 06, 09, 12, 15, 18 and 21 Universal Time Coordinated (UTC). Ships in area (2) arerequested to report observations at 00, 06, 12 and 18 UTC. Weather reports from VOSs arerequested to be conducted four times a day at 00, 06, 12 and 18 UTC even outside of the above
areas and reported to JMA.

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CHAPTER 1

General Description*(1

Fig. 1.2 The areas where ships are requested to report weather observations by JMA

1.2.4 Sequence of observations
Although different observations cannot be conducted simultaneously, they should be
conducted as close to the reporting time as possible. Non-instrumental observations should bemade consecutively rather than instrumental and non-instrumental alternately, since eyes needtime to accommodate to the sight over the sea (especially at night). Instrumental observations
requiring the use of a light should be made after non-instrumental ones, so that dark
adaptation of eyes is not impaired.
With the above remarks in mind, the following sequence of observations is recommended:
1) Observation of sea surface temperature (in case of bucket measurement)
2) Non-instrumental observations- Horizontal visibility- Cloud (amount, type, height, etc.)- Ocean waves (wind waves, swell)- Wind direction and speed (in case of observation by Beaufort scale)3) Instrumental observations- Wind direction and speed (in case of observation by anemometer)-Air and wet-bulb temperatures (in case of wet-bulb thermometer) or
air temperature and dew-point (in case of dew-point hygrometer)- Sea surface temperature (in case of intake measurement or hull-attached thermometer)- Atmospheric pressure to be measured exactly on time4) Calculation and conversion to codes*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

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CHAPTER 1

General Description*(1

5) Entry in Marine Meteorological Logbook
6) Preparation of Radio Weather Message7) Completion and transmission of weather report
Present and past weather should be observed as necessary (see 1.2.1). Software to makeweather reports including OBSJMA can assist in the above procedures 4) - 6).

1.3

Utilization of observed results

JMA receives weather reports from ships directly through Radio Weather Messages and/or
later through Marine Meteorological Logbooks mailed from Japanese ports.
Observations reported through Radio Weather Messages are immediately utilized mainly
to produce weather and ocean wave forecasts/warnings, and numerical weather and ocean
wave prediction models. Observations on board ships are valuable to augment the sparse data
available over the oceans. Though meteorological satellites provide observations, these data
are insufficient and require corrections based upon observations provided by ships.
Marine meteorological observation data received by JMA as Marine Meteorological
Logbooks are archived electronically after being checked for quality, and exchanged
internationally to assemble the global database of marine meteorology. These data are being
utilized for such activities as monitoring global climate change, development or improvementof numerical climate models and more.

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5

CHAPTER 2

CHAPTER 2

Observation of Atmospheric Pressure*(1Observation of Atmospheric Pressure

It is widely known from weather maps that atmospheric pressure is the most basic measureused to describe the state of the atmosphere. The distribution or time change of atmosphericpressure is an important indicator of change of weather and/or wind.

2.1 Definition and units
Hecto-pascal (hPa) is the standard unit of atmospheric pressure. Other units include mb,
mmHg and inchHg as below:
1 hPa = 100 Pa = 1 mb
1 mmHg = 1.33322 hPa
1 inchHg = 33.8639 hPa
A detailed list converting mmHg to hPa is provided in “Guide to Ships’ Weather Reports”
issued by JMA.

2.2 Measuring instruments and installation conditions
The marine aneroid barometer measures atmospheric pressure. The marine aneroid
barograph records barometric tendencies (e.g. rate of change). The resonator digital barometer,
as described later, also records atmospheric pressure and barometric tendencies.
When installing these instruments the following conditions should be considered:
1) Avoid exposure to direct sunlight.
2) Choose sites with minimum temperature change.
3) Minimize effects of vibration and shock caused by engine and/or ocean waves, withinsulation material such as sponge rubber.
4) The marine aneroid barometer is normally installed horizontally. If fixed on a verticalwall, ensure its indicated value differs no more than 0.5 hPa from that of normal
installation.

2.3 Aneroid barometer
The aneroid barometer works on the principle that its capsule made of metal expands orcontracts in response to change in atmospheric pressure. A high quality precision marine
aneroid barometer (see Fig. 2.1) is recommended for weather observations by ships.
Before reading the atmospheric pressure, tap the glass face with your finger so that theneedle vibrates slightly. Then focus your best eye above the needle and read the scale. Only use
one eye to avoid parallax error. If you see a reflection of your eye in the glass exactly at thesame horizontal position as the needle, your eye is correctly located for observation. If yourbarometer has a mirror on the scale plate, you can accurately adjust your eye position.
Among high ocean waves, ships undergo large rolling and pitching resulting in
displacement and vertical acceleration causing the barometer needle to show horizontal
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6

CHAPTER 2

Observation of Atmospheric Pressure*(1

the scale and take the average value as the observed value.
Observation of the atmospheric pressure should be made exactly on the observation hour
and the pressure should be recorded to within 0.1 hPa.

2.4 Electronic barometers
Two types of electronic barometers are commonly used for weather observations. One is aresonator digital barometer and the other an electric capacitance barometer. The former works
on the principle that the frequency of its sensor varies with atmospheric pressure. The latterworks on the principle that its electric capacitance varies with atmospheric pressure. Electronic
barometers do not indicate current atmospheric pressure but an averaged value over a shortperiod. Thus, accurate observations may be made during rolling and pitching. In addition,
since these barometers display digitized values inter- and intra-observer bias is avoided.

2.5 Correction for instrumental error
The indicated value of a barometer differs from the true value to some extent. This intrinsic
difference is known as “instrumental error” and should be corrected to obtain the station value(see 2.6) of atmospheric pressure. If the correction value for instrumental error is known from abarometer inspection, the station pressure is obtained by adding the value to the indicatedvalue. Barometers should be inspected every 6 months by Port Meteorological Officers (PMOs)
to maintain their accuracy (Chap.12).

2.6 Correction to sea level
The atmospheric pressure at mean sea level may be derived from the observed value of the
instrument installed at a height above mean sea level (referred to as station pressure). This
derivation is called “correction to mean sea level”. Correction depends not only on the heightat which the instrument is installed but on station pressure㸨 and temperature. See “Guide to
Ships’ Weather Reports” for a detailed correction table.
The height of the barometer above mean sea level should be determined when a ship isfully loaded and unloaded. If the ship draught level varies by + or - 1 m around the averagelevel, the height of the barometer above the average draught level may be taken as its height
for the correction.
Given a station pressure of 997.4 hPa, height of barometer above mean sea level of 6 m, andtemperature 13ÝC, the correction value will be 0.7 hPa according to the table mentioned above.
And the corrected value is obtained as follows:
997.4(station pressure)

+

0.7

=

(correction)

998.1 hPa(pressure at mean sea level)

2.7 Barograph
A barograph is used to check observed values of pressure and record barometric tendencies.
㸨

Station pressure is defined as the pressure at barometer level.
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7

CHAPTER 2

Observation of Atmospheric Pressure*(1Figure 2.2 shows an aneroid barograph, one of several available types of barographs. The
barograph paper, on which a continuous record of the pressure is made, is the barogram.
Barograms must be renewed at intervals (from 1 day to 7 days, depending on the instrument).
It is recommended that a barograph be installed to reveal whether a high, a low, a trough or aridge is approaching or moving away indicating improving or worsening weather conditions.
As for where and how to install the barograph, refer to section 2.2.

Fig. 2.1 Aneroid barometer

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CHAPTER 3

CHAPTER 3

Observation of Air Temperature and Dew-point Temperature*(1Observation of Air Temperature and Dew-point
Temperature

The horizontal distribution of temperature in the atmosphere caused by latitudinaldifferences in incoming sunlight creates regional differences in atmospheric density giving riseto air flow (wind), clouds and precipitation. Therefore, atmospheric temperature is one of thebasic elements to be observed in analyzing atmospheric conditions.
Water vapor in the atmosphere is the source of clouds and precipitation. It also transports
energy in the form of latent heat through evaporation and condensation. Since water vapor
absorbs and emits infrared radiation, it also affects the variation of atmospheric radiation.
Therefore water vapor plays an important role in atmospheric phenomena.

3.1 Definition and unit
The temperature of the atmosphere is called air temperature. The partial pressure of water
vapor in the atmosphere is called water vapor pressure, or vapor pressure. The maximum
value of vapor pressure in the atmosphere, which is called saturated vapor pressure, depends
on air temperature and whether the atmosphere faces water or ice. The ratio of vapor pressure
to saturated vapor pressure at a given temperature is called relative humidity. Dew-pointtemperature is defined as the air temperature at which vapor pressure is equal to saturated
vapor pressure at constant air pressure. Air and dew-point temperatures should be recorded as
degree Celsius to the nearest 0.1.

3.2 Measuring instruments and installation conditions
For observations of air and dew-point temperatures, an aspiration (ventilated)
psychrometer, an Assmann psychrometer, a sling psychrometer, and an electric psychrometer(combined resistance thermometer and dew-point hygrometer or electric humidity
hygrometer) are commonly used (see Fig. 3.1-Fig. 3.4).
A dew-point hygrometer measures the dew-point temperature directly.
A non-ventilated psychrometer is not recommended because if there is little air movement
only air near the instrument is measured, which may not represent the observation site.
An aspiration psychrometer should be screened in an instrument shelter (see Fig. 3.5).
To make accurate temperature observations, instruments should be well exposed to a fresh
air stream from the sea, which has not been in contact with or passed over the ship. They
should also be adequately shielded from spray, precipitation, and heat radiated by the sun, thesea and the ship itself.

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9

CHAPTER 3

Observation of Air Temperature and Dew-point Temperature

Fig. 3.1 Ventilated
psychrometer

Fig. 3.4

Fig. 3.2 Assmann
psychrometer*(1

Fig. 3.3 Sling
psychrometer

Fig. 3.5 Instrument shelter called “Screen”
in which a psychrometer is housed

Electric thermometer andhygrometer housed inseparate metal envelopes

3.3 Psychrometers (Dry and wet-bulb thermometers)
3.3.1 Maintenance of wet-bulb thermometer
Psychrometers are instruments with both a wet-bulb and a dry-bulb thermometer. Wetbulb temperature is measured with the wet-bulb thermometer which is a thermometer with its
bulb wrapped in a wet cloth called a sleeve (or muslin wicking). The thermometer without asleeve is called the dry-bulb thermometer. The wet-bulb thermometer is the one on the left ofan aspiration psychrometer or on the outer side of a sling psychrometer. Its sleeve must be wet
with the purest water available (preferably distilled). Any minerals or other impurities wouldchange the evaporation characteristics of the water. If the sleeve becomes dirty or contaminatedby sea spray, it should be replaced immediately. The sleeve should be renewed at least once a*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

10

CHAPTER 3

Observation of Air Temperature and Dew-point Temperature*(1

month with normal use. The thermometer bulbs should also be kept clean. When changing a
sleeve, ensure the thermometer bulbs are clean. Fig. 3.6 shows various types of wet-bulbs
wrapped in sleeves.

(Globe bulb type)(Water tank type)(Long bulb type)

Tie thesleevehere
SleeveA few threads
immersed in atank of purewater act as awick

Tie the sleeve at
the end of bulb

Fig. 3.6 Wet-bulbs wrapped in sleeves

3.3.2 Observation by psychrometer
Ten minutes before observation,
moisten the sleeve with pure
(preferably distilled) water using awater dropper careful not to wet otherparts of the psychrometer.
Higher
(25.0°C)
Eyecorrectlyaligned(24.6°C)
Lower(24.3°C)

Hold the psychrometer out of direct
sunlight, facing windward. Ensure thedry-bulb is not downwind of the wetbulb. It takes about 5 minutes to obtaina stabilized value from a wet-bulb
thermometer if the air temperature is
above 0ÝC. But it may take 10 to 20
minutes if the wet-bulb is ice covered.
Read the dry-bulb thermometer firstthen the wet-one taking care to avoid
any influence by body heat or breath.
Read the 1st decimal place of the scale
first, then the higher places.
When reading a thermometer, careshould be taken to align the eye with

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11

CHAPTER 3

Observation of Air Temperature and Dew-point Temperature*(1

the measurement point, otherwise there may be a risk of parallax error (see Fig. 3.7).
The minimum interval on a thermometer scale is generally 0.5ÝC or 0.2ÝC. For
meteorological observations, that of 0.2ÝC is recommended with the measure estimated to thenearest tenth of a degree.

3.3.3 How to measure dew-point temperature
Unless using a dew-point hygrometer, to obtain the dew-point temperature use “Table for
Finding the Dew-point” published by JMA or the table for saturated vapor pressure (seeAppendix 2).

(1) Method using “Table for Finding the Dew-point”
The table shows dew-point temperatures under wet-bulb depression values. Wet-bulb
depression is the difference between the dry-bulb temperature (t) and the wet-bulb
temperature (t’), (wet-bulb depression: t-t’). As both t-t’ and t’ are given at intervals of 0.5ÝC inthe table, the dew-point temperature is obtained as shown in the following examples:
Example A)
Given
dry-bulb temperature (t) = 20.8ÝC
wet-bulb temperature (t’) = 19.4ÝC
t-t’ = 1.4 and the nearest values at intervals of 0.5 for t’ and t-t’ are 19.5 and 1.5, respectively.
In the table we find:dew-point temperature = 18.8ÝC for t-t’ = 1.5 and t’ = 19.5.
t- t'
t’

0.5

1.0

1.5

2.0

1.4

18.8

18.5

18.3

18.0

19.5

19.3

19.0

18.8

18.5

20.0

19.8

19.5

19.3

19.1

19.0
19.4

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12

CHAPTER 3

Observation of Air Temperature and Dew-point Temperature*(1

Example B)Given
t = 1.2ÝC
t’= - 2.7ÝC (wet-bulb not ice covered)t-t’ = 3.9 and the values of t’ and t-t’ are rounded to -2.5 and 4.0, respectively. In the table(for a wet-bulb not ice covered) we find:dew-point temperature = - 12.1ÝC for t-t’ = 4.0 and t’ = - 2.5.
t-t'
t’

3.0

3.5

4.0

4.5

3.9

-9.8

-11.3

-13.0

-2.5

-9.0

-10.5

-12.1

-2.0

-8.2

-9.6

-11.1

-3.0
-2.7

-12.8

Example C)Given
t = 1.2ÝC
t’= - 2.7ÝC (wet-bulb ice covered)t-t’ = 3.9 and the values of t’ and t-t’ are rounded to -2.5 and 4.0, respectively. In the table(for a wet-bulb ice covered) we find:dew-point temperature = - 11.1ÝC for t-t’ = 4.0 and t’ = - 2.5.
t- t'
t’

3.0

3.5

4.0

4.5

3.9

-9.4

-10.7

-12.1

-2.5

-8.6

-9.8

-11.1

-2.0

-7.7

-8.9

-10.1

-3.0
-2.7

-11.5

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13

CHAPTER 3

Observation of Air Temperature and Dew-point Temperature*(1

(2) Method using “Table for saturated vapor pressure (Appendix 2)”
Appendix 2 is a series of tables to determine saturated vapor pressure from air temperature.
Different tables are used according to condition:
1) Air temperature above 0ÝC, wet-bulb not ice covered
2) Air temperature below 0ÝC, wet-bulb not ice covered
3) Air temperature below 0ÝC, wet-bulb ice covered.
To calculate dew-point temperature given dry-bulb temperature (t), wet-bulb temperature(t’), and sea level pressure (P) ast = 19.8ÝC
t’= 17.3ÝC
P = 985.2 hPa
saturated vapor pressure (E’) for t’ is 19.74 hPa from Table 1. Vapor pressure (e) is calculated as
e = E’ - A / 755 x (t-t’) x P
where A is 0.5 (wet-bulb not ice covered) or 0.44 (wet-bulb ice covered). In this case,e = 19.74 - 0.5/755 x (19.8-17.3) x 985.2= 19.74 - 1.63
= 18.11 hPa
The nearest value of (e) in the table 1) is 18.06 hPa, so its corresponding dew-point temperature
15.9ÝC should be recorded.

3.4 Electric psychrometer3.4.1 Platinum resistance thermometer
The thermometer has a platinum sensor whose resistance changes with temperature change.
It is housed in a ventilated cylinder to shield it from direct sunlight and precipitation, and toprovide adequate ventilation. Adequate wind speed ventilation for the sensor is 6 to 8 m/s.

3.4.2 Dew-point hygrometer
The sensor of the dew-point hygrometer is a heater coated with lithium chloride which
absorbs water vapor from the air. Dry lithium chloride is non-conductive but with water it
becomes conductive. As it absorbs water, conductivity increases and a current flows to theheater which evaporates water from the sensor until a dynamic equilibrium is reached when
the water vapor pressure of the lithium chloride matches that of the atmosphere. Then, thetemperature of the sensor is closely related to the dew-point temperature of the air. A
hygrometer, which generates heat, and a thermometer must be housed separately. Comparison
checks with a psychrometer should be conducted frequently. If the difference in dew-pointtemperature among them exceeds 1ÝC, apply new lithium chloride.

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14

CHAPTER 3

Observation of Air Temperature and Dew-point Temperature*(1

3.4.3 Electric humidity hygrometer
The hygrometer has a capacitance sensor including a polymer film which absorbs water. As
the polymer absorbs water there is a change in capacitance which can be directly converted to
the relative humidity of the surrounding atmosphere. The hygrometer is housed in a ventilated
cylinder to shield it from direct sunlight and precipitation. Adequate wind speed ventilation
for the sensor is about 4 m/s. Comparison checks with a psychrometer should be conducted
frequently.

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15

CHAPTER 4

CHAPTER 4

Observation of Wind*(1Observation of Wind

Wind is an important meteorological element, closely related to the pattern of atmosphericpressure. Wind speed is proportional to the pressure gradient while wind direction deviates
about 15 degrees from the direction of isobars over the oceans in mid-latitudes. Reported
observations of wind over the oceans are utilized in real time for weather analysis, forecasting
and warnings, and also as statistical data for navigation of ships and aircraft.

4.1 Definition and units
Wind vectors indicate direction (wind direction) and magnitude (wind speed). Values
averaged over 10 minutes immediately preceding the observation time should be reported. If
the wind characteristics were markedly changeable showing discontinuity during the period,
adopt the values averaged over the period since the discontinuity, hence less than 10 minutes..
Wind direction is the direction from which it is blowing. In marine meteorologicalobservation, wind direction is measured as one of 36 direction codes, with the east as 09, thesouth as 18, the west as 27 and the north as 36. The scale of the direction code increases
clockwise with an increment of 1 for each angle increment of 10 degrees. If the wind speed is
0.2 m/s (0.4 knot) or less, the wind direction should be recorded as “calm” and coded as 00 in
the logbook. If wind is indeterminate, enter 99 as the direction code.
The unit for wind speed is “knot”.
1 knot = 1 nautical mile/hour= 1852 m/hour= 0.5144 m/s
1 m/s= 1.9438 knot

Fig. 4.1

Anemometer (windvane type)Fig. 4.2 Indicator of winddirection

Fig. 4.3 Indicator of wind
speed

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16

CHAPTER 4

Observation of Wind*(1

4.2 Measuring instruments and installation conditions
A wind vane/anemometer, generally used to measure wind (Fig. 4.1), should be installed
where the wind is least affected by the ship structure and it is accessible to repair in case of
malfunction.

4.3 Measurement of wind direction and speed
With an anemograph, examine the data recorded over 10 minutes preceding theobservation time. Determine the wind direction as the averaged direction at the center of themost densely dotted part in the record. Similarly determine the mean wind speed at the centerof the fluctuating values of wind speed. Without an anemograph, determine the average ofwind direction values shown by the indicator for about 1 minute. Regarding wind speed,
discard the maximum and the minimum values and adopt the value around which fluctuations
are most constant.

4.4 Calculation of true wind direction and speed
Unless your instrument is capable of measuring wind compensating for ship motion (truewind), the observed wind obtained on board ship during navigation is taken as apparent wind.

Ship motion

Wind caused byship motion

Apparentwind

True wind

Fig. 4.4 Ship motion vector and wind vectors

True wind is the vector sum of apparent wind and ship motion. A circle graph is useful in
its calculation. Plot an angle scale on the circumference in increments of 10 degrees. Then plot a
speed scale on the diameter in increments of 10 knots. Example (Fig. 4.5) to find the true wind:*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

17

CHAPTER 4

Observation of Wind*(1

30kt
20kt

10kt
O
A

B
C

ሬሬሬሬሬሬԦ), apparent wind(ࡻ࡮ሬሬሬሬሬሬԦ), and true wind䠄ࡻ࡯ሬሬሬሬሬሬԦ䠅
Fig. 4.5 Vectors of ship motion(ࡻ࡭Given
Ship motion ( OA ):ship course, 95 degrees
ship speed, 10 knots
Apparent wind ( OB ):wind direction, 50 degrees on the port side
wind speed, 27 knots
Calculations:Mark point A at the angle of 95 degrees and distance of 10 knots from the center. The arrowfrom the center (O) to A indicates the ship motion vector.
Mark point B at the angle of 225 degrees = 95 (ship course) – 50 (apparent wind direction
relative to the bow; negative in case of wind on the port side and positive on the starboard side)+ 180 (to obtain the direction to which wind blows) and distance of 27 knots from the center.
The vector direction of apparent wind is the direction to which it is blowing, opposite fromwhich it is blowing. The arrow from the center (O) to B indicates the apparent wind vector.
The true wind vector is the summation of vectors, OB and OA . Form a parallelogramusing OA and OB to find point C. This yields OC as the true wind vector and the length of

OC as the true wind speed (22 knots). The opposite direction of OC , is the true winddirection (25 degrees) from which the wind blows. True wind can be also calculated using a*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

18

CHAPTER 4*(1Observation of Wind

wind velocity scale (see Fig. 4.6), which comprises two rotatable disks and a rectangular scale
fastened at the center. The lower disk is called the compass disk, and the upper the winddirection disk. The rectangular scale is called a wind speed ruler. To calculate true wind:1) Turn the wind direction disk to set “0” at the direction of the ship bow (95 degrees in
the above example) on the compass disk.
2) Turn the wind speed ruler to the direction of apparent wind (50 degrees to the left) on
the wind direction disk.
3) Mark point “A” on the wind direction disk using the wind speed ruler to measure windspeed (27 knots) from the center, and next, mark point “C” going down from “A” at a
distance of ship speed (10 knots) in parallel with vertical lines of the wind direction disk.
4) Turn the wind speed ruler to “C” to find the true wind speed by reading the scale of theruler at “C” (it must be 22 knots).
5) The cross point of the wind speed ruler and the wind direction disk shows the true
wind direction from the bow, and the cross point of the wind speed ruler and thecompass disk shows the true wind direction from true north (it must be 25 degrees).

Compass disk

Wind speed ruler

Wind direction disk

Fig. 4.6 Wind velocity scale

You can confirm the calculated true wind direction by observing wind waves, which travelin almost the same direction as the wind.

4.5 Non-instrument observations
If a wind vane/anemometer is unavailable wind direction and force may be found as below.

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19

CHAPTER 4

Observation of Wind*(1

4.5.1 Wind direction
True wind direction may be estimated from streaks of foam on the sea surface and/or sea(wind) wave direction with a gyro compass. Consider the following:1) Observe wind waves far enough from the ship that they are not influenced by the ship.
2) When wind direction changes abruptly, note the direction of streaks of foam and theorientation of the crests of sea waves other than their overall shape since wave
characteristics remain affected by the preceding wind for some time.
3) When wind is too weak to cause perceptible waves, estimate wind direction from thedeck considering the ship travel direction.
4) Do not rely on wind waves near shore or sea ice for proper wind direction.
5) At night or in poor visibility (such as heavy rainfall, snow, fog etc.), estimate winddirection from smoke, tape and so on.
6) Although windward is preferable, observe wind leeward to avoid dazzle by the sun or
its reflection from the sea surface.

4.5.2 Wind force
To estimate wind force from the sea surface, use the Beaufort Scale of Wind Force (see Table
4.1) and refer to photographs. The velocity equivalent in Table 4.1 is for a standard height of 10
meters above the sea surface. When using the table, heed the following:1) Even while wind is strengthening, there are time lags before changes in sea surface
characteristics (wave length, wave height, etc.) occur.
2) The scale of a wave depends on the fetch (the distance along which a wind is blowing
straight) of the wind in question. This is why a wave with land on its upstream side has
a different scale from an offshore wave.
3) If a tidal or ocean current is predominant, the sea surface does not always correspond to
the wind force. Especially, unusual waves are remarkable near an ocean front.
4) The sea depth affects the way a wave is formed.
5) When a swell is prevailing, it is more difficult to discern wind waves.
6) At night, estimation of wind force is not easy. Since it is more difficult to recognize
white caps of wind waves, slightly inflate the wind force value.
7) Rainfall tends to make the sea surface smoother. Severe rainfall is particularly effective.
In such conditions inflate the wind force value accordingly.
8) The height of a wind wave depends on the difference between air and sea surface
temperatures. Accordingly, adopt a smaller wind force value than estimated from wind
waves when the air temperature is lower than the sea surface temperature.

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20

CHAPTER 4

Observation of Wind*(1Table 4.1 Beaufort scale of wind force
Beaufort Descriptive termWind speed

numberequivalents
m/s

Specifications for observations

knots

0

Calm

0 - 0.2< 1 Sea like a mirror

1

Light air

0.3 - 1.5

1 - 3 Ripples with the appearance of scales are formed, but
without foam crests

2

Light breeze

1.6 - 3.3

4 - 6 Small wavelets, still short but more pronounced; crests
have a glassy appearance and do not break3

Gentle breeze

3.4 - 5.4

7 - 10 Large wavelets; crests begin to break; foam of glassy
appearance; perhaps scattered white horses

4

Moderate breeze

5.5 - 7.9

11 - 16 Small waves, becoming longer; fairly frequent white horses

5

Fresh breeze

8.0 - 10.7

17 - 21 Moderate waves, taking a more pronounced long form;
many white horses are formed (chance of some spray)

6

Strong breeze

10.8 - 13.8 22 - 27 Large waves begin to form; the white foam crests are more
extensive everywhere (probably some spray)

7

Near gale13.9 - 17.1 28 - 33 Sea heaps up and white foam from breaking waves begins
to be blown in streaks along the direction of the wind

8

Gale

17.2 - 20.7 34 - 40 Moderately high waves of greater length; edges of crests
begin to break into the spindrift; the foam is blown in
well-marked streaks along the direction of the wind

9Strong gale20.8 - 24.4 41 - 47 High waves; dense streaks of foam along the direction of
the wind; crests of waves begin to topple, tumble and rollover; spray may affect visibility

10

Storm

24.5 - 28.4 48 - 55 Very high waves with long overhanging crests; theresulting foam, in great patches, is blown in dense white
streaks along the direction of the wind; on the whole, thesurface of the sea takes on a white appearance; thetumbling of the sea becomes heavy and shock-like;visibility affected

11

Violent storm

28.5 - 32.6 56 - 63 Exceptionally high waves (small and medium-sized ships
might be for a time lost to view behind the waves); the sea
is completely covered with long white patches of foam
lying along the direction of the wind; everywhere theedges of the wave crests are blown into froth; visibility
affected

12

Hurricane

32.7 =<

64 =< The air is filled with foam and spray; sea completely whitewith driving spray; visibility very seriously affected*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

21

CHAPTER 4

Observation of Wind*(1*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

22

CHAPTER 4*(1Observation of Wind

Force 0 CalmWind speed < 1 knot
Sea like a mirror

Force 1

Light airWind speed 1 – 3 knots
Ripples with the appearance ofscales are formed, but without
foam crests

Force 2 Light breezeWind speed 4 – 6 knots
Small wavelets, still short but
more pronounced; crests have a
glassy appearance and do not
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23

CHAPTER 4*(1Observation of Wind

Force 3 Gentle breezeWind speed 7 – 10 knots
Large wavelets; crests begin to
break;

foam

ofglassyappearance; perhaps scattered
white horses

Force 4 Moderate breezeWind speed 11 – 16 knots
Small waves, becoming longer;
fairly frequent white horses

Force 5 Fresh breezeWind speed 17 – 21 knots
Moderate waves, taking a more
pronounced long form; many
whitehorsesare(chance of some spray)*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

24

formedCHAPTER 4*(1Observation of Wind

Force 6 Strong breezeWind speed 22 – 27 knots
Large waves begin to form; thewhite foam crests are more
extensive everywhere (probably
some spray)

Force 7 Near galeWind speed 28 – 33 knots
Sea heaps up and white foamfrom breaking waves begins tobe blown in streaks along thedirection of the windForce 8 GaleWind speed 34 – 40 knots
Moderately

high

waves

of

greater length; edges of crests
begin to break into the spindrift;
the

foam

is

blown

in

well-marked streaks along thedirection of the wind

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25*(1

CHAPTER 4*(1Observation of Wind

Force 9 Strong galeWind speed 41 – 47 knots
High waves; dense streaks offoam along the direction of thewind; crests of waves begin to
topple, tumble and roll over;spray may affect visibilityForce 10 Storm

Wind speed 48 – 55 knots
Very high waves with longoverhanging

crests;theresulting foam, in great patches,is blown in dense white streaks
along the direction of the wind;on the whole, the surface of the
sea

takes

on

a

white

appearance; the tumbling of thesea

becomes

heavy

and

shock-like; visibility affected

Force 11 Violent stormWind speed 56 – 63 knots
Exceptionally

high

waves

(small and medium-sized ships
might be for a time lost to view
behind the waves); the sea iscompletely covered with longwhite patches of foam lying
along the direction of the wind;everywhere the edges of the
wave crests are blown into
froth; visibility affected*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

26

CHAPTER 4

Observation of Wind*(1Force 12 Hurricane

Wind speed  64 knots
The air is filled with foam andspray; sea completely whitewith driving spray; visibility
very seriously affected*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

27

CHAPTER 4

Observation of Wind*(1*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

28

CHAPTER 5

CHAPTER 5

Observation of Cloud*(1Observation of Cloud

A cloud is a hydrometeor consisting of water droplets or ice crystals, or a mixture of both,suspended in the air above land or sea. It differs from fog only in that fog is in contact with theearth’s surface. Cloud observations help determine the state of the atmosphere with theirdistribution related to meteorological disturbances including Typhoons or extra-tropical lows.
Although wide range observations by meteorological satellites have been introduced, theimportance of cloud observation by ships over the oceans remains significant.

5.1 Observation of cloudObservation of cloud on board ship covers:- Amount of cloud and type of cloud- Identification of cloud types- Height of the base of each cloudObserve the total amount of cloud first, then from lower cloud to higher cloud. Among thesame height of clouds, groups with larger amount should be considered first.

5.1.1 Cloud amount (Cloud cover)“Total cloud amount” is the proportion of the sky occupied by clouds of all types.
In contrast, the proportion of a specified type of cloud is called “cloud amount” for thattype. Observers should estimate each cloud type exclusively, as if no other type were present at
different levels, taking into consideration the evolution of the sky. Total summation of thecloud amounts could then exceed the total cloud amount.
Cloud amount for any particular type is recorded as 0 if there is none present, 10 if it covers
the whole sky and 1 to 9 according to its coverage. If the amount seems too small to be 1, put 0+.
If it is almost 10 but a break is present, put 10-.
Care should be taken as follows:
1) If there is fog, haze, or other phenomena preventing observation of any cloud above,record cloud amount as unknown (sky obscured), code 9 in the logbook. If cloud can beseen through the fog, etc., cloud amount should be estimated as well as possible.
2) If the sun, moon or stars are visible through the fog, etc., and there is no evidence ofcloud above the fog, cloud amount should be estimated as 0.
3) If cloud amount cannot be estimated at night, rather than make an ambiguous guessrecord it as unknown with the code ×.
4) If part of the sky is obscured by rain or snow, decide the amount assuming the cloudbringing the rain or snow covers that part of the sky.

5.1.2 Cloud type (genus)
Clouds are classified into 10 principal types (genera), see 5.2. They are incessantly changing,*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

29

CHAPTER 5*(1Observation of Cloud

not necessarily appearing in typical form so care is needed to determine which types areprevailing. If uncertain, record as unknown.

5.1.3 Cloud height
Cloud height is the height of the cloud base above the sea measured in units of 100 m,reaching up to about 10 km. A cloud can be classified according to height as: high level cloud(CH), middle level cloud (CM) and low level cloud (CL). The maximum cloud height observed
varies according to latitude, being higher in the tropics than in the higher latitudes. If it isdifficult to discern the cloud type, consideration of its height may help.

5.2 Details of cloud types (genera)
Table 5.1 shows 10 types of clouds (genera) by 3 levels of height, and Table 5.2 summarizes
the relationship between cloud type and precipitation.

Table 5.1

Approximate heights for high, middle and low clouds

Level

Cloud type (genus)

Polar Regions

Temperate Regions

Tropical Regions

High
(CH)

Cirrus (Ci)Cirrocumulus (Cc)
Cirrostratus (Cs)

3 - 8 km5 - 13 km

6 - 18 km

Middle Altocumulus (Ac)(CM)
Altostratus (As)Nimbostratus (Ns)

2 - 4 km2 - 7 km2 - 8 km

Low
(CL)

Stratocumulus (Sc)Stratus (St)
Cumulus (Cu)
Cumulonimbus (Cb)

As: usually found in the middle level, but often extends higher.
Ns: usually found in the middle level, but often extends into theother levels.
below 2 km

below 2 km

below 2 km

Cu, Cb: usually have bases in the low level, but their tops often
reach into the middle and high levels.

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CHAPTER 5

Observation of Cloud*(1Table 5.2 Hydrometeors consisting of falling particles and the cloud genera
Genera As
Ns
Sc
St
Cu Cb
No
Hydrocloud
meteors
Rain
ʊ
ʊ
ʊ
ʊ
ʊ
Drizzle
ʊ
Snow
ʊ
ʊ
ʊ
ʊ
ʊ
ʊ
Snow grainsʊ
Snow pellets
ʊʊʊ
Diamond dust
ʊ
Hail
ʊ
Small hailʊIce pelletsʊʊ*Reference: International Cloud Atlas Vol.1 (1975)

The following descriptions of general features of each type of cloud are excerpted from
“International Cloud Atlas Vol.1 (WMO-No.407, 1975)”.

5.2.1 High level clouds (CH)(1) Cirrus (Ci)- Cirrus is defined as detached clouds in the form of white, delicate filaments or white or
mostly white patches or narrow bands. These clouds have a fibrous (hair-like) appearance, or asilky sheen, or both. Cirrus is composed almost exclusively of ice crystals. Cirrus tufts withrounded tops often form in clear air.
- At all times of day, cirrus not too close to the horizon is white, in fact whiter than any
other cloud in the same part of the sky. When the sun sinks below the horizon, cirrus high inthe sky is yellow, then pink, red and finally grey. The color sequence is reversed at dawn.
- Cirrus clouds often evolve from virga of cirrocumulus (Cc) or altocumulus (Ac), or fromthe upper part of a cumulonimbus (Cb).
- Cirrus clouds are distinguished from cirrostratus (Cs) by their discontinuous structure or,if they are in patches or bands, by their small horizontal extent or the narrowness of theircontinuous parts.

(2) Cirrocumulus (Cc)
- Cirrocumulus is defined as thin, white patch, sheet or layer of cloud without shading,composed of very small elements in the form of grains, ripples, etc., merged or separate, andmore or less regularly arranged; most of the elements have an apparent width of less than one
degree.
- Cirrocumulus is composed almost exclusively of ice crystals; strongly supercooled water
droplets may occur but are usually rapidly replaced by ice crystals.
- Cirrocumulus often forms as a result of the transformation of cirrus (Ci) or cirrostratus(Cs). Cirrocumulus may also from as the result of a decrease in size of the elements of a patch,*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

31

CHAPTER 5

Observation of Cloud*(1sheet or layer of altocumulus (Ac).
- Cirrocumulus differs from cirrus (Ci) and cirrostratus (Cs) in that it is rippled or
subdivided into very small cloudlets; it may include fibrous, silky or smooth portions which,however, do not collectively constitute its greater part.
- Cirrocumulus differs from altocumulus (Ac) in that most of its elements are very small(by definition, of an apparent width less than one degree when observed at an angle of morethan 30 degrees above the horizon) and without shading.

(3) Cirrostratus (Cs)
- Cirrostratus is defined as transparent, whitish cloud veil of fibrous (hair-like) or smoothappearance, totally or partly covering the sky, and generally producing halo phenomena.
Cirrostratus is composed mainly of ice crystals.
- Cirrostratus is never thick enough to prevent objects on the ground from casting
shadows, at least when the sun is high above the horizon.
- Cirrostratus differs from altostratus (As) by its thinness and by the fact that it may show
halo phenomena. Cirrostratus near the horizon may be mistaken for As. The slowness of theapparent movement and the slowness of the variations in optical thickness and in appearance,
both characteristic of cirrostratus, give useful guidance in distinguishing this cloud from As
and also from stratus (St).
- Cirrostratus differs from stratus (St) by being whitish throughout, and by the fact that it
may have a fibrous appearance. Moreover cirrostratus often displays halo phenomena,
whereas St does not, except occasionally at very low temperatures.
- Cirrostratus differs from a veil of haze by the fact that latter is opalescent or has a dirty
yellowish to brownish color.

5.2.2 Middle level clouds (CM)(1) Altocumulus (Ac)
- Altocumulus is defined as white or grey, or both white and grey, patch, sheet or layer ofcloud, generally with shading, composed of laminae, rounded masses, rolls, etc., which aresometimes partly fibrous or diffuse and which may or may not be merged; most of theregularly arranged small elements usually have an apparent width between one and fivedegrees.
- Altocumulus is, at least in the main, almost invariably composed of water droplets. A
corona or irisation is often observed in thin parts of altocumulus.
- An altocumulus layer may sometimes be confused with altostratus (As); in case of doubt,
clouds are called altocumulus if there is any evidence of the presence of laminae, roundedmasses, rolls, etc.
- Altocumulus, with dark portions, may sometimes be confused with stratocumulus (Sc). If
most of the regularly arranged elements have, when observed at an angle of more than 30
degrees above the horizon, an apparent width between one and five degrees, the cloud is
altocumulus.

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CHAPTER 5

Observation of Cloud*(1- Altocumulus in scattered tufts may be confused with small cumulus (Cu) clouds; thealtocumulus tufts, however, often show fibrous trails (virga) and moreover are, in theirmajority, smaller than the Cu clouds.

(2) Altostratus (As)- Altostratus is defined as greyish or bluish cloud sheet or layer of striated, fibrous or
uniform appearance, totally or partly covering the sky, and having parts thin enough to reveal
the sun at least vaguely, as through ground glass. Altostratus does not show halo phenomena.
- Altostratus is composed of water droplets and ice crystals. Raindrops or snowflakes areoften present in altostratus and below its base.
- Pannus clouds may be present; they occur under the altostratus in the lower turbulent
layers when these are moistened by evaporation from precipitation.
- Altostratus may evolve from a thickening veil of cirrostratus (Cs); it is sometimes formedby the thinning of a layer of nimbostratus (Ns). Altostratus may also develop from analtocumulus (Ac) layer; this happens when widespread ice crystal trails (virga) fall from thelatter. Sometimes, particularly in the tropics, altostratus is produced by the spreading out of the
middle or upper part of cumulonimbus (Cb).
- A low, thick layer of altostratus may be distinguished from a similar layer ofnimbostratus (Ns) by the presence in altostratus of thinner parts through which the sun is, or
could be, vaguely revealed. Altostratus is also of a lighter grey and its under surface is usuallyless uniform than that of Ns. When, on moonless nights, doubt exists regarding the choice ofthe designation altostratus or Ns, the layer is by convention called altostratus, if no rain orsnow is falling.
- Altostratus is distinguishable from stratus (St), with which it may be confused, by its
ground glass effect. Furthermore, altostratus is never white, as thin St may be when observed
more or less towards the sun.

(3) Nimbostratus (Ns)
- Nimbostratus is defined as grey cloud layer, often dark, the appearance of which isrendered diffuse by more or less continuously falling rain or snow, which in most cases reaches
the ground. It is thick enough throughout to blot out the sun. Low, ragged clouds frequently
occur below the layer, with which they may or may not merge.
- Nimbostratus is composed of water droplets (sometimes supercooled) and raindrops, ofsnow crystals and snowflakes, or of a mixture of these liquid and solid particles.
- The under surface of nimbostratus is often partially or totally hidden by pannus clouds
resulting from turbulence in the layers under its base, which are moistened by partial
evaporation of precipitation.
- In the tropics, particularly during short lulls in the rainfall, nimbostratus can be seen
breaking up into several different cloud layers, which rapidly merge again.
- Nimbostratus usually develops from thickening altostratus (As). It also sometimes forms
by the spreading out of cumulonimbus (Cb).
- Nimbostratus is distinguished from thick stratus (St) by the fact that it is a dense cloud*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

33

CHAPTER 5

Observation of Cloud*(1

producing rain, snow or ice pellets; the precipitation which may fall from St is in the form ofdrizzle, ice prisms or snow grains.
- When the observer is beneath a cloud having the appearance of a nimbostratus, but
accompanied by lightning, thunder or hail, the cloud should by convention be called
cumulonimbus (Cb).

5.2.3 Low level clouds (CL)
(1) Stratocumulus (Sc)- Stratocumulus is defined as grey or whitish, or both grey and whitish, patch, sheet or
layer of cloud which almost always has dark parts, composed of tessellations, rounded masses,
rolls, etc., which are non-fibrous (except for virga) and which may or may not be merged; mostof the regularly arranged small elements have an apparent width of more than five degrees.
- Stratocumulus is composed of water droplets. During extremely cold weather
stratocumulus may produce abundant ice crystal virga which may be accompanied by a halo.
When stratocumulus is not very thick, a corona or irisation is sometimes observed.
- Stratocumulus differs from cumulus (Cu) in that its elements usually occur in groups or
patches and generally have flat tops; if however, stratocumulus tops are in the form of domes,
they rise, unlike those of Cu, from merged bases.
- Stratocumulus is often formed by the spreading out of cumulus (Cu) or cumulonimbus(Cb).

(2) Stratus (St)- Stratus is defined as generally grey cloud layer with a fairly uniform base, which may
give drizzle, snow or snow grains. When the sun is visible through the cloud, its outline isclearly discernible. Sometimes stratus appears in the form of ragged patches.
- Stratus is usually composed of small water droplets; this cloud may, when very thin,produce a corona round the sun or moon. At low temperatures, stratus may consist of small ice
particles. The ice cloud is usually thin and may, on rare occasions, produce halo phenomena.
- A common mode of stratus formation is the slow lifting of a fog layer, due to warming of
the earth’s surface or an increase in wind speed.
- Stratus fractus clouds may also form as accessory clouds (pannus) under altostratus (As),nimbostratus (Ns), cumulonimbus (Cb) and precipitating cumulus (Cu); they develop as aresult of turbulence in the moistened layers under these clouds.
- Stratus fractus is distinguished from cumulus (Cu) fractus in that it is less white and lessdense. Furthermore, it shows a smaller vertical development, since it owes its formation mainly
to turbulence without thermal convection.

(3) Cumulus (Cu)- Cumulus is defined as detached clouds, generally dense and with sharp outlines,
developing vertically in the form of rising mounds, domes or towers, of which the bulging
upper part often resembles a cauliflower. The sunlit parts of these clouds are mostly brilliant*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

34

CHAPTER 5

Observation of Cloud*(1

white; their base is relatively dark and nearly horizontal. Sometimes cumulus is ragged.
- Cumulus is composed mainly of water droplets. Ice crystals may form in those parts of acumulus in which the temperature is well below 0ÝC; they grow at the expense of evaporatingsupercooled water droplets, thereby transforming the cloud into cumulonimbus (Cb).
- Cumulus develops in convection currents which occur when the lapse rate in the lower
layers is sufficiently steep. Such steep lapse rates result from heating of the air near the earth’s
surface.
- Since cumulonimbus (Cb) generally results from the development and transformation of
cumulus, it is sometimes difficult to distinguish cumulus with a great vertical extent from Cb.
The cloud should be named cumulus as long as the sprouting upper parts are everywhere
sharply defined and no fibrous or striated texture is apparent. If it is not possible to decide on
the basis of other criteria whether a cloud is to be named cumulus or Cb, it should by
convention be called cumulus if it is not accompanied by lightning, thunder or hail.

(4) Cumulonimbus (Cb)
- Cumulonimbus is defined as heavy and dense cloud, with a considerable vertical extent,in the form of a mountain or huge towers. At least part of its upper portion is usually smooth,or fibrous or striated, and nearly always flattened; this part often spreads out in the shape of ananvil or vast plume.
- Under the base of this cloud which is often very dark, there are frequently low ragged
clouds either merged with it or not, and precipitation sometimes in the form of virga.
- Cumulonimbus is composed of water droplets and, especially in its upper portion, of ice
crystals. It also contains large raindrops and, often, snowflakes, snow pellets, ice pellets orhailstones. The water droplets and raindrops may be substantially supercooled.
- Cumulonimbus clouds may appear either isolated clouds or in the form of a continuousline of clouds resembling a very extensive wall. In certain cases, the upper portion of
cumulonimbus clouds may be merged with altostratus (As) or nimbostratus (Ns).
Cumulonimbus may also develop within the general mass of As or Ns.
- Cumulonimbus most commonly evolves from cumulus (Cu) which was formed in thenormal manner. Cumulonimbus sometimes develops from altocumulus (Ac) or stratocumulus(Sc).

5.3 Observation of cloud states and their coding
For forecasters who eventually receive and use observers’ reports, reports on what clouds
are present in the sky are not so important but reports on distributions or arrangements ofclouds, namely the states of clouds are much more valuable.
The state of clouds is coded not only based on 10 cloud types but by the characteristics CL(low level cloud), CM (middle level cloud) and CH (high level cloud), amount, thickness,variation and combination of clouds. Procedures to define the code are shown in Figs. 5.1-5.3.
Typical photos for each code are shown in succeeding pages with explanations taken from
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35

CHAPTER 5

Observation of Cloud*(1

Fig. 5.1 Selection chart to define the code for CL)LJ6HOHFWLRQFKDUWWRGHILQHWKHFRGHIRU&0*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

36

CHAPTER 5

Observation of Cloud*(1

Fig. 5.3 Selection chart to define the code for CH*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

37

CHAPTER 5

Observation of Cloud*(1*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

38

CHAPTER 5*(1Observation of Cloud

CL : 1
Cu with little vertical extent
and seemingly flattened, or ragged Cu other than of bad weather,or both.

CL : 2
Cu of moderate or strong vertical extent, generally with protuberances in the form of domes or
towers, either accompanied or notby other Cu or by Sc, all having
their bases at the same level.

CL : 3Cb the summits of which, atleast partially, lack sharp outlines,
but is neither clearly fibrous (cirriform) nor in the form of an anvil;
Cu, Sc or St may also be present.

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39

CHAPTER 5*(1Observation of Cloud

CL : 4
Sc formed by the spreading out
of Cu; Cu may also be present.

CL : 5Sc

notresulting

from

the

spreading out of Cu.

CL : 6
St in a more or less continuous
sheet or layer, or in ragged shreds,
or both, but no St fractus of bad
weather.

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CHAPTER 5*(1Observation of Cloud

CL : 7
St fractus of bad weather or Cu
fractus of bad weather, or both(pannus), usually below As or Ns.

CL : 8
Cu and Sc other than thatformed from the spreading out of
Cu; the base of the Cu is at a different level from that of the Sc.

CL : 9Cb, the upper part of which isclearly fibrous (cirriform), often in
the form of an anvil; either accompanied or not by Cb without
anvil or fibrous upper part, by Cu,
Sc, St or pannus.

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CHAPTER 5*(1Observation of Cloud

CM : 1
As, the greater part of which issemi-transparent;

throughthispart the sun or moon may be
weakly visible, as through groundglass.

CM : 2As, the greater part of which is
sufficiently dense to hide the sunor moon, or Ns.

CM : 3Ac, the greater part of which issemi-transparent; the various elements of the cloud change only
slowly and are all at a single level.

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CHAPTER 5*(1Observation of Cloud

CM : 4
Patches (often in the form ofalmonds or fishes) of Ac, the greater

part

of

which

is

semi-transparent; the clouds occur
at one or more levels and the elements are continually changing inappearance.

CM : 5Semi-transparent Ac in bands,or Ac in one or more fairly continuous layers (semi-transparent or
opaque), progressively invading
the sky; these Ac clouds generally
thicken as a whole.

CM : 6
Ac resulting from the spreadingout of Cu (or Cb).

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CHAPTER 5*(1Observation of Cloud

CM : 7Ac in two or more layers, usually opaque in places, and not progressively invading the sky; or
opaque layer of Ac, not progressively invading the sky; or Ac together with As or Ns.

CM : 8Ac with sprouting in the formof small towers or battlements, or
Ac having the appearance of cumuliform tufts.

CM : 9Ac of a chaotic sky, generally atseveral levels.

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CHAPTER 5*(1Observation of Cloud

CH : 1
Ci in the form of filaments,
strands or hooks, not progressively invading the sky.

CH : 2
Dense Ci, in patches or entangled sheaves, which usually
do not increase and sometimes
seem to be the remains of theupper part of a Cb; or Ci withsprouting in the form of small
turrets or battlements, or Ci
having the appearance of cumuliform tufts.

CH : 3
Dense Ci, often in the form ofan anvil, being the remains of
the upper parts of Cb.

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CHAPTER 5*(1Observation of Cloud

CH : 4
Ci in the form of hooks or offilaments, or both, progressively
invading the sky; they generally
become denser as a whole.

CH : 5Ci (often in bands converging
towards one point or two opposite
points of the horizon) and Cs, or
Cs alone; in either case, they areprogressively invading the sky,and generally growing denser as awhole, but the continuous veil
does not reach 45 degrees above
the horizon.

CH : 6Ci (often in bands converging
towards one point or two opposite
points of the horizon) and Cs, or
Cs alone; in either case, they areprogressively invading the sky,and generally growing denser as awhole; the continuous veil extends
more than 45 degrees above thehorizon, without the sky being
totally covered.

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CHAPTER 5*(1Observation of Cloud

CH : 7
Veil of Cs covering the celestialdome.

CH : 8
Cs not progressively invading
the sky and not completely covering the celestial dome.

CH : 9Cc alone, or Cc accompanied
by Ci or Cs, or both, but Cc is
predominant.

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CHAPTER 5

Observation of Cloud*(1*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

48

CHAPTER 6

CHAPTER 6*(1Observation of Visibility

Observation of Visibility

Visibility is not only to what extent an object can be seen by the observer but a simple
indicator of atmospheric stability. Visibility is decreased by material in the atmosphereincluding water droplets in the form of fog, rain or snow and solid particles in the form of sanddust, smoke or crystallized salt from sea water spray. Visibility is affected by refraction anddiffusion of light due to differences in air density. Visibility observations are utilized not only
for meteorological analysis but marine traffic and management of atmospheric pollution.

6.1 Definition of visibility
Visibility (horizontal visibility) is determined as the greatest distance at which a black objectof suitable dimensions can be seen and identified against the sky at the horizon during daylightor at night if as bright as daytime, meaning visibility is constant regardless of observation time
if the atmospheric condition is unchanged.
If visibility differs by direction, adopt the shortest distance. Visibility should be observedwith the naked eye or with best corrected vision, not with a telescope, binoculars or a sextant.
See “Guide to Ships’ Weather Reports” to code observations.

6.2 Daytime observation
If a ship, island or buoy can be seen at the limit of visibility, the bestmost precise way is to
use radar to measure visibility. However, this seldom occurs so training and experience isrequired for visibility observation. One simple method is to use the relationship between height(h) of observation above the sea surface in meters and distance (L) to the horizon in kilometers.

L

 h

as shown in Table 6.1.
Table 6.1 Height of observation above sea surface and distance to the horizon
Height of observer eyes above sea level (m)

2

4

6

8

10

15

20

25

30

40

Distance of object on the horizon at sea (km)

5

7

9

10

11

14

16

18

20

23

For example, if the horizon cannot be seen clearly from a bridge 15 m above the sea surface
but can from the deck 8 m above the sea surface, visibility is about 12 km (between 14 km and
10 km in the Table).

6.3 Night-time observation
Estimation of visibility at night is not easy and requires time (from 5 to 15 minutes) to adapt
the eyes to the dark. Lights of other vessels, buildings on land and stars around the horizon
may be used to estimate visibility.

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CHAPTER 7

CHAPTER 7

Observation of Atmospheric Phenomena and Weather*(1Observation of Atmospheric Phenomena and Weather

Weather is a manifestation of the atmosphere at a particular time described by atmosphericphenomena. Atmospheric phenomena are generally classified into hydrometeors, lithometeors,
electrometeors, and photometeors. This chapter describes these atmospheric phenomena
except for photometeors, which are luminous phenomena in the atmosphere including halos,rainbows, mirages, which are unrelated to weather reports.

7.1 Atmospheric phenomena to be reported
7.1.1 Hydrometeor
Hydrometeor is a meteor comprising liquid and/or solid water particles falling through orsuspended in the atmosphere.
In the case of precipitation, report whether it is uniform (intermittent or continuous) or
shower type and whether it is rain, drizzle, snow, or hail. Shower is characterized by its sudden
beginning and ending, and generally by large and rapid changes of intensity. It is often shortlived and heavy, falling from convective clouds such as cumulus (Cu) and cumulonimbus (Cb).
Uniform precipitation falls from stratiform clouds including altostratus (As) and nimbostratus(Ns).
Various hydrometeors and their definitions are as follows:
Rain , Rain Shower : Precipitation of liquid water particles, either in the form of drops ofmore than 0.5 mm in diameter, or of smaller widely scattered drops.
Freezing Rain : Rain drops freezing on impact with the ground or ship.
Drizzle : Fairly uniform precipitation in very fine drops of water (diameter less than 0.5 mm)very close to one another, falling from stratiform clouds.
Freezing Drizzle : Drizzle drops freezing on impact with the ground or ship.
Snow , Snow Shower : Precipitation of ice crystals, isolated or clustered, falling fromclouds.
Snow Pellets : Precipitation of white and opaque ice particles, which fall from Cu and Cb
clouds and are generally conical or spherical, with diameters attaining as much as 5 mm.
Snow Grains : Precipitation of very small opaque white particles of ice and which are fairly
flat or elongated with diameters generally less than 1 mm. They usually fall in small
quantities, mostly from stratus (St) or from fog and never in the form of a shower.
Ice Pellets : Precipitation of transparent particles of ice which are spherical or irregular,
rarely conical, and which have a diameter of 5 mm or less.
Small Hail : Precipitation of translucent ice particles, which falls from Cu and Cb clouds.
These particles are almost always spherical and sometimes have conical tips. Their diameter
may attain or even exceed 5 mm
Hail : Precipitation of either transparent, or partially or completely opaque particles of ice(hailstones), usually spheroidal, conical or irregular in form and of diameter generally
between 5 and 50 mm, which fall from Cu and Cb clouds either separately or frozen
together into irregular lumps and generally accompanied by strong thunder.
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Diamond Dust : Precipitation which falls from a clear sky in very small ice crystals, often sotiny that they appear to be suspended in the air.
Fog : Suspension of very small, usually microscopic water droplets in the air, generally
reducing horizontal visibility to less than 1 km.
Ice Fog : Suspension of numerous minute ice particles in the air, reducing visibility. It
appears under air temperatures below -30ÛC and calm wind conditions.
Mist : Suspension in the air of microscopic water droplets or wet hygroscopic particles withvisibility of more than 1 km.
Spout ,: A phenomenon consisting of an often violent whirlwind, revealed by the presence ofa cloud column or inverted cloud cone (funnel cloud), protruding from the base of a Cb, andof a ´bushµ composed of water droplets raised from the surface of the sea or of dust, sand or
litter, raised from the ground.
Ice Accretion: Process by which a layer of ice builds up on a solid surface which is exposed tofreezing precipitation or supercooled droplets.
Spray <: Ensemble of water droplets torn by the wind from the surface of an extensive bodyof water, generally from the crests of waves, and carried up a short distance into the air.

7.1.2 Lithometeor
Lithometeor is meteor consisting of particles most of which are solid and dry; they are moreor less suspended in the air, or lifted by the wind from the ground.
Typical lithometeors and their definitions are as follows:
Haze : A suspension in the air of extremely small, dry particles which are invisible to thenaked eye but numerous enough to give the sky an opalescent appearance.
Smoke /: A suspension in the air of small particles produced by combustion.
Dust Storm (Sand Storm) : An ensemble of particles of dust or sand energetically lifted togreat heights by a strong and turbulent wind.
Dust Haze (Sand Haze) -: A suspension in the air of small sand or dust particles, raised fromthe ground prior to the time of observation by a dust storm or sand storm.

7.1.3 Electrometeor
Electrometeor is a visible or audible manifestation of atmospheric electricity.
Main electrometeors and their definitions are as follows:
Thunderstorm : Sudden electrical discharges manifested by a flash of light (lightning) and a
sharp or rumbling sound (thunder). Thunderstorms are associated with convective clouds(Cumulonimbus) and are, most often, accompanied by precipitation in the form ofrainshowers or hail, or occasionally snow shower, snow pellets, or small hail.
Lightning :: A luminous manifestation accompanying a sudden electrical discharge whichtakes place from or inside a cloud or, less often, from high structures on the ground or frommountains.
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CHAPTER 7

Observation of Atmospheric Phenomena and Weather*(1Thunder ;: A sharp or rumbling sound which accompanies lightning. It is emitted by rapidly
expanding gases along the channel of a lightning discharge.

7.2 Observation and recording of atmospheric phenomena
For observations of atmospheric phenomenon, record the following:1) Time of appearance2) Name of the phenomenon
3) State of the phenomenon
4) Time of ending
For state of the phenomenon, record whether the precipitation is shower or not, the level ofvisibility and intensity of the phenomenon, etc. Intensity is classified into three ranks for eachatmospheric phenomenon as described below:(1) Intensity of rain
Light: Scattered drops that do not completely wet an exposed surface, regardless of duration, toa condition where individual drops are easily seen; slight spray is observed over the decks;
puddles form slowly; sound on roofs ranges from slow pattering to gentle swishing; steadysmall streams may flow in scuppers and deck drains.
Moderate: Individual drops are not clearly identifiable; spray is observable just above deck andother hard surfaces; puddles form rapidly; sound on roofs ranges from swishing to gentle
roar.
Heavy: Rain seemingly falls in sheets; individual drops are not identifiable; heavy spray toheight of several inches is observed over hard surfaces; visibility is greatly reduced; soundon roofs resembles the roll of drums or distant roar.

(2) Intensity of drizzle
Light: Visibility 1 km or more.
Moderate: Visibility more than 0.5 km but less than 1 km.
Heavy: Visibility less than 0.5 km.

(3) Intensity of snow
Light: Visibility 1 km or more.
Moderate: Visibility more than 0.2 km but less than 1 km.
Heavy: Visibility less than 0.2 km.

(4) Intensity of hail and ice pellets
Light: Few stones or pellets falling with little, if any, accumulation.
Moderate: Slow accumulation.
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CHAPTER 7

Observation of Atmospheric Phenomena and Weather*(1Heavy: Rapid accumulation.

(5) Intensity of thunder, thunderstorm and lightning
Light thunder: Slightly perceived as distant thunder.
Moderate thunder: Thunder with considerably large sound so as to vibrate a window pane.
Heavy thunder: Thunder with deafening and astonishing sound with the effect of rattlingwindows.
Light thunderstorm: Light thunder with a flash of light.
Moderate thunderstorm: Moderate thunder with a flash of light.
Heavy thunderstorm: Heavy thunder with a flash of light.
Light lightning: Slightly perceived in the daytime and clearly visible at night.
Moderate lightning: Perceived without confrontation in the daytime and perceived from inside
a lighted room.
Heavy lightning: A flash of light brightens the surrounding area in the daytime and at night
everything is dazzled by the heavy flash of light.

7.3 Present weather and past weather
Weather should be reported by codes under present weather and past weather as describedin ´Ships· Weather Code Cardµ and ´Guide to Ship·s Weather Reportsµ.
Present weather is defined as the state of the atmosphere at the time of observation orwithin the hour (60 minutes) preceding it in some cases. Table 7.1 shows the relationshipbetween weather phenomenon and codes of present weather, total cloud amount, and visibility.
Past weather refers to the type(s) of weather which occurred for a certain period of timeprior to the observation. Table 7.2 shows the period to be covered by the past weather at eachobservation time. And Table 7.3 shows the past weather codes.

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CHAPTER 7

Table 7.1

Observation of Atmospheric Phenomena and Weather*(1

Relationship between weather phenomenon and weather report codes
Weather report codes

Weather phenomenon

Total cloud
Present weather (ww)amount(N: octas)

Clear sky



0, 1

Fine



2㹼6

Overcast(covered withmostly upper

7, 8

76

(covered withmostly lower or(except the40࣭41,

Overcast

Remarks(Ӎ1 km)

18㹼32
36㹼38

level cloud)

(VV)

Ӎ94

00㹼16


Visibility

cases of ww =40, 41)

middle levelcloud)
Haze
Dust/Sand
storm
Blowing snow



04㹼06



30㹼35



38࣭39

Fog

42㹼49

Drizzle

50㹼57

Rain

58㹼67, 80㹼82, 91, 92

Rain and snow

(unknown;either N or VV

obscured sky)must be met.
(< 1 km)

The criteria VV
must be met.

70㹼75, 77࣭78, 85࣭86

Snow

The criteria of< 94

68࣭69, 83࣭84, 93࣭94

mixed

9

ww 93 or 94 isinterpreted as hail
under warm
season and snow

93࣭94

under cold season

Small hail

79, 87࣭88, 93࣭94

Hail



89࣭90, 93࣭94

Thunderstorm

17, 95㹼99

if otherinformation is notavailable.

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CHAPTER 7

Observation of Atmospheric Phenomena and Weather*(1Table 7.2 Period to be covered by past weather
Observation time

Period00,06,12,18 UTC

Preceding 6 hours

03,09,15,21 UTC

Preceding 3 hours

Other

Preceding 1 hour
Table 7.3 Past weather codes

Code

Symbols

Description of past weather(W 1 W 2 )
0



1

    Cloud covering more than 1/2 of the sky during part of the appropriate period

Cloud covering 1/2 or less of the sky throughout the appropriate period

and covering1/2 or less during part of the period2Cloud covering more than 1/2 of the sky throughout the appropriate period3Sand storm, dust storm or blowing snow, visibility less than 1 km

4

Fog or ice fog, visibility less than 1 km; or thick haze, visibility less than 2 km

5

Drizzle

6

Rain

7

Snow, or rain and snow mixed8    Shower(s)9Thunderstorm(s)*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1
55

CHAPTER 8

CHAPTER 8

Observation of Sea Surface Temperature*(1Observation of Sea Surface Temperature

Sea surface temperature plays an important role in the interaction between the atmosphereand the ocean. The difference between the air temperature and the sea surface temperature
gives a basic measure of the vertical stability of the atmosphere and the heat exchange between
the atmosphere and the ocean.
The temperature of well mixed sea water at the depth of 1 to 2 m should be measured andrecorded to the nearest 0. 1ÝC.
Sea surface temperature is normally observed by either
1) Measuring the temperature of the condenser intake water
2) Exposing an electrical thermometer to the sea-water either directly or through the hull3) Measuring the temperature of the sea-water sampled with a sea-bucket
Methods 3) and 1) have been used for many years. Recently, as the speed and dimension ofships have increased, method 2) has been more widely used.

8.1 Intake method
The intake sea-water temperature is measured by a thermometer installed in the intake pipe.
If this requires reading in cramped conditions, the observer should guard against parallax error(Fig. 3.7). The observer should be aware that when the ship has a deep draught, or there is amarked temperature gradient in the surface layer, intake temperature may differ from thatnearer the sea surface. When the ship is stationary, sea-bucket temperature should bemeasured for comparison because the cooling water may not be circulating. Also, as
temperature of the intake pipe may be influenced by heat of the engine. This method is not thebest to observe sea-surface temperature. However, it is frequently used in consideration ofsafety and convenience.

8.2 Hull-attached thermometer method
The sensor in this method is mounted either externally in direct contact with the sea using a“through-the-hull” connection, or internally (the “limpet” type) attached to the inside of thehull. Such hull-attached thermometers provide a convenient and accurate means of measuring
sea-surface temperature. Its readout device is installed in a cabin for observation.

8.3 Sea-bucket method
In this method, the sea-bucket is lowered over the side of the ship to collect sea-water whichis hauled on board and measured by thermometer. The bucket should be filled and emptied
several times beforehand to control for the bucket temperature. The sample should be taken
near the bow, from the leeward side of the ship during navigation, from the windward side
while at anchor, and well forward of all outlets. The thermometer should be read as soon as
possible after it has attained the temperature of the water sample. The bucket should be stored
out of direct sunlight.

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CHAPTER 9

CHAPTER 9

Observation of Ocean Waves*(1Observation of Ocean Waves

Navigation of ships is profoundly affected by winds and waves. Consequently, accurate
information on ocean waves is essential for disaster prevention and economical navigation.
Recent developments in satellite technology do not diminish the importance of observations ofocean waves by ships. The data of ocean waves reported by ships contribute to the analysis andforecasting of ocean waves and statistical studies of the climatology of ocean waves.

9.1 Classification of ocean waves
There are thousands of waves with different wave heights and periods on the ocean. The
sea surface is incessantly moving up and down. Among such waves, those caused by windover the sea surface are called ocean waves and have periods from about 1 to 30 seconds.
Ocean waves are classified into wind waves (or sea) and swell. Wind waves and/or swellchange into surfs in approaching a coast, or tidal races in colliding with tidal or ocean currents.

(1) Wind waves (or Sea)
Waves raised by local wind blowing at the time of observation are usually referred to as“wind waves” or “sea”.
Development of wind waves depends on three characteristics of wind: wind speed, fetch(the distance along which a wind is blowing straight) and duration (the time during which awind with an almost fixed wind direction and speed is blowing along a fetch).
(2) Swell
Waves not raised by the local wind blowing at the time of observation, but due either towinds blowing a distance away or winds that have ceased to blow, are referred to as “swell”.
Figure 9.1 shows a schematic of wind waves (sea) with sharp crests and swell with gentle
ones.

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CHAPTER 9

Observation of Ocean Waves*(1

Fig. 9.2 Wave height (H) and wave length (L)9.2 Characteristics of ocean waves
Major characteristics of ocean wave include,
1) Wave direction: the direction from which they come.
2) Wave period: the time between the passage of two successive wave crests past a fixed
point, which is equal to wave length divided by wave speed.
3) Wave height: the vertical distance between trough and crest (see Fig. 9.2).
4) Wave length: the horizontal distance between successive crests or troughs, which isequal to wave period multiplied by wave speed (see Fig. 9.2).
5) Wave speed: the distance traveled by a wave in a unit of time, which is equal to wave
length divided by wave period.

Speed (C; unit: m/s), length (L; unit: m) and period (T; unit: second) of a wave whose
height is small compared to the ocean depth are related in theory by the following formulas:
C = 1.56T(1)

L = 0.64C2 = 1.56T2(2)

T = 0.80L1/2 = 0.64C(3)

Although the above formulae are not necessarily applicable to all types of waves, they areuseful to roughly estimate the value of each element.

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CHAPTER 9

Observation of Ocean Waves*(1

9.3 Non-instrument observation
Measures to be observed are wave direction, period and height with respect to eachdistinguishable wave among wind waves and swells traveling from various directions. Bearing
in mind the distinction between wind waves (sea) and swell, observers should differentiate
between recognizable waves, on the basis of the direction, appearance and period of the waves.
If it is difficult to observe a measure precisely due to, for example, poor light conditions, recordthat measure as unknown.

(1) Direction
The direction (one of 36) from which waves are coming, is measured from the direction ofwave trains traveling a little far from your ship with a gyrocompass. The direction of a wind
wave generally coincides with that of the local wind, but keep in mind that swells travelingfrom different directions are often combined.

(2) Period
Measurement of wave period is made in the unit of second by a stopwatch. The observer
notes an object floating on the water at some distance from the ship: if nothing better isavailable, a distinctive patch of foam can usually be found which remains identifiable for thetime required for an observation.
He starts his watch when the object appears at the crest of a wave. As the crest passes on,
the object disappears into the trough to reappear on the next crest. The time at which the object
appears at the top of each crest is noted. The observations are continued for as long as possible;
they will usually terminate when the object becomes too distant to identify, on account of the
ship’s motion. The longest observation period will be attained by choosing an object initially on
the bow as far off as it can be clearly seen.
It is possible to estimate wave period using a formula (3) where wave length is measured
based on the length of the ship.
The ratio of wave height to length is less than 1/7 in theory. For example, if a wave period
is 3 seconds, which means its length is about 14 m from the formula (2), its height must be lessthan 2 m. If observed wave height is larger, the period should be underestimated in most cases.

(3) HeightWith experience fairly reliable estimates can be made. For estimating the height of relatively
low waves, the observer should take up a position as low down in the ship as possible,
preferably amidships where the pitching is least, and on the side of the ship from which thewaves are coming. Height is measured by comparing with the known length of the ship.
In case of relatively high wave heights, by climbing up or down some steps when the ship isin a wave trough and vertical observers should position themselves where the wave crest
appears to coincide with the horizon (see Fig. 9.3 (a)). The wave height is then equal to theheight of the observer’s eyes above the level of the water. If the ship is rolling, care should betaken in the estimation as shown in Fig. 9.3 (b).

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CHAPTER 9*(1Observation of Ocean Waves

Horizontal line

Horizontal line

Fig. 9.3 Estimation of wave height at sea(a) Good example and (b) bad example*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

60

CHAPTER 10

CHAPTER 10

Observation of Sea Ice*(1Observation of Sea Ice

Several forms of floating ice may be encountered at sea, including sea ice, which resultsfrom freezing of the sea surface, and icebergs which are large pieces that have detached from a
glacier or an ice shelf. Other forms of ice include river ice which is encountered in harbors
and estuaries where it is kept in motion by tidal streams and normally presents only atemporary hindrance to ships, and lake ice. Both icebergs and sea ice can be dangerous to ships
and affect navigation. The extent of sea-ice cover may vary significantly from year to year
affecting adjacent ocean areas and weather over large areas of the world. Consequently, its
distribution is of considerable interest to meteorologists and oceanographers. Althoughknowledge of the extent of sea-ice cover has been revolutionized by satellite photography,
observations from shore stations, ships and aircraft are of great importance in corroborating
satellite observations.

10.1 Observation items
Non-instrumental observation of sea ice consists of the following items:- Concentration or arrangement of sea ice- Stage of development of sea ice- Ice of land origin- Bearing of principal ice edge
- Present ice situation and trend of conditions during past 3 hours
Observed results should be reported according to the format shown in “Guide to Ships’
Weather Reports”. To follow the Guide, refer to the definitions of technical terms in 10.2.

10.1.1 Concentration or arrangement of sea ice
Concentration or arrangement of sea ice (referred to as “ci” in the Marine Meteorological
Logbook) is expressed by code figures 0 to 9 as shown in Table 10.1. Code figures 2 to 9 are
divided into two sections depending on whether sea ice concentration within the area ofobservation is more or less uniform (code figures 2 to 5) or not (6 to 9). Concentration is theratio of the amount of sea surface covered by ice to the whole area and expressed in tenths orphrases such as “open ice” and “close ice” (see 10.2.2 (1) for details).

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CHAPTER 10

ci

Observation of Sea Ice*(1Table 10.1 Concentration or arrangement of sea ice
Concentration or arrangement of sea ice

0

No sea ice in sight1

Ship in open lead more than 1.0 nautical mile wide, or ship in fast ice with boundary
beyond limit of visibility

2

Sea ice present in concentrations
less than 3/10 concentration,
open water or very open packice

3

4/10 to 6/10, open pack ice

4

7/10 to 8/10, close pack ice

5

9/10 or more but not 10/10, very
close pack ice

Sea ice concentrationis uniform in theobservation area

Ship in ice orwithin 0.5
nautical mileof ice edge

6

Strips and patches of pack ice with
open water between

7

Strips and patches of close or very
close pack ice with areas oflesser concentration between

8

Fast ice with open water, very
open or open pack ice to seaward of the ice boundary

9

Fast ice with close or very closepack ice to seaward of the iceboundary

×

Unable to report, because of darkness, lack of visibility, or because ship is more than 0.5
nautical mile away from ice edge

Sea ice concentration
is not uniform in theobservation area

10.1.2 Stage of development of sea ice
Code figures for this item (referred to as “Si”) are determined based on the stage ofdevelopment of sea ice and its thickness as shown in Table 10.2. The ice surface color is helpful
to distinguish its stage of development such as Nilas, Young ice or First-year ice (see 10.2.1 (1)for details).

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CHAPTER 10

Si
0
1
2
3
4
5
6
7
8
9
×

Observation of Sea Ice*(1

Table 10.2 Stage of development
Stage of development
New ice only (frazil ice, grease ice, slush, shuga)
Nilas or ice rind, less than 10 cm thick
Young ice (grey ice, grey-white ice), 10-30 cm thickPredominantly new and/or young ice with some first-year ice
Predominantly thin first-year ice with some new and/or young ice
All thin first-year ice (30-70 cm thick)Predominantly medium first-year ice (70-120 cm thick) and thick first-year ice (>120 cm
thick) with some thinner (younger) first-year ice
All medium first-year ice and thick first-year ice
Predominantly medium first-year ice and thick first-year ice with some old ice(usually more than 2 m thick)Predominantly old ice
Unable to report, because of darkness, lack of visibility or because only ice of land origin
is visible or because ship is more than 0.5 nautical mile away from ice edge

10.1.3 Ice of land origin
The number of types of visible ice formed over land such as growlers, bergy bits andicebergs (see 10.2.1 (5)) for definition) are reported for this item (referred to as “bi”) andcorresponding code figures are shown in Table 10.3.
Table 10.3 Ice of land origin
bi
0
1
2
3
4
5
6
7
8
9
×

Ice of land origin
No ice of land origin
1-5 icebergs, no growlers or bergy bits
6-10 icebergs, no growlers or bergy bits
11-20 icebergs, no growlers or bergy bits
Up to and including 10 growlers and bergy bits -- no icebergs
More than 10 growlers and bergy bits -- no icebergs
1-5 icebergs, with growlers and bergy bits
6-10 icebergs, with growlers and bergy bits
11-20 icebergs, with growlers and bergy bits
More than 20 icebergs, with growlers and bergy bits -- a major hazard to navigation
Unable to report, because of darkness, lack of visibility or because only sea ice is visible

10.1.4 Bearing of closest part of the principal ice edge
This item (referred to as “Di”) reports the direction (eight points of compass) of the closest
part of the ice edge from the ship as shown in Table 10.4.

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CHAPTER 10*(1Observation of Sea Ice

Table 10.4 True bearing of principal ice edge
Di
0
1
2
3
4
5
6
7
8
9
×

True Bearing of principal ice edge
Ship in shore or flaw leadPrincipal ice edge towards North-East
Principal ice edge towards East
Principal ice edge towards South-East
Principal ice edge towards South
Principal ice edge towards South-West
Principal ice edge towards West
Principal ice edge towards North-West
Principal ice edge towards North
Not determined (ship in ice)
Unable to report, because of darkness, lack of visibility or because only ice of land origin isvisible10.1.5 Present ice situation and trend of conditions over preceding 3 hours
This item (referred to as “zi”) represents how sea ice is affecting navigation of the reporting
ship. The present status of sea ice (e.g. penetrability) and its change over the preceding 3 hours
before the observation should be reported based on Table 10.5.
Table 10.5 Present ice situation and trend of conditions over preceding 3 hourszi
0Present ice situation and trend of conditions over preceding 3 hours
Ship in open water with floating ice in sight1

Ship in easily penetrable ice; conditions improving

2

Ship in easily penetrable ice; conditions not changing

3

Ship in easily penetrable ice; conditions worsening

4

Ship in ice difficult to penetrate; conditions improving

5

Ship in ice difficult to penetrate; conditions not changing

6

Ice forming and floes freezing
togetherIce under slight pressure

7
8

Ship in ice
Ship in ice difficult topenetrate andconditions worsening

9

Ice under moderate or severepressure
Ship beset

×

Unable to report, because of darkness or lack of visibility

10.2 Terms of sea ice forms
The definitions of terms in this section are from WMO Meteorological codes “WMO Sea-ice
Nomenclature (WMO-No. 259 Edition 1970-2014).”10.2.1 Classification of sea ice forms
Sea ice form can be classified by its developing or melting stage, and as fast ice or drift ice. Iceof land origin is also distinguished from others.

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CHAPTER 10

Observation of Sea Ice*(1

(1) Development stage(a) New ice: A general term for recently formed ice which includes frazil ice, grease ice,slush and shuga. These types of ice are composed of ice crystals which are only weakly
frozen together (if at all) and have a definite form only while they are afloat.
Frazil ice: Fine spicules or plates of ice, suspended in water.
Grease ice: A later stage of freezing than frazil ice when the crystals have coagulated toform a soupy layer on the surface. Grease ice reflects little light, giving the sea a mattappearance.
Slush: Snow which is saturated and mixed with water on land or ice surfaces, or as a
viscous floating mass in water after a heavy snowfall.
Shuga: An accumulation of spongy white ice lumps, a few centimeters across; they areformed from grease ice or slush and sometimes from anchor ice rising to the surface.
(b) Nilas: A thin elastic crust of ice, easily bending on waves and swell and underpressure, thrusting in a pattern of interlocking “fingers” (finger rafting). Has a mattsurface and is up to 10 cm in thickness. May be subdivided into dark nilas and light nilas.
Dark nilas: Nilas which is under 5 cm in thickness and is very dark in color.
Light nilas: Nilas which is more than 5 cm in thickness and rather lighter in color than darknilas.
Ice rind: A brittle shiny crust of ice formed on a quiet surface by direct freezing or fromgrease ice, usually in water of low salinity. Thickness to about 5 cm. Easily broken by windor swell, commonly breaking in rectangular pieces.
(c) Pancake ice (see drift ice)(d) Young ice: Ice in the transition stage between nilas and first-year ice, 10-30 cm inthickness. May be subdivided into grey ice and grey-white ice.
Grey ice: Young ice 10-15 cm thick. Less elastic than nilas and breaks on swell. Usually rafts
under pressure.
Grey-white ice: Young ice 15-30 cm thick. Under pressure more likely to ridge than to raft.
(e) First-year ice: Sea ice of not more than one winter’s growth, developing from young ice;thickness 30 cm - 2 m. May be subdivided into thin first-year ice (white ice), medium first-year
ice (white ice first stage) and thick first-year ice (white ice second stage).
Thin first-year ice (white ice): First-year ice 30-70 cm thick.
Medium first-year ice (white ice first stage): First-year ice 70-120 cm thick.
Thick first-year ice (white ice second stage): First-year ice over 120 cm thick.
(f) Old ice: Sea ice which has survived at least one summer’s melt; typical thickness up to
3 m or more. Most topographic features are smoother than those of first-year ice. May be
subdivided into residual, second-year ice and multi-year ice.

(2) Melting stage(a) Puddle: Accumulation on ice of melt-water, mainly due to melting snow, but in theadvanced stages due to melting ice. The initial stage consists of patches of melted snow.
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65

CHAPTER 10

Observation of Sea Ice*(1(b) Thaw holes: Vertical holes in sea ice formed when surface puddles melt through to theunderlying water.
(c) Dried ice: Sea ice on the surface where melt-water has disappeared by draining
through cracks and thaw holes. During the period of drying, the surface whitens.
(d) Rotten ice: Sea ice which has become honeycombed and is in an advanced stage ofdisintegration.
(e) Flooded ice: Sea ice, which has been flooded by melt-water or river water and isheavily loaded by water and wet snow.

(3) Fast ice
Sea ice which forms and remains fast along the coast, where it is attached to the shore, to an
ice wall, to an ice front, between shoals or grounded/icebergs. Vertical fluctuations may beobserved during changes of sea-level. Fast ice may be formed in situ from sea water or byfreezing of floating ice of any age to the shore which may extend from a few meters to several
hundred kilometers from the coast. Fast ice may be more than one year old and may then be
prefixed with the appropriate age category (old, second-year, or multi-year). If it is thicker thanabout 2 m above sea-level it is called an ice shelf.
(a) Young coastal ice: The initial stage of fast ice formation consisting of nilas or young ice,with a width varying from a few meters up to 100-200 m from the shorelines.
(b) Icefoot: A narrow fringe of ice attached to the coast, unmoved by tides and remaining
after the fast ice has moved away.
(c) Anchor ice: Submerged ice attached or anchored to the bottom, irrespective of thenature of its formation.

(4) Floating ice(a) Drift ice/Pack ice: Term used in a wide sense to include any area of sea ice other thanfast ice no matter what form it takes or how it is disposed. When concentrations are high, i.e.
7/10 or more, drift ice may be replaced by the term pack ice.
(b) Pancake ice: Predominantly circular pieces of ice from 30 cm to 3 m in diameter, andup to about 10 cm thick, with raised rims due to the pieces striking against one another. It
may be formed on a slight swell from grease ice, shuga or slush or as a result of the breakingof ice rind, nilas or, under severe conditions of swell or waves, of grey ice. It also sometimes
forms at some depth at an interface between water bodies of different physicalcharacteristics, from where it floats to the surface; it may rapidly cover wide areas of water.
(c) Floe: Any contiguous piece of sea ice. Floes are subdivided according to horizontal
extent as follows:
Floe giant: Over 10 km across.
Floe vast: 2-10 km across.
Floe big: 500-2000 m across.
Floe medium: 100-500 m across.

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66

CHAPTER 10

Observation of Sea Ice*(1

Floe small: 20-100 m across.
Ice cake: Less than 20 m across.
(d) Floeberg: A massive piece of sea ice composed of a hummock, or a group of
hummocks frozen together, and separated from any ice surroundings. It may typically
protrude up to 5 m above sea-level.
(e) Ice breccia: Ice of different stages of development frozen together.
(f) Brash ice: Accumulations of floating ice made up of fragments not more than 2 m across,the wreckage of other forms of ice.

(5) Ice of land origin(a) Glacier ice: Ice in, or originating from, a glacier, whether on land or floating on the sea
as icebergs, bergy bits or growlers.
(b) Ice shelf: A floating ice sheet of considerable thickness showing 2-50 m or more above
sea-level, attached to the coast. Usually of great horizontal extent and with a level orgently undulating surface, nourished by annual snow accumulation and often also by theseaward extension of land glaciers. Limited areas may be aground. The seaward edge istermed an ice front.
(c) Calved ice of land origin:
Iceberg: A massive piece of ice of greatly varying shape, protruding more than 5 m above
sea-level, which has broken away from a glacier or ice shelf, and which may be afloat oraground. Icebergs may be described as tabular, dome-shaped, sloping, pinnacled,
weathered or glacier bergs.
Bergy bit: A large piece of floating glacier ice, generally showing less than 5 m above sealevel but more than 1 m and normally about 100-300 m2 in area.
Growler: Piece of ice smaller than a bergy bit and floating less than 1 m above the sea
surface, a glowler generally appears white but sometimes transparent or blue-green incolor. Extending less than 1 m above sea surface and normally occupying an area of about
20 m2, growlers are difficult to distinguish when surrounded by sea ice or in high sea state.

10.2.2 Terms related to occurrence of sea ice(1) Concentration
The ratio expressed in tenths describing the amount of the sea surface covered by ice as afraction of the whole area being considered. Total concentration includes all stages ofdevelopment that are present, partial concentration may refer to the amount of a particular
stage or of a particular form of ice and represents only a part of the total.
(a) Compact ice: Floating ice in which the concentration is 10/10 and no water is visible.
(b) Very close ice: Floating ice in which the concentration is 9/10 to less than 10/10.
(c) Close ice: Floating ice in which the concentration is 7/10 to 8/10, composed of floes
mostly in contact.
(d) Open ice: Floating ice in which the concentration is 4/10 to 6/10, with many leads and*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

67

CHAPTER 10

Observation of Sea Ice*(1polynyas, and the floes are generally not in contact with one another.
(e) Very open ice: Floating ice in which the concentration is 1/10 to 3/10, and water
preponderates over ice.
(f) Open water: A large area of freely navigable water in which sea ice is present inconcentrations less than 1/10. No ice of land origin is present.

(2) Arrangement(a) Ice field: Area of floating ice consisting of any size of floes, which is greater than 10 km
across.
Ice patch: An area of floating ice less than 10 km across.
(b) Strip: Long narrow area of floating ice, about 1 km or less in width, usually composedof small fragments detached from the main mass of ice, and run together under the
influence of wind, swell or current.
(c) Ice edge: The demarcation at any given time between the open sea and sea ice of any
kind, whether fast or drifting. It may be termed compacted or diffuse.
(d) Ice boundary: The demarcation at any given time between fast ice and drift ice or
between areas of drift ice of different concentrations.

(3) Openings in the ice(a) Fracture: Any break or rupture through very close ice, compact ice, consolidated ice, fast
ice or a single floe resulting from deformation processes. Fractures may contain brash ice
and/or be covered with nilas and/or young ice. Length may vary from a few meters to
many kilometers.
(b) Lead: Any fracture or passage-way through sea ice navigable by surface vessels.
(c) Polynya: Any non-linear shaped opening enclosed in ice. Polynyas may contain brash
ice and/or be covered with new ice, nilas or young ice.
Shore polynya: A polynya between drift ice and the coast or drift ice and an ice front.
Flaw polynya: A polynya between drift ice and fast ice.
Recurring polynya: A polynya, which recurs in the same position every year.

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68

CHAPTER 11

CHAPTER 11

Observation of Ice Accretion*(1Observation of Ice Accretion

Ice accretion (icing) is growth in size, particularly by accumulation, of ice formed on the
ship’s exposed surfaces. It can cause radio and radar failures due to the icing of aerials andsometimes cause a rollover due to the weight of ice. Observation of ice accretion is importantfor safe navigation.

11.1 Ice accretion on ship
Three main causes of ice accretion include
1) Spray and sea water thrown up by interaction between the ship and waves, and/or
spray blown from the crests of waves
2) Freezing rain, drizzle or fog3) Wet snow followed by a drop in temperature
Of the above, 1) poses the greatest concern for ships.
Studies on the meteorological effects on ice accretion in the western North Pacific haverevealed conditions to consider as warning signs:
In sea surface temperature below 4ÝC, ice accretion starts with air temperature below - 3ÝC
and wind speed over 8 m/s. Strong ice accretion (over 2 cm/hour) occurs with air temperature
below - 6ÝC and wind speed over 10m/s. In sea surface temperature below 2ÝC, ice accretion
starts with air temperature below - 2ÝC. The relation of air temperature and wind speed to ice
accretion is shown in Fig. 11.1. With air temperature below - 17ÝC, spray freezes before it isthrown at the ship so the rate of ice accretion reduces. If navigating in sea surface temperature
below 4ÝC and low air temperature and strong wind are expected, be careful of ice accretion on
ship.

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CHAPTER 11

Observation of Ice Accretion*(1Air

temperature (ÝC)

A: Light ice accretion
B: Moderate ice accretion
C: Dangerous heavy ice accretion

Wind speed (m/s)
Fig. 11.1

General relation among air temperature, wind speed, and ice accretion
Based on Figure 3 (b) of Sawada (1979)*

11.2 Coding of observation
11.2.1 Causes of ice accretion on ships
Causes of ice accretion (referred to as “Is” in the Marine Meteorological Logbook) should
be coded by one of five code figures (see Table 11.1 or “Ships’ Weather Code Card” for details).

11.2.2 Thickness of ice accretion
Thickness of ice accretion (referred to as “EsEs”) should be reported in centimeters. If there
are different values of thickness on a ship, the maximum value should be reported.

11.2.3 Rate of ice accretion on ships
Find the description that best applies to the rate of ice accretion at observation time(referred to as “Rs”) in Table 11.2 or “Ships’ Weather Code Card”.
Table 11.1 Ice accretion on ships code
Is Ice accretion on ships
1 Icing from ocean spray2 Icing from fog
3 Icing from ocean spray and fog
4 Icing from rain
5 Icing from ocean spray and rain

Table 11.2 Rate of ice accretion code
Rs Rate of ice accretion
0 Ice not building up
1 Ice building up slowly
2 Ice building up rapidly
3 Ice melting or breaking up slowly
4 Ice melting or breaking up rapidly* T. Sawada (1975): Relation between the Rate of Ice Accretion on Ship and Meteorological Conditions. Journal of
Meteorological Research, Vol.27, No.6, 229-236*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

70

CHAPTER 12

CHAPTER 12

Port Meteorological Officer (PMO)*(1

Port Meteorological Officer (PMO)The Port Meteorological Officer (PMO) is defined by WMO as the official of the
Meteorological Service of a WMO Member who is stationed at a main seaport with the tasks ofmaintaining liaison with weather observers on board ships, checking instruments, providing
advice, and contacting shipping authorities to enlist their cooperation in operating mobile ship
stations (weather station aboard a moving ship). The PMO visits ships to encourage them toreport weather and offers the following services free of charge:- To check and calibrate instruments equipped on ships including barometers and givenecessary advice.
- To provide instruction or assistance with regard to questions or inquiries on
meteorology or oceanography, specifically on marine meteorological observation and its
reporting.
- To explain such materials published by JMA as Marine Meteorological Logbook, Guide
to Weather Observation for Ships, Ship’s Weather Code Card, etc. If requested, the PMO
will supply necessary copies.
- To inform the schedule of radio facsimile transmission from the meteorological services
for ships and explain how to receive and utilize it.

There are three PMOs in Japan as shown below. They are in Yokohama, Nagoya and Kobe.
Similar services are also available from Sapporo, Sendai, Osaka, Fukuoka and Okinawa
Regional Headquarters of the Japan Meteorological Agency. The following E-mail address iscommon to all officers/offices.

Port Meteorological Officers
Port Meteorological Officer, Yokohama Local Meteorological Office
99, Yamate-cho, Naka-ku, Yokohama 231 -0862, JAPAN
fax: +81-45-622-3520, E-mail: pmo@climar.kishou.go.jp
Port Meteorological Officer, Nagoya Local Meteorological Office
2-18, Hiyori-cho, Chikusa-ku, Nagoya 464 -0039, JAPAN
fax: +81-52-762-1242, E-mail: pmo@climar.kishou.go.jp
Port Meteorological Officer, Kobe Local Meteorological Office
1-4-3 Wakinohamakaigan-Dori, Chuo-ku, Kobe 651-0073, JAPAN
fax: +81-78-222-8946, E-mail: pmo@climar.kishou.go.jp*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

71

CHAPTER 12

Port Meteorological Officer (PMO)*(1Other Port Meteorological Service Offices
Climate and Marine Division, Sapporo Regional Headquarters, Japan Meteorological
Agency18-2 Kitanijo-nishi, Chuo-ku, Sapporo 060-0002, JAPAN
fax: +81-11-611-3206, E-mail: pmo@climar.kishou.go.jp
Climate and Marine Division, Sendai Regional Headquarters, Japan Meteorological Agency
1-3-15 Gorin, Miyagino-ku, Sendai 983-0842, JAPAN
fax: +81-22-291-8110, E-mail: pmo@climar.kishou.go.jp
Climate and Marine Division, Osaka Regional Headquarters, Japan Meteorological Agency
4-1-76 Otemae, Chuo-ku, Osaka 540-0008, JAPAN
fax: +81-6-6949-6160, E-mail: pmo@climar.kishou.go.jp
Climate and Marine Division, Fukuoka Regional Headquarters, Japan Meteorological
Agency1-2-36 Ohori, Chuo-ku, Fukuoka 810-0052 JAPAN
fax: +81-92-761-1726, E-mail: pmo@climar.kishou.go.jp
Climate and Marine Division, Okinawa Regional Headquarters, Japan Meteorological
Agency1-15-15 Higawa, Naha 900-8517, JAPAN
fax: +81-98-833-4292, E-mail: pmo@climar.kishou.go.jp

Headquarters
Marine Division, Global Environment and Marine Department, Japan Meteorological
Agency1-3-4, Otemachi, Chiyoda-ku, Tokyo 100 -8122, JAPAN
fax: +81-3-3211-6908, E-mail: vos@climar.kishou.go.jp

To maintain the accuracy of barometers for meteorological observations, they should bechecked every six months. If it is not possible for a ship to visit any of the above Japanese ports
for a long time, barometers may be checked as follows:1) Visit any foreign port in which a PMO is stationed to receive PMO service regardless offlag.
2) In Japanese ports other than above, barometers may be checked using email or facsimile.
Please contact any Japanese PMO for details.

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72

*(1

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Appendix 1
List of supplies for ship weather observations and reports*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS
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*(1JMA provides VOSs with the following materials free of charge:

Guide and tables for weather observation
Guide to Weather Observations for Ships
Guide to Ships’ Weather Reports
Ships' Weather Code Card
Table for Finding the Dew-point
JMA Cloud Plate
Beaufort Scale of Wind ForceMaterials for making weather observation reports
OBSJMA (Software on CD-ROM) and writeable disks for data storage
OBSJMA Operation Manual
Ship’s Weather Observation Field Note for OBSJMA
Marine Meteorological Logbook
Envelope to send logbooks, floppy disks or CD-Rs (postage free within Japan)

Brochures
Marine Meteorological Observations and Port Meteorological Services
Marine Meteorological Information Services for Shipping and Fishing

Bulletin
The Ship and Maritime Meteorology

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Contact
Marine Division
Global Environment and Marine Department
Japan Meteorological Agency (JMA)
1-3-4, Otemachi, Chiyoda-ku, Tokyo 100-8122 Japan
Facsimile No. +81 3 3211 6908
E-mail vos@climar.kishou.go.jp*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS$２

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*(1

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Appendix 2
Table for saturated vapor pressure*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1
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Table for saturated vapor pressure of water
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



























 
 


*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

A4

*(1

Table for saturated vapor pressure of supercooling water

㸦Υ㸧





















































ΥRIWHPSHUDWXUH



K3DK3DK3DK3DK3D
K3DK3DK3DK3DK3D







































































































*XLGHOLQHRIRFHDQREVHUYDWLRQV 9RO&KDS 7RVKL\D1$.$12 *(1

A5

*(1

Table for saturated vapor pressure of ice

㸦Υ㸧





















































ΥRIWHPSHUDWXUH



K3DK3DK3DK3DK3D
K3DK3DK3DK3DK3D



















































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Sea ice○Takenobu Toyota (Hokkaido University)

1. Introduction
Sea ice is any form of ice floating at sea which has originated from the freezing of seawater. Ice
found at sea may also contain ice of land origin, such as icebergs, lake ice which has formed on a lake,
and river ice which has formed on a river. All these kinds of ice floating in water are called floatingice. Almost all the floating ice found in the vicinity of Japan is sea ice. The ice existing in the sea ice
area is divided into fast ice (which is attached to the shore or an ice wall) and the remaining drift ice.
Since sea ice reflects a higher fraction of solar radiation than the surrounding seawater andsignificantly reduces the exchange of heat and materials between the atmosphere and ocean, it plays
an important role in shaping the polar climate. Therefore, the long-term standardized observation ofsea ice provides important information on climate change in polar regions.
Sea ice observations can be conducted from the seashore on land, navigating ships, aircrafts, orsatellite remote sensing. In this chapter we will describe the method and style of ship-based
observations, focusing on the internationally standardized ship-based visual observation in section 5-2.
The description includes an observation protocol designed for the Antarctic sea ice in sections 5-2-2
and 5-2-3, and one for Arctic sea ice in section 5-2-4. Nowadays, the data observed according to these
protocols in various sea ice regions on the earth are being archived in Australia. Some results
obtained from this observation method will be shown in section 5-2-5. In addition, visualobservations from the seashore observatories on land have been continued for more than a century,and this dataset provides an important baseline for studies of climate change. Therefore, we also
describe the present style of observation conducted by meteorological observatories by citing theobservation guidelines of the Japan Meteorological Agency in section 5-3.
The classification of sea ice used in the standardized observation protocol is based on the sea ice
nomenclature published by the World Meteorological Organization (WMO) in 1970 (revised in 2014).
Therefore, all the nomenclature of WMO will be listed in section 5-4.
2. Ship based observation
2-1 General description

The ship-based sea ice observation is conducted from the ship by observers with a goodknowledge of sea ice nomenclature, at fixed time intervals, to record the ice conditions around theship while the ship is navigating in the sea ice area. Ice conditions such as ice concentration, floe size,
and thicknesses of sea ice and snow are recorded according to the internationally standardized
observation protocol. These data not only contribute to the safe navigation by providing an overview
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G705ENr1-2of the ice conditions along the ship, but also can be used as a validation tool for satellite remotesensing data. Besides, the statistics of the observational records for a long-term period provides useful
information both for the intercomparison of the ice conditions between different sea ice regions andas a basic dataset of climate change.
For Antarctic sea ice, the standardized ship-based observation protocol was defined by the
ASPeCt (Antarctic Sea Ice Processes and Climate) program established by SCAR (ScientificCommittee on Antarctic Research) in 1997 (http://aspect.antarctica.gov.au/). One of the important
purposes of this program is to compile past records of the ice conditions observed in different formats
in various Antarctic sea ice regions as well as to provide a guideline for ship-based ice observation.
The observation protocol is based on the sea ice nomenclature published in 1970 (revised in 2014) by
WMO (World Meteorological Organization) (see section 5-4), and requires the observers to record
the ice thickness, floe size, surface topography, and the type and thickness of snow for the individual
ice types classified. The observation manual is described by Worby and Allison (1999), and therelevant part of this manual which is essential to the observation is cited here in sections 5-2-2 and
5-2-3.
In this protocol, much attention is paid to the estimation of mean ice thickness including ridged
ice. The observer is basically required to observe the thickness for level ice, and the thickness ofridged ice is estimated with the level ice thickness and the areal fraction and sail height of the ridge
using a simple ridge model. The mean ice thickness is calculated by areally-weighted thicknesses oflevel ice and ridged ice (section 5-2-3-3). Another way to apply the results to climate research is toestimate the integrated albedo of the total sea ice region containing various types of sea ice bysumming up the albedo prescribed for each ice type (section 5-2-3-4). Since first-year ice often takes
common features in form and arrangement irrespective of the regions, it is expected that thisobservation protocol is applicable in other seasonal ice zones as well as in the Southern Ocean. The
simplified version of the ASPeCt protocol for the Japanese Antarctic Research Expedition (JARE) is
proposed by Ohshima et al. (2006).
On the other hand, for Arctic sea ice, as may be expected with a longer history of sea ice
observation compared with Antarctic sea ice, ice conditions have been recorded in different formats
by different organizations so far. Therefore, it was not easy to set the internationally standardized
observation protocol (Worby and Eicken, 2009). However, recently with the rapid change of the ice
conditions in the Arctic Ocean, the expectation for establishing a network of the in-situ observationand the interest in standardizing the observation method have been increasing. Taking thisopportunity, the Climate and Cryosphere (CliC) Arctic Sea Ice Working Group was implemented in2008 under the auspices of the World Climate Research Programme (WCRP), and has been making
every effort to define an internationally standardized observation protocol for Arctic sea ice. While
this protocol is based on the ASPeCt protocol designed for Antarctic sea ice, some observation
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parameters are added to apply to Arctic sea ice.
The major differences between Arctic and Antarctic sea ice are the surface conditions during themelting season and the concentration of inclusions such as sediments and ice algae within sea ice. In
the Arctic, surface melting dominates (unlike the Antarctic sea ice), and a number of melt ponds
develop on the surface in the melting season. Since melt ponds evolve with time and affect thesurface heat budget significantly, additional codes are set for the observation of melt ponds.
Reflecting the fact that sea ice often grows on widespread shallow continental shelves in the Arctic
Ocean, it sometimes contains highly concentrated sediments. To record such conditions, observation
codes relevant to sediments are also added for Arctic sea ice. Another feature for the Arctic protocol
is that it includes observation items relevant to marine creatures. Refer to the Website(http://www.iarc.uaf.edu/ icewatch) for more details of the observation codes.
As supplemental information for ship-based sea ice observations, ship-borne electromagnetic
induction sounding has been used by many icebreakers to monitor the ice thickness distribution along
the ship track since the late 1990’s. This device is composed of transmitter and receiver coils, which
are set apart by a few meters, and is suspended at a distance of few meters from the ship during thenavigation to avoid the effect of the ship (Fig.5-1). The transmitter generates a primaryelectromagnetic field which induces eddy currents just below the ice bottom, because the conductivityof sea ice (0-50 mS m-1) is negligible compared to that of seawater (2500 mS m-1). In turn the induced
currents generate a secondary electromagnetic field. Then the distance to the ice bottom is calculated
from the strength of the secondary electromagnetic field sensed by the receiver coil. If we mount alaser profilometer on the instrument and measure the height of the instrument above the combinedsnow and ice surface, ice thickness can be obtained by subtracting it from the EM results. The meritof this method is that ice thickness data can be obtained irrespective of level ice or ridged ice.
Although the observational bias caused by taking the thinner route should sometimes be taken into
account, this method has allowed us to obtain the ice thickness distribution quantitatively in a wide
region while navigating. Refer to Haas (1998) and Uto et al. (2006) for details of this techniqueappliedtotheSouthern

Ocean

and

the

Sea

of

Okhotsk, respectively. If theice thickness monitoring by
this method is continued
along regular shipping routes,
it is expected that these data
will form a useful dataset formonitoring climate change.

Fig. 5-1. Schematic picture showing the EM sensor suspended fromthe German ice breaker “Polarstern” (cited from Haas (1998))

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2-2 Observational technique for Antarctic sea ice (cited from Worby and Allison (1999))(Remarks by the author are shown in Italics.)
A standard set of observations are made hourly by an observer on the ship’s bridge. These include
the ship’s position and total ice concentration, and an estimate of the areal coverage, thickness, floe
size, topography and snow cover of the three dominant ice thickness categories within a radius ofapproximately 1 km of the ship. The three dominant ice categories are defined as those with thegreatest areal concentration, and the thickest of these is defined as the primary ice type. There may betimes when only one or two different ice categories are present in which case only the primary, or
primary and secondary, classifications are defined. The observations are entered on log sheets using astandard set of codes based on the WMO (1970) nomenclature and designed exclusively for Antarctic
sea ice. A set of blank proformas is located in Table 5-1 and observation codes are shown in Table
5-2.
2-2-1 Ice Concentration (c)Total ice concentration is an estimate of the total area covered by all types of ice, expressed intenths, and entered as an integer between 0 and 10. In regions of very high ice concentration(95-99%) where only very small cracks are present, the recorded value should be 10 and the open
water classification should be 1 (small cracks). Regions of complete ice cover (100%) will be
distinguished by recording an open water classification of 0 (no openings). An estimate of theconcentration of each of the three dominant ice thickness categories is also made. These values arealso expressed in tenths and should sum to the value of the total ice concentration. It is sometimes
difficult to divide the pack into three distinct categories, and it may be necessary to group somecategories together to ensure their representation.
2-2-2 Ice Type (ty)The different ice categories, together with the codes used to record the observations, are shown in
Table 2.1. The ice categories are based on the [WMO, 1970] sea ice classifications. First year ice
greater than approximately 0.1 m thick is classified by its thickness (e.g., young grey ice 0.1-0.15 m;
first year ice 0.7-1.2 m), while thinner ice is generally classified by type (e.g., frazil, shuga, grease
and nilas). A single category is defined for multi-year ice. There is also a category for brash, which iscommon between floes in areas affected by swell and where pressure ridging has collapsed.
2-2-3 Ice Thickness (z)Ice thickness is estimated for each of the three dominant ice types. It is helpful to the observer tosuspend an inflatable buoy of known diameter (or other gauge) over the side of the ship,
approximately 1 m above the ice, to provide a scaled reference against which floe thickness can be
estimated. The ice thickness can then be determined quite accurately as floes turn sideways along the
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ship’s hull (Fig.5-2). Only the thickness of level floes, or the level ice between ridges, is estimated.
This is because ridges tend to break apart into
their component blocks when hit by the ship,
making it impossible to estimate their thickness.
In order to determine the thickness of ridged floes,
observations of the areal extent and mean sailheight of the ridges are made (see Section
5-2-2-5) and combined with the level ice
thickness data into a simple model (see Section
5-2-3-3).
Fig. 5-2. A sample of floes turning sideaways along
the ship’s hull.

Thinner, snow-free ice categories, which are particularly important for ocean- atmosphere heatexchange, can be reliably classified by a trained observer from their apparent albedo, while thethickness of very thick floes may be estimated by their freeboard. The accuracy of carefulobservations will be within 10-20% of the actual thickness, and a large sample of observations can be
expected to provide a good statistical description of the characteristics of the pack. This is particularly
true at the thin end of the thickness distribution where changes are most important for both radiantand turbulent heat transfer (e.g., Worby and Allison, 1991).
On dedicated scientific voyages, it is usually possible to make regular in situ measurements of ice
and snow thickness, both on level ice and across ridges, to “calibrate” the ship-based observations.
Worby et al. (1996) demonstrated a technique for combining in situ and ship-based observations toestimate the ice thickness distribution in the Bellingshausen Sea. Dedicated scientific voyages also
usually provide the opportunity to follow specific routes to optimise data quality, which may becompromised if the ship follows the most easily navigable routes. It is the observer’s responsibility toclearly indicate on the observation sheet when the ship is preferentially following leads so that thismay be considered during data processing.
2-2-4 Floe size (f)Floe size can be difficult to determine because it is not always clear where the boundary of a floe
is located. Cracks and leads delineate floe boundaries whereas ridges do not. Where smaller floes
have been cemented together to form larger floes, the larger dimension is recorded, but usually with acomment to indicate that smaller floes are visible. Where two floes have converged and ridged, thefloe size is taken as the combined size of the two. A good rule of thumb is : if you could walk frompoint A to point B, then both points are on the same floe. This guide can be helpful when trying to
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determine floe size. The length of the ship (about 100 m for most ice breakers) can act as a good
guide for estimating floe size. The ship’s radar can be useful for determining the size of very large
floes.
Floe size is recorded using a code between 100 and 700. New sheet ice (code 200) is normallyused for nilas. This code does not specify a floe size, but is a descriptor for refrozen leads andpolynyas. It is often used in conjunction with topography codes 100 (level ice) and 400 (finger
rafting).
2-2-5 Topography (t)As discussed above, the ice thickness estimates are only made of the level ice in a floe. This isbecause the thickness of ridges can not reliably be estimated from a ship, since they tend to break up
in to their component blocks when hit by the ship, rather than turning sideways so that their thickness
can be estimated. However, drilled transects across ridged ice floes indicate that the mass of ice inridges is a major contributor to the total ice mass of the pack, hence it is important to quantify theextent of ridging within the pack. To do this, the areal extent and mean sail height of ridges isrecorded for each ice type within the pack. The extent of surface ridging is estimated to the nearest
10%. It is important that observers not look too far from the ship when estimating the areal extent ofridges, otherwise only the ridge peaks are seen and not the level ice between them. This gives a false
impression of more heavily deformed ice than is actually present. The mean sail height is estimated to
the nearest half metre below 2 m, and to the nearest metre above 2 m. It is important to remember that
it is the mean sail height that is recorded. This can be difficult to estimate, particularly in flat lightwhen the sky is overcast. our experience has shown that ridge height is generally underestimated dueto the vertical perspective from the bridge.
Ridges are classified using a three digit code between 500 and 897. The first digit (5-8) is a
description of the type of ridge, which may be unconsolidated, consolidated or weathered. This isdetermined from the appearance of the ridge and is useful for estimating ridge sail density. The
second digit (0-9) describes the areal coverage of ridges, and the third digit (0-7) records the mean
sail height to the nearest 0.5 m. These observations are probably the most subjective of those madefrom the ship, and it is particularly important to standardise them between observers.
The observations of surface ridging are input to a model formulation as described in section 2-3-3,
to estimate the mass of ice in ridges.
2-2-6 Snow type (s)This is a descriptor for the state of the snow cover on sea ice floes. It is important for estimating
the area-averaged albedo of the pack as discussed in Section 5-2-3-4. The snow classification is an
integer between 0 and 10. For accurate surface albedo calculations, the snow cover classification
describes the surface snow. Hence, in a case where fresh snow has fallen over older wind-packed
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snow, the classification code should describe the freshly fallen snow cover. However, it is very
important that the total snow cover thickness is still recorded.
2-2-7 Snow thickness (sz)

An estimate of the snow cover thickness is made for each of the three dominant ice thickness
categories. Snow thickness is relatively straight forward to estimate for floes turned sideways along
the ship’s hull, although at times the ice/snow interface is difficult to distinguish, particularly when
the base of the snow layer has been flooded and snow-ice has formed.
2-2-8 Open water (o/w)

The codes for open water are descriptors for the size of the cracks or leads between floes, not aconcentration value (in tenths). As discussed above, the length and breadth of the ship can act as a
useful guide when estimating lead dimensions. The ship’s radar can also be useful, particularly atnight.
2-2-9 Meteorological Observations

Instantaneous conditions are usually recorded hourly, but this may be reduced to three hourly. The
standard set of observations include water temperature, air temperature, true wind speed and direction,
total cloud cover, visibility, and current weather. On most research vessels, water temperature, airtemperature and wind speed and direction will be displayed on the bridge, and may even be logged
for the duration of the voyage. Cloud cover can be estimated by the observer in eighths, and visibility
is estimated in kilometres from the ship. Wind speed is recorded in ms-1 and wind direction relative tonorth (◦T). The current weather is recorded using the Australian meteorological observer’s two digit
codes that are provided in Table 5-4.
2-2-10 Photographic Records

During daylight hours a photographic record of ice conditions can be kept. Slides are usuallytaken from the bridge at the time of each observation, and the log book has a column for recording
film and frame numbers. There is also scope for recording the frame number for a time lapse video
recorder which the authors have mounted on the ship’s rail. This captures a single video frame every
8 seconds, providing a comprehensive visual record of ice conditions on a single video tape for each
30 day period. This photographic archive is not generally used for quantitative analyses, but provides
an excellent reference that can be used in conjunction with the ship-based observations. At night thecamera is angled closer to the ship to view an area that can be adequately lit by flood lights mounted
on the ship’s rail.
*Note: Taking three photos at the fixed observation time from the bridge or the upper
bridge of the ship is recommended to record ice conditions, as shown in Fig.5-3.
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Fig. 5-3 Sample photos taken from the upper bridge of P/V “Soya”
in the southern Sea of Okhotsk（From left to right, portside, front, and starboard）

2-2-11 Comments

In addition to the hourly observations entered by code, there is scope for additional comments tobe recorded. These usually include a brief description of the characteristics of the pack, in particularfeatures which are not covered by the observation codes, such as frost flowers on dark nilas or swell
penetrating the pack. Brief details of sampling sites, buoy deployments or other ‘on ice’ activities
may also be recorded and, if necessary, a comment on how typical the ice along the ship’s route is of
the surrounding region.

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Table 5-1. An observation sheet for ASPeCt (1)Guideline of ocean observations Vol. 7 Chap. 5 Sea Ice© Takenobu TOYOTA 2018 G705ENr1:001-047

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Table 5-1. An observation sheet for ASPeCt (2)Guideline of ocean observations Vol. 7 Chap. 5 Sea Ice© Takenobu TOYOTA 2018 G705ENr1:001-047

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Table 5-2. Observation codes for ASPeCt

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2-3 Data entry and processing for Antarctic sea ice(cited from Worby and Allison (1999))2-3-1 Quality control

Checks are made to identify errors and inconsistencies in the data. These include, but are notlimited to:•snow thicker than ice•

thin ice types greater than 0.1 m thick•total concentration greater than 10/10, or not adding up to the sum of the concentrations of
the three dominant categories•

ice thickness categories not matching assigned thickness values•

topography or floe size codes incompatible with ice type (e.g., consolidated ridges onnilas)•

primary ice category thinner than secondary or tertiary categories•

distance between consecutive hourly observations greater than 20 km.

2-3-2 Editing data

The data set may be edited to exclude observations within a prescribed distance of the previous
observation. This is to prevent biasing in areas of heavy ice where the ship’s speed is reduced. The
distance is usually set to 6 nautical miles, corresponding to a straight line speed of 6 knots which mostice breakers are capable of maintaining in moderate pack ice. The processing software enables theuser to specify this distance, or to use all observations regardless of spacing.
Observations are also removed when there is obvious biasing caused by the ship following easily
navigable routes. The most common example of this is near the ice edge, when the ship may
constantly pick its way through leads. This is usually avoidable on voyages dedicated to sea ice
research, but may otherwise prove to be a problem. It is at the discretion of the observer to either notethat the data may be biased, or not record data under such circumstances.
2-3-3 Estimating the area-averaged ice and snow thicknesses

Estimates of the area-averaged ice and snow thicknesses may be made over the ice covered regionof the pack only, or for the total pack ice zone including the open water fraction. Each observation isequally weighted unless eliminated by the minimum distance rule described above. For each hourly
observation, the estimated ice thickness values for each of the three dominant ice thickness categories
are weighted by the ice concentration. This provides a mean thickness of the level ice within the pack.
To account for the mass of ice in ridges, the observations described in section 5-2-2-5 are used inconjunction with a simple model to calculate a corrected mean floe thickness (Zr). The model takes
the undeformed floe thickness (Zu), average sail height (S) and an estimate of the areal extent of
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surface ridging (R) as input parameters, and calculates the mean thickness of the floe (Zr), assuming a
triangular sail, isostasy and a ratio of ice and snow above sea level to ice below sea level as 5:1. The
assumption of a triangular sail cross section is consistent with the formulation of Hibler et al. (1974)
for calculating the effective thickness of ridged ice. Their formulation used a fixed slope angle of 26◦;
however the present study uses an implied variable slope angle which is dependent upon the areal
coverage of ridges and the average sail height. In this way broader ridges are flatter which isconsistent with the theory that ridges should build laterally once the limiting height is reached(Tucker and Govoni, 1981). The assumption of a triangular ridge is therefore not likely to induce
large errors. Published literature on sea ice density is sparse; however Buynitskiy (1967) presented
mean densities from East Antarctic sea ice for summer and winter ice of 875 kg m-3 and 920 kg m-3
respectively, and these are consistent with the value of 900 kg m-3 used in the model formulation. The
assumption of hydrostatic equilibrium must also hold on the large scale; however the effect of snow
drifts around ridges may induce errors in both the observations and the model. In particular, observers
may not be able to differentiate ridge sails from adjoining snow drifts, hence the observations of theareal coverage (and to a lesser extent, height) or ridging will include the fraction covered by snow.
This will affect the value r defined as the ratio of ice thickness below sea level to the combined
thickness of ice and snow above sea level. Hence, the assumption that ridge sails are solid ice with adensity of 900 kg m-3 is incorrect, and this is accounted for in the model.
To determine r in the vicinity of ridges, data from drilled thickness transects that intersectedridges were examined. Only transects, or parts thereof, with peaks in freeboard (the height of thesnow/ice interface above the sea level) >0.5 m were considered, and the mean ice and snow
thicknesses were calculated. A total of 339 drill holes from 9 thickness transects had mean ice andsnow thicknesses of 1.18 m and 0.16 m respectively. By assuming densities of 900 kg m-3 and 360 kg
m-3 for ice and snow respectively the mean draft was calculated to be 1.12 m. Hence, r = 5 in areas ofridged ice. The snow density value was derived from data collected on two voyages to the East
Antarctic pack (V9 92/93 and V1 95/96), with a mean value of 360 ± 110 kg m-3 over the range
120-760 kg m-3.
In order to calculate only the thickness of ice in ridges it is necessary to remove the snow from thecalculation. The ratio of ice below sea level : ice above, r’, is defined as :r’ = [1-(0.16/1.18)] r = 4.3
based on the mean ice and snow thickness given above. The value r’ = 4.3 compares well with thevalue of 4 used by Dierking (1995), which was based on drilled transect measurements by Lange andEicken (1991) and Wadhams et al. (1987).
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The model formulation to calculate the average thickness of ridged floes (Zr) can now be written
as :Zr = (r’ + 1)(0.5RS) + Zu
where R is the areal extent of surface ridging, S is the average sail height of ridges, and Zu is the
thickness of level (undeformed) ice in the floe (Fig.5-4).

Fig. 5-4 A simple ridge model for estimating the thickness of ridged ice

2-3-4 Calculating area-averaged albedo

The area-averaged albedo is computed from the ice concentration and allwave albedo for each ice
type. The allwave albedo values for different ice and snow thickness categories were originally takenfrom Allison et al. (1993); however these have recently been updated (Brandt et al., 2005; Table 5-3).
The average albedo is calculated over the entire pack, including the open water fraction. A value iscalculated at each hourly observation site, from which zonal averages may also be calculated.

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Table 5-3. Representative all-wave solar albedos of surface types in the East Antarctic sea ice zone inspring and summer. Values in bold are derived from measurements; all others were estimates by interpolation or
extrapolation. SON: September to November, DJF: December to February.
(cited from Brandt et al. (2005))

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2-4 Observational technique for Arctic sea ice

Arctic sea ice observations are normally conducted at hourly intervals from the ship’s bridge, aswith Antarctic sea ice. The standardization of the ship-based sea ice observation protocol for Arctic
sea ice is now being made by the Arctic Ice Watch program, with the aim to establish a PC software
called ASSIST (Arctic Shipborne Sea Ice Standardization Tool) for operational management. Since
the observation protocol is based on ASPeCt, the observations added for Arctic sea ice are listed here.
(For details, refer to http://www.iarc.uaf.edu/icewatch/assist)*Melt pond (Puddle)
Melt pond concentration

tenthsMelt pond pattern

1. linked 2. discrete
1. Frozen (dry or wet snow)

Melt pond surface type

2. Open
3. Bottom up

Melt pond freeboard

centimeters

Melt pond depth

centimeters
1. Solid

Melt pond bottom type

2. Some have thaw holes
3. All have thaw holes

Melt dried ice

logicalMelt rotten ice

logical*Ice algae and Sediments
Algae concentration

0. 0 1. <30 2. <60 3. >60%

Algae density-1. Not visible

Algae location

0. Trace

1. Light

2. Medium3. Strong

10. Top

20. Middle

30. bottom
Sediment concentration

0. 0 1. <30 2. <60 3. >60%

# As for algae concentration, select from the color menu below:

Additional observation items include the type and amount of cloud for upper, medium, and low
cloud. The observation codes are listed in Table 5-4.
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Table 5-4. Observation codes for ASSIST

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2-5 Some achievements

In this section, some results obtained from the ASPeCt protocol will be shown. One of the mostimportant achievements is that this method was the first to reveal a circumpolar map of ice thickness
distribution around the Antarctica. Worby et al. (2008) showed the mean annual ice thickness
distribution (including ridged ice) for the whole Antarctic region, from a compilation of 21,710
individual ship-based observations collected from 81 voyages to Antarctica for the period of 1981 to
2005, following the ASPeCt protocol (Fig.5-5). This figure clearly shows that the sea ice near the
Antarctic Peninsula in the western Weddell Sea and around the coastal area of the eastern Ross Sea iscomparatively thicker, and the maximum thickness exceeds 2 m in these regions. In other regions, ice
thickness is about 0.3-0.5 m in the marginal ice zone and about 1 m near the coast. These
characteristics almost coincide with the results predicted with numerical sea ice models (e.g.
Timmermann et al., 2002), providing a valuable ground truth data. However, the observational dataand period still does not appear to be sufficient to analyze the interannual variability of ice conditionsin the Southern Ocean. For discussion of climate change, further continuous observations are strongly
encouraged.
On the other hand, in the southern Sea of Okhotsk, cooperative sea ice observations have been
conducted by Hokkaido University and the Japan Coast Guard onboard P/V “Soya” in February every
winter since 1996. In particular, after 2001, the ship-based visual observation has been conductedaccording to the ASPeCt protocol (Toyota et al., 2007). Since the Sea of Okhotsk is a seasonal sea icezone like most of the Southern Ocean, and since the sea ice there has many common properties with
the Antarctic sea ice, the ASPeCt protocol is considered to be useful to obtain the properties of the ice
conditions there. Fig. 5-6 shows the histograms of floe size and thickness obtained by compiling 546
ship-based observations collected in the southern Sea of Okhotsk for the period of 2001 to 2015. It isfound from this figure that the dominant floe size category is ice cake (2 m to 20 m) and nilas eventhough vast floes which comprise a few percents of the floe size distribution. The dominant thickness
category is thin first-year ice (30 cm to 70 cm) and nilas, which contrasts to the result obtained along
the ship track of JARE off East Antarctica (Ohshima et al., 2006) where a small floe (20 m to 100 m)
and medium first-year ice (70 cm to 120 cm) are dominant. The mean ice thicknesses of level ice,ridged ice, and total ice floes are estimated to be 0.29 m, 1.58 m, and 0.63 m, which is somewhat
thinner than those of winter Antarctic sea ice (level ice: 0.38 – 0.49 m, total thickness: 0.54 – 0.72 m;
Worby et al., 2008).
Thus standardized ship-based observations are not only useful to find the properties of the ice
conditions in the individual sea ice area, but they also enable us to compare properties between
different ice areas. One of the advantages seems to be the feasibility at only a small cost. It is hopedthat the continuity of ship-based observations will contribute to the understanding of climate change.
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Fig. 5-5 Circumpolar map of mean annual ice thickness distribution, including ridged ice,
obtained by compiling ASPeCt data on 2.5o lat×5.0o lon grid (cited from Worby et al., 2008).

60

(%)

(a) Floe size(b) Ice thickness

(%)

60
40

40

20

20

0

F P N B R1 R2 R3 R4 R50

NewNls P H1 H2 H3 H4 H5 B

Fig. 5-6 Mean histograms obtained from ASPeCt observations conducted in the southern Sea of
Okhotskfor the period of 2001 to 2015 for(a) floe size（F: Frazil ice, P: Pancake ice, N: Nilas, B: Brash ice, R1: 2-20m, R2: 20-100m,
R3: 100-500m, R4: 500m-2km, R5: >2km）(b) thickness category（New: New ice, Nls: Nilas, P: Pancake ice, B: Brash ice, H1: 10-15cm,
H2: 15-30cm, H3: 30-70cm, H4: 70-120cm, H5: >120cm）

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3. Coastal observation#(#Translation of “Guideline for oceanographical observations” published by the Japan
Meteorological Agency in 2004)
Coastal sea ice observations are conducted by observers with a good knowledge of sea ice
nomenclature at a fixed time of the day at a fixed coastal site. By transmitting the observed ice
conditions immediately via a telecommunications network, the data can be used for disasterprevention (e.g., safe ship navigation) as well as ground truth data for sea ice observations conductedby satellite remote sensing. Furthermore, the long-term collection of sea ice observations serves asimportant baseline dataset for the monitoring of climate.
3-1 Observation site

The observation site should be a relatively high place such as the roof of a building so thatobservers can view a wide area including the coastline and large sea of the sea surface.

3-2 Observation parameters

Observation parameters include total ice amount, ice conditions around the coastal region, and thefirst and last dates of sea ice coverage.
3-3 Observation time

Coastal observations are conducted at 09:00 am (LST). If the first or last sea ice phenomena areobserved at another time, the observation time should be recorded in the column for remarks on theobservation sheet.
3-4 Observation period

In principle, the observation period is from the date when sea ice first appears in sight until thedate when sea ice disappears completely out of sight.
3-5 Observation of total ice amount

Ice amount is defined as the areal fraction covered with all types of sea ice within the observation
area. Ice amount is classified into true ice amount, defined as the fraction of real sea ice area to thereal total observation area, and apparent ice amount defined as the fraction of apparent sea ice area
seen from the slant view to the apparent total observation area. Observers observe the apparent ice
amount, and record the total ice amount, which is defined as the apparent ice amount for the whole
sea surface in sight (including the port area), at the fixed observation time.
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Ice amount is recorded according to the grade shown in Table 5-5. This expression is analogous to
the total cloud amount (in tenths) in surface meteorological observations. Ice amount is determinedsolely by the area covered with sea ice, independent of ice types. Some matters which require more
attention are listed below:
1. As for the sea ice near the horizon, observers should avoid unreasonable judgments anddetermine ice amount simply from the appearance because the precise conditions such as aspace between floes are often hard to see.
2. Observers should take care to notice relatively dark new sheet ice when present.
3. When only part of the sea surface can be seen due to bad visibility caused by blowing snow orfog, ice amount should be observed within the visible range. In this case, observers should
write down the data in parenthesis and put remarks about the reason for the bad visibility inthe observation sheet.

Table 5-5 Grade of total ice amount

Code

Ice

Fraction of sea ice to the total sea surface in sightamount00

No sea ice

10+

Sea ice is present in sight but the fraction is < 10%.

1

1

Sea ice occupies 10% of the total sea surface in sight.

2

2

Sea ice occupies 20% of the total sea surface in sight.

2

3

Sea ice occupies 30% of the total sea surface in sight.

3

4

Sea ice occupies 40% of the total sea surface in sight.

4

5

Sea ice occupies 50% of the total sea surface in sight.

5

6

Sea ice occupies 60% of the total sea surface in sight.

6

7

Sea ice occupies 70% of the total sea surface in sight.

6

8

Sea ice occupies 80% of the total sea surface in sight.

7

9

Sea ice occupies 90% of the total sea surface in sight.

7

10-

Total sea surface in sight is mostly covered with sea ice
except for small open area.

8

10

The sea surface is covered completely with sea ice.

//

Unknown

3-6 Observation of ice conditions around the coastline

Ice conditions around the coastline are observed, to report the presence of fast ice or drift ice, andGuideline of ocean observations Vol. 7 Chap. 5 Sea Ice© Takenobu TOYOTA 2018 G705ENr1:001-047

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the state of open water such as fractures, leads, and whatever in the sea ice area. The observed data
are recorded with the 11 grades listed in Table 5-6, according to the format of coastal sea ice
observation report: JM305.
Although in general sea ice is classified into fast ice and drift ice, it is hard to judge theclassification in some cases. Since this matter is relevant to the definition of the first and last dates ofsea ice phenomena, however, some standardization is required.
Fast ice is defined by the sea ice which forms and remains fast along the coast, where it is
attached to the shore. Fast ice may be formed in situ from sea water or by freezing of pack ice of any
age to the shore.
On the other hand, drift ice is the term used in a wide sense to include any area of sea ice, otherthan fast ice, no matter what form it takes. Therefore, drift ice includes not only sea ice which has
been advected from the northern or central Sea of Okhotsk, far away from the observation site along
the Hokkaido coast, but also new ice which has formed off shore, and also sea ice which was onceoriginated from fast ice but is now drifting after becoming detached from the shore. Although thejudgment between fast ice and drift ice is often difficult from coastal observation, sea ice extending
from the shore should be recorded as fast ice even if coastal leads covered with new sheet ice mayintervene between the shore and the off-shore ice. In the case where the sea ice is not contiguous withthe coast, it should be recorded as drift ice.
The most important thing in the coastal sea ice observation is the judgment of the presence ofcoastal leads, or whether drift ice is attached to the shore. While it is relatively easy to discriminate
fast ice from drift ice at the beginning of the ice season, the judgment becomes difficult when drift ice
gets stuck after becoming attached to the shore or when leads form offshore after becoming attachedto the shore. In such cases, the offshore ice should be recorded as drift ice though the origin is
unknown. However, sea ice which is grounded on the shore or remaining in the port after the ice packretreats should be recorded as fast ice, not drift ice.

Table 5-6

Ice conditions along the coast (Report format: JM305）

Report code

Ice condition along the coast0

No sea ice

1

Drift ice on the horizon.

2

Fast ice around the shore, while drift ice offshore separated by leads.

3

Leads along the shore and drift ice offshore.

4

Drift ice along the shore and no ice offshore.

5

Drift ice along the shore and another drift ice offshore separated by leads.

6

Drift ice attached to fast ice along the shore.
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7

Drift ice mostly covering all the sea surface in sight.

8

Drift ice mostly approaching the port.

9

Drift ice entering the inside of the port.

/

Unknown

Remarks(1) If more than two codes are fitting, the larger number should be selected.
(2) Ice conditions are independent of ice amount and concentration. However, note thatcode 7 should be used for ice amount greater than 9.

3-7 Observation of the first and last dates of sea ice coverage

The observation of the first and last dates indicates the duration of ice coverage for the year. The
definitions of the first and last dates of sea ice phenomena are as follows:
1. The first date of drift ice in sightThis is defined by the date when drift ice advected from offshore beyond the observation area first
appears in sight in the ice season. This observation is not for when sea ice first forms in theobservation area, or the first formation of fast ice.
2. The last date of drift ice in sightThis is defined by the last date when drift ice is found in sight within the observation area. Drift
ice which remains offshore after the retreat of the ice pack should be taken into account, irrespectiveof ice amount. A small amount of ice floes remaining around the port or near the coast should be
excluded.
3. The first date of drift ice attached to the shore
This is defined by the date when drift ice first becomes attached to the shore in the ice season,
resulting in the closure of coastal lead for the ship navigation.
4. The first date of reopening of the coastal lead (“Umiake” in Japanese)
This is defined by the date when reopening of the sea along the coast allows a ship navigation
along the shore, with total ice amount less than 5. In the case when drift ice gets attached to the shore
again after the first formation of coastal lead and this state continues for more than 3 days, the next
reopening date should be recorded as “Umiake”. In the case when the short-term (< 2 days)
attachments of drift ice to the shore are repeated and the interval between attachments is less than 15days, the reopening date after the final attachment period should be recorded as “Umiake”. On theother hand, in the case where there is no opening along the shore even if total ice amount is less than
5, the date should not be recorded as “Umiake”.
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Since the sight range and the distance to the horizon are determined by the observation height, theobservational results about the first and last dates of sea ice phenomena should not be recorded except
when the observation is conducted at a fixed site. Furthermore, to determine the last date, theobservation should be continued for several days even after sea ice coverage appears to end because
sea ice coverage may occur again later in the ice season. Particularly when the last date is earlier thannormal, monitoring should be continued until around the normal date.
3-8 Monthly observation sheet

In the monthly observation sheet, the following matters should be filled in, compiled and archived
as the original data sources. A sample of the records is shown in Table 5-7. In the case where there isno sea ice, total ice amount should be recorded as “0” and the ice conditions as “-“.
1. Total ice amount is filled in according to the grades in Table 5-5. In the case of bad visibility,
apparent ice amount should be filled in with parenthesis. When observation is difficult, “×” should be
filled in.
2. The coastal ice condition section is filled in according to the transmitting codes listed in Table
5-6 (JM305). When observation is difficult due to bad visibility or other reasons, “×” should be filledin.
3. Remarks should be written when the first date of drift ice in sight or drift ice attached to theshore is observed or in the case where total ice amount is recorded as “×” or in parentheses.
4. The first and last dates of sea ice phenomena and the difference from the dates of the normal
year and the previous year should be filled in.
5. General conditions are described briefly about the sea ice conditions during the month. In
addition, when disasters related to sea ice have occurred, these should be described in the observation
sheet.

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Table 5-7. Monthly observation sheet for coastal sea ice observation

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4. Sea ice nomenclature (cited from WMO (2014))
WMO SEA-ICE NOMENCLANTURETERMINOLOGY – VOLUME I
WMO/OMM/ВМО - No.259 • Edition 1970 – 2014 note:English only
4-1. FLOATING ICE
Any form of ice found floating in water. The principal kinds of floating ice are lake ice, river ice, andsea ice which form by the freezing of water at the surface, and glacier ice (ice of land origin) formed onland or in an ice shelf. The concept includes ice that is stranded or grounded.
Sea ice:
Any form of ice found at sea which has originated from the freezing of sea water.
Fast ice:
Sea ice which forms and remains fast along the coast, where it is attached to the shore, to an ice
wall, to an ice front, between shoals or grounded icebergs. Vertical fluctuations may be observed
during changes of sea-level. Fast ice may be formed in situ from sea water or by freezing offloating ice of any age to the shore, and it may extend a few metres or several hundred kilometresfrom the coast. Fast ice may be more than one year old and may then be prefixed with theappropriate age category (old, second-year, or multi-year). If it is thicker than about 2 m above
sea-level it is called an ice shelf.
Drift ice / pack ice:
Term used in a wide sense to include any area of sea ice other than fast ice no matter what form ittakes or how it is disposed. When concentrations are high, i.e. 7/10 or more, drift ice may bereplaced by the term pack ice*.
*Note: Previously the term pack ice was used for all ranges of concentration.
Ice of land origin:
Ice formed on land or in an ice shelf, found floating in water. The concept includes ice that is stranded
or grounded.
Lake ice:
Ice formed on a lake, regardless of observed location.
River ice:
Ice formed on a river, regardless of observed location.

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4-2. DEVELOPMENT
New ice:
A general term for recently formed ice which includes frazil ice, grease ice, slush and shuga. Thesetypes of ice are composed of ice crystals which are only weakly frozen together (if at all) and have adefinite form only while they are afloat.
Frazil ice:
Fine spicules or plates of ice, suspended in water.
Grease ice:
A later stage of freezing than frazil ice when the crystals have coagulated to form a soupy layer on
the surface. Grease ice reflects little light, giving the sea a matt appearance.
Slush:Snow which is saturated and mixed with water on land or ice surfaces, or as a viscous floating massin water after a heavy snowfall.
Shuga:
An accumulation of spongy white ice lumps, a few centimetres across; they are formed from grease
ice or slush and sometimes from anchor ice rising to the surface.
Nilas:
A thin elastic crust of ice, easily bending on waves and swell and under pressure, thrusting in a patternof interlocking “fingers” (finger rafting). Has a matt surface and is up to 10 cm in thickness. May be
subdivided into dark nilas and light nilas.
Dark nilas: Nilas which is under 5 cm in thickness and is very dark in colour.
Light nilas:
Nilas which is more than 5 cm in thickness and rather lighter in colour than dark nilas.
Ice rind:A brittle shiny crust of ice formed on a quiet surface by direct freezing or from grease ice, usuallyin water of low salinity. Thickness to about 5 cm. Easily broken by wind or swell, commonly
breaking in rectangular pieces.
Pancake ice:
Predominantly circular pieces of ice from 30 cm - 3 m in diameter, and up to about 10 cm inthickness, with raised rims due to the pieces striking against one another. It may be formed on a slightswell from grease ice, shuga or slush or as a result of the breaking of ice rind, nilas or, under severe
conditions of swell or waves, of grey ice. It also sometimes forms at some depth at an interface
between water bodies of different physical characteristics, from where it floats to the surface; its
appearance may rapidly cover wide areas of water.
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Young ice:
Ice in the transition stage between nilas and first-year ice, 10-30 cm in thickness. May be subdivided
into grey ice and grey-white ice.
Grey ice:
Young ice 10-15 cm thick. Less elastic than nilas and breaks on swell. Usually rafts under pressure.
Grey-white ice:
Young ice 15-30 cm thick. Under pressure more likely to ridge than to raft.
First-year ice:
Sea ice of not more than one winter’s growth, developing from young ice; thickness 30 cm – 2 m.
May be subdivided into thin first-year ice / white ice, medium first-year ice and thick first-year ice.
Thin first-year ice / white ice: First-year ice 30-70 cm thick.
Thin first-year ice / white ice first stage: 30-50 cm thick.
Thin first-year ice / white ice second stage: 50-70 cm thick.
Medium first-year ice: First-year ice 70-120 cm thick.
Thick first-year ice: First-year ice over 120 cm thick.
Old ice:
Sea ice which has survived at least one summer’s melt; typical thickness up to 3m or more. Most
topographic features are smoother than on first-year ice. May be subdivided into residual,
second-year ice and multi-year ice.
Residual ice:
First-year ice that has survived the summer’s melt and is now in the new cycle of growth. It is 30 to
180 cm thick depending on the region where it was in summer. After 1 January (in the Southernhemisphere after 1 July), this ice is called second-year ice.
Second-year ice:
Old ice which has survived only one summer’s melt; typical thickness up to 2.5 m and sometimes
more. Because it is thicker than first-year ice, it stands higher out of the water. In contrast to
multi-year ice, summer melting produces a regular pattern of numerous small puddles. Bare patches
and puddles are usually greenish-blue.
Multi-year ice:
Old ice up to 3 m or more thick which has survived at least two summers’ melt. Hummocks evensmoother than in second-year ice, and the ice is almost salt-free. Colour, where bare, is usually blue.
Melt pattern consists of large interconnecting irregular puddles and a well-developed drainage
system.
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Development of lake ice:
Because of the absence of salt in the water, the freezing and growth processes of lake ice areconsiderably different from those of sea ice. Generally, lake ice forms and is destroyed more quickly
than sea ice, is more brittle and harder than sea ice.
New lake ice: Recently formed lake ice less than 5 cm thick.
Thin lake ice: Lake ice that is 5-15 cm in thickness.
Medium lake ice: Lake ice that is 15-30 cm in thickness.
Thick lake ice: Lake ice that is 30-70 cm in thickness.
Very thick lake ice: Lake ice that is greater than 70 cm in thickness.
Snow Ice:
Ice formed by refreezing flooded snow creating an ice layer that bonds firmly to the top surface of afloe.

4-3. FORMS OF FAST ICE
Fast ice:
Sea ice which forms and remains fast along the coast, where it is attached to the shore, to an ice wall,
to an ice front, between shoals or grounded icebergs. Vertical fluctuations may be observed duringchanges of sea-level. Fast ice may be formed in situ from sea water or by freezing of floating ice of
any age to the shore, and it may extend a few metres or several hundred kilometres from the coast.
Fast ice may be more than one year old and may then be prefixed with the appropriate age category(old, second-year, or multi-year). If it is thicker than about 2 m above sea-level it is called an ice
shelf.
Young Coastal ice:
The initial stage of fast ice formation consisting of nilas or young ice, its width varying from a few
metres up to 100-200 m from the shoreline.
Icefoot:
A narrow fringe of ice attached to the coast, unmoved by tides and remaining after the fast ice has
moved away.
Anchor ice:
Submerged ice attached or anchored to the bottom, irrespective of the nature of its formation.

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Grounded ice:
Floating ice which is aground in shoal water.
Stranded ice:
Ice which has been floating and has been deposited on the shore by retreating high water.
Grounded Hummock:
Hummocked grounded ice formation. There are single grounded hummocks and lines (or chains) ofgrounded hummocks.

4-4. OCCURRENCE OF FLOATING ICE
Ice cover:
The ratio of an area of ice of any concentration to the total area of sea surface within some large
geographic local; this local may be global, hemispheric, or prescribed by a specific oceanographic
entity such as Baffin Bay or the Barents Sea.
Concentration:
The ratio expressed in tenths* describing the amount of the sea surface covered by ice as a fraction of
the whole area being considered. Total concentration includes all stages of development that arepresent, partial concentration may refer to the amount of a particular stage or of a particular form of
ice and represents only a part of the total.
*Note: In historical sea-ice data octas have been used by some countries.
Compact ice:
Floating ice in which the concentration is 10/10 and no water is visible.
Consolidated ice:
Floating ice in which the concentration is 10/10 and the floes are frozen together.
Very Close Ice:
Floating ice in which the concentration is 9/10 to less than 10/10.
Close ice:
Floating ice in which the concentration is 7/10 to 8/10, composed of floes mostly in contact.
Open ice:
Floating ice in which the ice concentration is 4/10 to 6/10, with many leads and polynyas, and thefloes are generally not in contact with one another.
Very open ice:
Floating ice in which the concentration is 1/10 to 3/10 and water preponderates over ice.

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Open water:
A large area of freely navigable water in which sea ice is present in concentrations less than 1/10.
No ice of land origin is present.
Bergy water:
An area of freely navigable water in which ice of land origin is present in concentrations less than
1/10. There may be sea ice present, although the total concentration of all ice shall not exceed
1/10.
Ice-free:No sea ice present. If ice of any kind is present this term should not be used.

Forms of floating ice
Pancake ice:
Predominantly circular pieces of ice from 30 cm – 3 m in diameter, and up to about 10 cm inthickness, with raised rims due to the pieces striking against one another. It may be formed on aslight swell from grease ice, shuga or slush or as a result of the breaking of ice rind, nilas or, under
severe conditions of swell or waves, of grey ice. It also sometimes forms at some depth, at aninterface between water bodies of different physical characteristics, from where it floats to thesurface; its appearance may rapidly cover wide areas or water.
Floe:
Any contiguous piece of sea ice. Floes are subdivided according to horizontal extent as follows:
Floe giant: Over 10 km across.
Floe vast: 2-10 km across.
Floe big: 500-2000 m across.
Floe medium: 100-500 m across.
Floe small: 20-100 m across.
Ice cake: Less than 20 m across.
Small ice cake: Less than 2 m across.
Cake ice:
Cake Ice is commonly used in Antarctica to refer to a collection of ice cakes. This should not be
confused with pancake ice. Cake ice is older and thicker than pancake ice.
Floeberg:
A massive piece of sea ice composed of a hummock, or a group of hummocks frozen together, andseparated from any ice surroundings. It may typically protrude up to 5 m above sea-level.
Floebit:A relatively small piece of sea ice, normally not more than 10 m across composed of (a)hummock(s) or part of (a) ridge(s) frozen together and separated from any surroundings. It
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typically protrudes up to 2 m above sea-level.
Ice breccia: Ice of different stages of development frozen together.
Brash ice:
Accumulations of floating ice made up of fragments not more than 2 m across, the wreckage ofother forms of ice.
Iceberg:
A massive piece of ice of greatly varying shape, protruding more than 5 m above sea-level, which
has broken away from a glacier, and which may be afloat or aground. Icebergs may be described astabular, dome-shaped, sloping, pinnacled, dry-docked, blocky, weathered or glacier bergs inaddition to having a size qualifier.
Glacier berg: An irregularly shaped iceberg
Tabular berg: A flat-topped iceberg. Most tabular bergs form by calving from an ice shelf andshow horizontal banding (cf. ice island).
Domed iceberg: An iceberg which is smooth and rounded on top.
Sloping iceberg: An iceberg which is rather flat on top and with steep vertical sides on one end,
sloping to lesser sides on the other end.
Pinnacled iceberg: An iceberg with a central spire or pyramid, with one or more spires.
Dry-docked iceberg: An iceberg which is eroded such that a U-shaped slot is formed near or atwater level, with twin columns or pinnacles. This is also referred to as a twinned iceberg.
Blocky iceberg: A flat-topped iceberg with steep vertical sides.
Weathered iceberg: An iceberg that shows marked signs of deterioration from the effects ofatmosphere and ocean.
Ice island: A large piece of floating ice protruding about 5 m above sea-level, which has broken
away from an Arctic ice shelf, having a thickness of 30-50 m and an area of from a few thousand
sq.m to 500 km² or more, and usually characterized by a regularly undulating surface which
gives it a ribbed appearance from the air.
Ice island Fragment: Piece of an ice island that has broken away from the main mass.
Very large iceberg: A piece of glacier ice extending more than 75 m above sea level and with alength of more than 200 m.
Large iceberg: A piece of glacier ice extending 46 to 75 m above sea level and with a length of
121 to 200 m.
Medium iceberg: A piece of glacier ice extending 16 to 45 m above sea level and with a length of
61 to 120 m.
Small iceberg: A piece of glacier ice extending 5 to 15 m above sea level and with a length of 15
to 60 m.

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Bergy bit: A large piece of floating glacier ice, generally showing less than 5 m above sea-level but
more than 1 m and normally about 100-300 m² in area.
Growler: Piece of ice smaller than a bergy bit and floating less than 1 m above the sea surface, agrowler generally appears white but sometimes transparent or blue-green in colour. Extending
less than 1 m above the sea surface and normally occupying an area of about 20 m², growlers are
difficult to distinguish when surrounded by sea ice or in high sea state.

Arrangement
Ice field: Area of floating ice consisting of any size of floes, which is greater than 10 km across(cf. patch).
Large ice field: An ice field over 20 km across.
Medium ice field: An ice field 15-20 km across.
Small ice field: An ice field 10-15 km across.
Ice patch: An area of floating ice less than 10 km across.
Ice massif: A variable accumulation of close or very close ice covering hundreds of square
kilometers which is found in the same region every summer.
Belt: A large feature of drift ice arrangement; longer than it is wide; from 1 km to more than 100 km
in width.
Tongue: A projection of the ice edge up to several kilometers in length, caused by wind or current.
Strip: Long narrow area of floating ice, about 1 km or less in width, usually composed of small
fragments detached from the main mass of ice, and run together under the influence of wind, swellor current.
Ice isthmus: A narrow connection between two ice areas of very close or compact ice. It may bedifficult to pass, whilst sometimes being part of a recommended route.
Bight: An extensive crescent-shaped indentation in the ice edge, formed by either wind or current.
Ice jam: An accumulation of broken river ice or sea ice not moving due to some physical restriction
and resisting to pressure.
Ice edge: The demarcation at any given time between the open sea and sea ice of any kind, whether
fast or drifting. It may be termed compacted or diffuse (cf. ice boundary).
Compacted ice edge: Close, clear-cut ice edge compacted by wind or current; usually on thewindward side of an area of drift ice.
Jammed brash barrier:
A strip or narrow belt of new, young or brash ice (usually 100-5000 m wide) formed at theedge of either drift or fast ice or at the shore. It is heavily compacted mostly due to wind action
and may extend 2 to 20 m below the surface but does not normally have appreciabletopography. Jammed brash barrier may disperse with changing winds but can also consolidate
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to form a strip of unusually thick ice in comparison with the surrounding drift ice. This is also
known as a windrow in the Baltic Sea.
Diffuse ice edge: Poorly defined ice edge limiting an area of dispersed ice; usually on the leeward
side of an area of drift ice.
Ice limit: Climatological term referring to the extreme minimum or extreme maximum extent of
the ice edge in any given month or period based on observations over a number of years. Termshould be preceded by minimum or maximum (cf. mean ice edge).
Mean ice edge: Average position of the ice edge in any given month or period based on
observations over a number of years. Other terms which may be used are mean maximum iceedge and mean minimum ice edge (cf. ice limit and median ice edge).
Median ice edge: Median (50% occurrence) position of the ice edge in any period based on a
sufficient number of observations (cf. ice limit and mean ice edge)
Fast-ice edge:
The demarcation at any given time between fast ice and open water.
Ice boundary: The demarcation at any given time between fast ice and drift ice or between areas ofdrift ice of different concentrations (cf. ice edge).
Fast ice boundary:
The ice boundary at any given time between fast ice and drift ice.
Concentration boundary:A line approximating the transition between two areas of drift ice with distinctly different
concentrations.
Iceberg tongue: A major accumulation of icebergs projecting from the coast, held in place bygrounding and joined together by fast ice.
Marginal Ice Zone: The region of an ice cover which is affected by waves and swell penetrating into
the ice from the open ocean.

4-5. FLOATING-ICE MOTION PROCESSESDiverging:Ice fields or floes in an area are subjected to diverging or dispersive motion, thus reducing ice
concentration and/or relieving stresses in the ice.
Compacting:Pieces of floating ice are said to be compacting when they are subjected to a converging motion,
which increases ice concentration and/or produces stresses which may result in ice deformation.
Shearing:
An area of drift ice is subject to shear when the ice motion varies significantly in the direction normal
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to the motion, subjecting the ice to rotational forces. These forces may result in phenomena similar toa flaw (q.v.).

4-6. DEFORMATION PROCESSES
Fracturing:
Pressure process whereby ice is permanently deformed, and rupture occurs. Most commonly used todescribe breaking across very close ice, compact ice and consolidated ice.
Hummocking:The pressure process by which sea ice is forced into hummocks. When the floes rotate in the process it
is termed screwing.
Ridging:
The pressure process by which sea ice is forced into ridges.
Rafting:
Pressure processes whereby one piece of ice overrides another. Most common in new and young ice(cf. finger rafting).
Finger rafting: Type of rafting whereby interlocking thrusts are formed like “fingers” alternately overand under the other. This is commonly found in nilas and in grey ice. (It was noted that finger
rafting in grey ice is common in Antarctica).
Shore ice ride-up: A process by which ice is pushed ashore as a slab.
Weathering:
Processes of ablation and accumulation which gradually eliminate irregularities in an ice surface.

4-7. OPENINGS IN THE ICE
Fracture:
Any break or rupture through very close ice, compact ice, consolidated ice, fast ice, or a single floe
resulting from deformation processes. Fractures may contain brash ice and/or be covered with nilas
and/or young ice. Length may vary from a few meters to many kilometers.
Crack: Any fracture of fast ice, consolidated ice or a single floe which may have been followed byseparation ranging from a few centimeters to 1 m.
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Tide crack: Crack at the line of junction between an immovable ice foot or ice wall and fast ice,the latter subject to rise and fall of the tide.
Flaw: A narrow separation zone between drift ice and fast ice, where the pieces of ice are inchaotic state; it forms when drift ice shears under the effect of a strong wind or current along thefast ice boundary (cf. shearing).
Very small fracture: 1 to 50 m wide.
Small fracture: 50 to 200 m wide.
Medium fracture: 200 to 500 m wide.
Large fracture: More than 500 m wide.
Fracture zone:
An area which has a great number of fractures.
Fractures concentration: Degree of disunity in an ice area.
Lead:
Any fracture or passage-way through sea ice which is navigable by surface vessels.
Shore lead:
A lead between drift ice and the shore or between drift ice and an ice front.
Flaw lead:
A passage-way between drift ice and fast ice which is navigable by surface vessels.
Polynya:
Any non-linear shaped opening enclosed in ice. Polynyas may contain brash ice and/or be covered
with new ice, nilas or young ice.
Shore polynya:
A polynya between drift ice and the coast or between drift ice and an ice front.
Flaw polynya: A polynya between drift ice and fast ice.
Recurring polynya: A polynya, which recurs in the same position every year.

4-8. ICE-SURFACE FEATURES
Level ice: Sea ice which has not been affected by deformation.
Deformed ice:
A general term for ice which has been squeezed together and in places forced upwards (anddownwards). Subdivisions are rafted ice, ridged ice and hummocked ice.
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Rafted ice:
Type of deformed ice formed by one piece of ice overriding another (cf. finger rafting).
Ice rafting concentration:
Concentration (aerial coverage) of ice rafting in an ice area in tenths.
Finger rafted ice:
Type of rafted ice in which floes thrust 'fingers' alternately over and under the other.
Ridge:
A line or wall of broken ice forced up by pressure. May be fresh or weathered. The submerged
volume of broken ice under a ridge, forced downwards by pressure, is termed an ice keel.
New ridge:
Ridge newly formed with sharp peaks and slope of sides usually 40°. Fragments are visible fromthe air at low altitude.
Weathered ridge:
Ridge with peaks slightly rounded and slope of sides usually 30o to 40o.
Individual fragments are not discernible.
Very weathered ridge:
Ridge with tops very rounded, slope of sides usually 20o-30o.
Aged ridge:
Ridge which has undergone considerable weathering. These ridges are best described as
undulations.
Consolidated ridge: A ridge in which the base has frozen together.
Ridged ice:
Ice piled haphazardly one piece over another in the form of ridges or walls. Usually found in
first-year ice (cf. ridging).
Ridged ice zone:
An area in which much ridged ice with similar characteristics has formed.
Shear ridge:
An ice ridge formation which develops when one ice feature is grinding past another. This type ofridge is more linear than those caused by pressure alone.
Shear ridge field: Many shear ridges side by side.
Hummock:A hillock of broken ice which has been forced upwards by pressure. May be fresh or weathered. The
submerged volume of broken ice under the hummock, forced downwards by pressure, is termed abummock.
Ice ridge concentration:
Concentration (aerial coverage) of hummocked ice of all kinds in an ice area in tenths. Up to three
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values may be given to correspond to the partial concentrations.
Hummocked ice:
Sea ice piled haphazardly one piece over another to form an uneven surface. When weathered, has
the appearance of smooth hillocks.
Rubble field:
An area of extremely deformed sea ice of unusual thickness formed during the winter by the
motion of drift ice against, or around a protruding rock, islet or other obstruction.
Standing floe: A separate floe standing vertically or inclined and enclosed by rather smooth ice.
Ram:
An underwater ice projection from an ice wall, ice front, iceberg or floe. Its formation is usually due toa more intensive melting and erosion of the unsubmerged part.
Bare ice: Ice without snow cover.
Snow-covered ice: Ice covered with snow.
Snow cover concentration:
Concentration (aerial coverage) of snow-covered ice in an ice area in tenths.
Sastrugi:
Sharp, irregular ridges formed on a snow surface by wind erosion and deposition. On drift ice theridges are parallel to the direction of the prevailing wind at the time they were formed.
Snowdrift:
An accumulation of wind-blown snow deposited in the lee of obstructions or heaped by wind eddies.
A crescent-shaped snowdrift, with ends pointing down-wind, is known as a snow barchan.
Dirty ice:
Ice that has a mineral or organic content of natural or anthropogenic origin on the surface or in its
strata.
Frost flowers:
A growth of ice crystals by condensation from the atmosphere at points on the surface of young ice.
After formation, sea water may be drawn through the ice into the flowers. These delicate, highly saline
crystals effectively roughen the surface, often dramatically altering the appearance of sea ice inmicrowave remote sensing imagery.

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4-9. STAGES OF MELTING
Puddle:An accumulation on ice of melt-water, mainly due to melting snow, but in the more advanced stages
also to the melting of ice. Initial stage consists of patches of melted snow.
Thaw holes:
Vertical holes in sea ice formed when surface puddles melt through to the underlying water.
Dried ice:
Sea ice from the surface of which melt-water has disappeared after the formation of cracks and thaw
holes. During the period of drying, the surface whitens.
Rotten ice:
Sea ice which has become honeycombed and which is in an advanced state of disintegration.
Flooded ice:
Sea ice which has been flooded by melt-water or river water and is heavily loaded by water and wet
snow.
Shore melt:
Open water between the shore and the fast ice, formed by melting and/or as a result of river discharge.

4-10. ICE OF LAND ORIGIN
Firn:
Old snow which has recrystallized into a dense material. Unlike ordinary snow, the particles are tosome extent joined together; but, unlike ice, the air spaces in it still connect with each other.
Glacier ice:
Ice in, or originating from, a glacier, whether on land or floating on the sea as icebergs, bergy bits or
growlers.
Glacier:
A mass of snow and ice continuously moving from higher to lower ground or, if afloat, continuously
spreading. The principal forms of glacier are: inland ice sheets, ice shelves, ice streams, ice caps, ice
piedmonts, cirque glaciers and various types of mountain (valley) glaciers.
Ice wall:
An ice cliff forming the seaward margin of a glacier which is not afloat. An ice wall is aground, therock basement being at or below sea-level (cf. ice front).
Ice stream:
Part of an inland ice sheet in which the ice flows more rapidly and not necessarily in the same
direction as the surrounding ice. The margins are sometimes clearly marked by a change in directionof the surface slope but may be indistinct.
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Glacier tongue:
Projecting seaward extension of a glacier, usually afloat. In the Antarctic, glacier tongues may
extend over many tens of kilometers.
Ice shelf:
A floating ice sheet of considerable thickness showing 2-50 m or more above sea-level, attached to thecoast. Usually of great horizontal extent and with a level or gently undulating surface. Nourished byannual snow accumulation and often also by the seaward extension of land glaciers. Limited areas
may be aground. The seaward edge is termed an ice front.
Ice front:
The vertical cliff forming the seaward face of an ice shelf or other floating glacier varying in heightfrom 2-50 m or more above sea-level (cf. ice wall).

Calved ice of land origin
Calving: The breaking away of a mass of ice from an ice wall, ice front or iceberg.
Iceberg: A massive piece of ice of greatly varying shape, protruding more than 5 m above sea-level,
which has broken away from a glacier, and which may be afloat or aground. Icebergs may bedescribed as tabular, dome-shaped, sloping, pinnacled, weathered or glacier bergs.
Glacier berg: An irregularly shaped iceberg.
Tabular berg: A flat-topped iceberg. Most tabular bergs form by calving from an ice shelf andshow horizontal banding (cf. ice island).
Iceberg tongue: A major accumulation of icebergs projecting from the coast, held in place bygrounding and joined together by fast ice.
Ice island:
A large piece of floating ice protruding about 5 m above sea-level, which has broken away from an
Arctic ice shelf, having a thickness of 30-50 m and an area of from a few thousand sq.m to 500 km²
or more, and usually characterized by a regularly undulating surface which gives it a ribbed
appearance from the air.
Bergy bit:A large piece of floating glacier ice, generally showing less than 5 m above sea-level but more than
1 m and normally about 100-300 m² in area.
Growler:
Piece of ice smaller than a bergy bit and floating less than 1 m above the sea surface, a growler
generally appears white but sometimes transparent or blue-green in colour. Extending less than 1 m
above the sea surface and normally occupying an area of about 20 m², growlers are difficult todistinguish when surrounded by sea ice or in high sea state.
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4-11. SKY AND AIR INDICATIONS
Water sky:
Dark streaks on the underside of low clouds, indicating the presence of water features in the vicinity ofsea ice.
Ice blink:
A whitish glare on low clouds above an accumulation of distant ice.
Frost smoke:
Fog-like clouds due to contact of cold air with relatively warm water, which can appear over openings
in the ice, or leeward of the ice edge, and which may persist while ice is forming.

4-12. TERMS RELATING TO SURFACE SHIPPING
Beset: Situation of a vessel surrounded by ice and unable to move.
Ice-bound:A harbour, inlet, etc. is said to be ice-bound when navigation by ships is prevented on account of ice,
except possibly with the assistance of an icebreaker.
Nip:
Ice is said to nip when it forcibly presses against a ship. A vessel so caught, though undamaged, is said
to have been nipped.
Ice under pressure:
Ice in which deformation processes are actively occurring and hence a potential impediment or danger
to shipping.
Difficult area:
A general qualitative expression to indicate, in a relative manner, that the severity of ice conditions
prevailing in an area is such that navigation in it is difficult.
Easy area:
A general qualitative expression to indicate in a relative manner, that ice conditions prevailing in anarea are such that navigation in it is not difficult.
Area of weakness:
A satellite-observed area in which either the ice concentration or the ice thickness is significantly lessthan that in the surrounding areas. Because the condition is satellite observed, a precise quantitative
analysis is not always possible, but navigation conditions are significantly easier than in surrounding
areas.
Ice port:
An embayment in an ice front, often of a temporary nature, where ships can moor alongside andunload directly onto the ice shelf.

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4-13. TERMS RELATING TO SUBMARINE NAVIGATION
Ice canopy: Drift ice from the point of view of the submariner.
Friendly ice:
From the point of view of the submariner, an ice canopy containing many large skylights or otherfeatures which permit a submarine to surface. There must be more than ten such features per 30
nautical miles (56 km) along the submarine's track.
Hostile ice:
From the point of view of the submariner, an ice canopy containing no large skylights or other features
which permit a submarine to surface.
Bummock:
From the point of view of the submariner, a downward projection from the underside of the ice
canopy; the counterpart of a hummock.
Ice keel:
From the point of view of the submariner, a downward-projecting ridge on the underside of the ice
canopy; the counterpart of a ridge. Ice keels may extend as much as 50 m below sea-level.
Skylight:
From the point of view of the submariner, thin places in the ice canopy, usually less than 1 m thick andappearing from below as relatively light, translucent patches in dark surroundings. The undersurface ofa skylight is normally flat. Skylights are called large if big enough for a submarine to attempt to surface
through them (120 m), or small if not.

Acknowledgements:
The author thanks Dr. Anthony Worby (ACE CRC, Australia) for permitting citation of the
ASPeCt manual, Dr. Jennifer Hutchings (Oregon State Univ., USA) for providing valuable
information on the ASSIST protocol for Arctic sea ice, Dr. Motoyo Itoh (JAMSTEC) and Dr.
Kazutaka Tateyama (Kitami Institute of Technology) for information on sea ice observation in the
Arctic Ocean, Prof. Christian Haas (Alfred Wegener Institute) for information on the electromagnetic
induction method, Mr. Hiroki Kodama and Mr. Masato Ichikawa (Sapporo District MeteorologicalObservatory, JMA) for offering the manuals for observation of coastal ice conditions published by theJapan Meteorological Agency, Dr. Alexander Fraser (Univ. of Tasmania) for proof reading, and Ms.
Eriko Ishikawa (Hokkaido Univ.) for typing the text. The author would like to take this opportunity to
express his sincere thanks to the aforementioned people.

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Appendix: sea ice photo samples

Frazil ice

Nilas(Sea of Okhotsk)
Grease ice(Sea of Okhotsk)
Shuga(Sea of Okhotsk)(Sea of Okhotsk)(Sea of Okhotsk)(off East Antarctica)

Pancake ice

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Snow covered first-year ice

Nilas & Young ice(Sea of Okhotsk)
Small floe

(Sea of Okhotsk)
Vast floe(Sea of Okhotsk)(Weddell Sea)

Ridge

(Weddell Sea)

(Sea of Okhotsk)
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PuddleThaw holes(Arctic Ocean)
Iceberg(Arctic Ocean)
Characteristic surface snow pattern (Dune)(Weddell Sea)
Ice algae(Off East Antarctica)
Frost flowers(Sea of Okhotsk)(Off East Antarctica)# The photos in the Sea of Okhotsk were taken with the support of P/V “Soya”.

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Indirect radiation and aerosol optical thickness○Mitsuhiro TORATANI (Tokai University), Hiroshi KOBAYASHI (University of Yamanashi)

1.

Photosynthetically active radiation (PAR) and Solar radiation

1.1

Photosynthetically active radiation
Photosynthetically active radiation (PAR or EPAR) was defined by Mobley (1994).
700
700nm

PAR ≡

λ

ò hc E (λ )d λ
0

(1)

350nm

where

E0(λ): scalar irradiance: wavelengthh: Plank’s constant (6.626×10-34 Js)
c: light velocity (2.99×108 m s-1).
The unit of PAR is photons s-1 m-2 or Ein s-1 m-2. 1 Ein is 1 mol photons (6.023×1023 photons). In somecases, “photons” was described as “quanta”, and those are same.
Shipboard observation of PAR generally uses quantum meter such as LI-190. PAR is often estimatedusing only the visible wavelenghs, 400-700 nm. Omission of the near-UV band is usually permissible
since wavelengths less than 400 nm are rapidly absorbed near the water surface, except in very clear
waters (Mobley, 1994).
-Observation
The instrument should be set on the deck to prevent shadow from some structures.
In order to adhere sea salt, soot of flue gas etc., the sensor surface should be cleaned regularly.
-Data averaging
Before the time averaging, spike noises of the data should be removed, and fluctuations of thebaseline voltage of the quantum meter caused by the power supply and the sensor itself should bechecked and corrected.
The daily PAR can be obtained by the time integration for one day.
For the data of JAMSTEC (Japan Agency for Marine-earth Science and Technology), ten minutes
average of PAR is conducted because it is easier to integrate with other meteorological data. The time
is not thirty or one hour in order to avoid missing of the small time and space scale weather phenomenon
during the ship move.

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G706EN-2-Sensor calibration
Calibration of the sensor should be conducted at the proper intervals.
1.2

Global solar radiation
Solar radiation is energy that reaches the ground while solar radiation is absorbed and scattered in

the atmosphere, and is observed at wavelengths from 0.29 to 3.0 μm. Between these wavelengths, it
accounts for about 97% of the total energy of solar energy.

The total solar radiation amount is the sumof solar radiation that reaches the ground surface directly from the sun and solar radiation that reaches
the ground surface from various directions due to scattering.
Global solar radiation is observed as the irradiance received by the horizontal plane by thepyrheliometer. Unit of the amount of solar radiation is W m-2.
Details of the amount of solar radiation, the pyranometer, and the observation error of thepyranometer are described in the “Meteorological Observation Guide (in Japanese)” published on theweb (Japan Meteorological Agency, 1998).
-Observation
The instrument should be set on the deck to prevent shadow from some structures.
In order to adhere sea salt, soot of flue gas etc., the sensor surface should be cleaned regularly.
-Data averaging
Before the time averaging, spike noises of the data should be removed, and fluctuations of thebaseline voltage of the quantum meter caused by the power supply and the sensor itself should bechecked and corrected.
The weak current corresponding to about 5~10 W m-2 can be recorded over a few days, even thesolar radiation should be 0 W m-2 at night. The solar radiation at night, before the sunrise and after thesunset, should be corrected to check the occurrence and the magnitude of the night noise.
For the observation of JAMSTEC R/V Mirai, a 10-minute average value is created. To create a 10minute average, first calculate the 2-minute average. The reason for setting the minimum time to a 2minute average value is to earn a sample number of 10 samples or more. Since the recording interval isover 6 seconds, that is, less than 10 samples per minute because of recording in synchronization withother instruments, the average is 2 minutes. However, since the short-time fluctuation still remains in
the 2-minute average value, the 10-minute average value is created. If the average time is set to 30
minutes or 1 hour, there is a possibility that a weather phenomenon with a short time and space scale
may be missed when the ship is moving.
-Sensor calibration
Calibration of the sensor should be conducted at the proper intervals.

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1.3

Conversion from global solar radiation to PAR
In order to estimate photosynthetically active radiation (PAR) from the optical observations, it

requires the integration for wavelength. However, the pyranometer data does not contain the informationfor each wavelength. Therefore, conversion from global solar radiation to PAR has been proposed.
=

×

×

ℎ

The wavelength correction coefficient corrects the difference in the wavelength range (PAR: 400 to
700 nm with respect to the global solar radiation: about 0.3 to 3.0 μm).

Akitsu et al. (2015) reported

that the ratio of global solar radiation to 400-700 nm solar radiation on the ground surface varies withweather conditions and is 0.4-0.5. It is also reported as 0.45 by Meek et al. (1984). Therefore, 0.45 is
considered appropriate for simple conversion.
The correction factor for sea surface effect (photosynthesis effective radiation amount reaching thewater from the sea surface) is the following value according to Morel and Smith (1974).
2.5×1018 photons s-1 W-1(Unit: photons s-1 m-2)

This value is divided by the Avogadro number (6.023 × 1023), it can be converted to Ein.
4.2 μEin s-1 W-1(Unit: Ein s-1 m-2)

Morel and Smith (1974) found that over a wide variety of water types from very clear to turbid, theconversion factor for energy to photons varies by only ±10% about the value
2.

Sunphotometer observation
The sunphotometer is used to observe the sky condition on the ship. Sunphotometer data is used toestimate the amount of ozone concentration, optical thickness of the aerosol and water vapor from thedifference between the extraterestrial solar irradiance and the solar irradiance on the sea.
The Sunphotometer and its characteristics are described in detail in the “Technical Report on
Calibration of Radiological Observation Instruments (in Japanese)” (Working Group on Calibration ofRadiological Observation Instruments, 2015).
Sunphotometer is a compact measuring device on the handheld. We describe Microtops Ⅱ
sunphotometer. It can be measured five wavelengths. Thus, depending on what you want to measure(ozone, aerosols, water vapor), wavelength set is different.
Table 1 Observed object and wavelength set
Observed object

Wavelength set (nm)Ozone (DOBSON UNIT)

305.5, 312.5, 320

Water vapor

870, 936, 1020

Optical thickness of the aerosol

340, 380, 440, 500, 675, 870, 936, 1020

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2.1．Measurement of the optical thickness of aerosol by Sunphotometer
The direct solar light penetrates through the atmosphere to the ground surface while it attenuates to beabsorbed and scatters by air molecules and aerosols. The spectral direct solar light intensity at the surface
I (λ) is expressed as follows,=where

exp −%&'

+ &)

+ &*

+

(2)

: Spectral extraterestrial solar irradiance in average distance between Sun and the Earth(It is pre-set in the device.)&': Aerosol optical thickness,&): Optical thickness of ozone absorption&*: Rayleigh scattering optical thickness of air molecules: airmass

The &'

is calculated from I (λ) of under way observation.

The optical thickness is a value obtained by integrating the extinction coefficient, which is the sumof the scattering coefficient and the absorption coefficient, in the vertical direction. In other words, theaerosol optical thickness is the total amount of aerosol in a column expressed by the degree to lightattenuation. Therefore, it depends on the aerosol amount itself, but it varies depending on its scatteringand absorption characteristics, which is different from mass concentration and number concentration.
2.2. Observation procedure of aerosol optical thickness with sun photometer
The observation procedure is explained based on the NASA protocol for Microtop2 (Knobelspiess etal., 2003).
Preparation for observation
1．Turn on the main unit and warm up.
2．Start up GPS and check reception. When you can receive with good accuracy (Accuracy is less than
5 m), connect GPS to the main unit with a cable. The connection is completed when you hear a beep.
When the ship is moving, keep the GPS connection.
Observation
3． Turn off the power once and turn it on immediately. (Dark current is measured only just after the
power is turned on.)Record the temperature at the start of the observation.
4． Open the cover and track the sun. When the sun is catch, press Scan / Escape button to startmeasurement. Immediately after the measurement is completed, press Scan / Escape button to start
the next measurement. Repeat four times for a total of five measurements.
5． Since the optical axes of each sensor may not be aligned, it is recommended to slightly shake theinstrument.

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6． After the measurement is completed five times, turn off the power and turn it on immediately. (Darkcurrent measurement)
7． Repeat at least 20 measurements per observation. This means four sets of five sequential
measurements.
8． If the window is dirty or dusty, blow air and gently wipe it with a Kimwipe®.
9． Record the ship's barometer value.
The photo sensor inside the Sun Photometer is affected by temperature fluctuation. In order to reducethe influence of temperature fluctuation during observation, turn on the power every five times andmeasure the dark current. In the default setting of the Sun Photometer, one measurement (press Scan /Escape button) is recorded 15 raw signals, and the maximum value is stored (Scan length: 15, Numberof averaged samples: 1). It is not necessary to change the initial setting.
It is necessary to change the internal filter setting according to the power frequency of the ship. Change“Line frequency” to 60 or 50 Hz according to the power frequency of the ship. This is to prevent thenoise of the ship power from the A / D converter.
The aerosol optical thickness is calculated by subtracting the optical thickness of the air moleculesand ozone absorption from the total optical thickness. The optical thickness of the air molecules iscalculated by obtaining the atmospheric pressure from a sensor inside the sun photometer, however the
ship's barometer is more accurate for the atmospheric pressure. Therefore, a method for calculating theaerosol optical thickness by calculating the optical thickness of the air molecule based on the barometricpressure of the ship's barometer will be described.
2.3. Calculation of aerosol optical thickness
1) The optical thickness of the aerosol is derived from Eq. (3).
&'

=

/ 1
3
/2 1

,- . 0

4

− %&)

+ &*

+

(3)

（W m-2） is obtained by multiplying the

Where the extraterrestrial solar irradianceextraterrestrial solar irradiance of mean distance between solar and earth (5) and coefficient of

distance between solar and earth (6). 6 is the function of the distance the day of year (DOY).
=5∙6

6 = 1 + 0.034cos .2@
2) The airmass

(4)
DOY
ABC

3

(5)

is calculated from Eq. (6). D is the solar zenith angle which is the angle between

the zenith and the sun, and is determined by 90˚-solar altitude (˚). The solar altitude of themeasurement date and time can be obtained from the National Astronomical Observatory of Japan(NAOJ) web

Indirect radiation and aerosol optical thickness
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G706EN-6(http://eco.mtk.nao.ac.jp/cgi-bin/koyomi/koyomix.cgi ) or NOAA Solar Position Calculator(https://www.esrl.noaa.gov/gmd/grad/solcalc/azel.html ).
=

FGH.

I
L 3M
JK0 0

E

(6)

.EC NA.OOCPL0 QJ.RST3) The optical thickness of ozone &)is calculated from Eq. (7). DU (Dobson Unit) is the total

amount of ozone column. The ozone amount (DU) at the observation point and date is obtained fromthe NASA web site (http://ozoneaq.gsfc.nasa.gov/). k (λ) is an ozone absorption coefficient for eachwavelength. It is recoreded in the sunphotometer.
&)

DU

=U

(7)

E

4) Molecular optical thickness &*is calculated from Eq. (8). P is the local atmospheric pressure

measured with a meteorological instrument at the sunphotometer observation point. Note that unitofis µm, not nm.
&*

=

X

E EA.YC

0.0S0

0.00838 P A.NEBM . [\]M 1(8)2.4. Calibration of sun photometer
Calibrate the sun photometer at appropriate intervals. If you do not request a contractor, refer to“Technical report on calibration of radiation observation equipment (in Japanese)” (Working Group on
calibration of radiation observation equipment, 2015) or .Pietras et al. (2000).
References
Akitsu T., A. Kume, Y. Hirose, O. Ijima, K. N. Nasahara (2015), On the stability of radiometric ratios ofphotosynthetically active radiation to global solar radiation in Tsukuba, Japan, Agricultural and Forest
Meteorology, 209–210, pp.59–68.
http://www.jma.go.jp/jma/kishou/know/kansoku_guide/tebiki.pdf.
Japan Meteorological Agency (1998), Meteorological Observation Guide, Section 7 Global solar radiation, pp.4042, https://www.jma.go.jp/jma/kishou/know/kansoku_guide/tebiki.pdf, (in Japanese).
Knobelspiess K. D., C. Pietras, G. S. Fargion (2003), Sun-Pointing-Error Correction for Sea Deployment of the
MICROTOPS II Handheld Sun Photometer, J. Atmospheric and Oceanic Technology, Vol.20, pp.767-771.
Meek D. W., J. L. Hatfield, T. A. Howell, S. B. Idso, and R. J. Reginato (1984), A Generalized Relationship
Between Photosynthetically Active Radiation and Solar Radiation, Agronomy Journal, Vol.76, pp.939-945.
Morel A. and R. C. Smith (1974), Relation between total quanta and total energy for aquatic photosynthesis,
Limnology and Oceanography, Vol.19, No.4, pp.591-600.
Mobley C. D. (1994), Light and Water: Radiative Transfer in Natural Waters, Academic Press,
http://www.curtismobley.com/LightandWater.zip.

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Pietras C., M. Miller, E. Ainsworth, R. Frouin, B. Holben and K. Voss (2000), Calibration of Sun Photometersand Sky Radiance Sensors, NASA-Technical Memo.2000-209966, Ocean Optics Protocols for Satellite Ocean
Color Sensor Validation Revision 2, Chapter 6, pp.45-56.
Working Group on calibration of radiation observation equipment (Ministry of the Environment and Japan
Meteorological Agency) (2015), Technical report on calibration of radiation observation equipment, CGERREPORT, ISSN 1341-4356, CGER-I124-2015, http://www.cger.nies.go.jp/publications/report/i124/i124.pdf,(in Japanese).

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Notes on CTD/O2 Data Acquisition and Processing Using Seabird
Hardware and Software
A manual of “Notes on CTD/O2 Data Acquisition and Processing Using Seabird Hardware andSoftware” can be obtained from a GO-SHIP web site as below.
http://www.go-ship.org/Manual/McTaggart_et_al_CTD.pdf

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CTD Oxygen Sensor Calibration Procedures

A manual of “CTD Oxygen Sensor Calibration Procedurest” can be obtained from a GO-SHIP website as below.
http://www.go-ship.org/Manual/Uchida_CTDO2proc.pdf

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Lowered Acoustic Doppler Current Profiler (LADCP)○ Shinya KOUKETSU (JAMSTEC)

An acoustic Doppler current profiler (ADCP) attached to the frame of a Rosette water samplingsystem (CTD frame hereafter) is known as a lowered ADCP (LADCP) and can be used to measure
velocity profiles in deep layers during water sampling and measurement of water conductivity,
temperature, and depth. Because the current velocities are measured relative to the instrument, it isimportant to know the velocity of the CTD frame at all times. Two methods that are commonly used toobtain current velocities from LADCP measurements are by integration of vertical velocity shears(Fischer and Visbeck, 1993) and by using an inverse method to infer the velocities of both the CTD
frame and the currents (Visbeck, 2002). Data processing programs for both of these methods are
publicly available (Thurnherr, 2004). The Global Ocean Ship-Based Hydrographic Investigations
Program (GO-SHIP) manual (Thurnherr et al., 2010) provides detailed technical information about the
LADCP but only summarizes data processing principles.
Despite recent improvements in instrument design and data processing methods, it is often difficult to
extract accurate velocity profiles from the surface to the ocean floor from LADCP observations (ex.
due to weak echo intensities). For this reason, the data processing methods that are summarized in the
GO-SHIP manual are described here in more detail, but excluding instrument- and region-specifictechnical information.
The two available methods of velocity estimation are presented in section 1 and the data requirements
and processing procedures are described in section 2. Section 3 provides an example of an instrument
system and its configuration, and section 4 describes onboard observation procedures.

1 Methods for calculation of current velocity profiles
1-a Vertical shear of water velocity and current estimation by integration
Although LADCP data can be obtained for up to ten layers for each ping, the instrument (CTD frame)velocity is unknown, so (unlike the data from shipboard ADCPs; see Kouketsu, 2015) current
velocities cannot be measured directly. However, the vertical differences between the data measured
for each layer for a particular ping represent vertical shears of water velocity. Absolute ocean currents
velocities can then be estimated by integrating the vertical shear profiles from the available reference
velocities (Fischer and Visbeck, 1993), as described below.
A downward-looking LADCP measures current velocity relative to the CTD frame (umi,n, vmi,n, wmi,n)for the i-th ping in the n-th layer (Fig. 1). These measurements are strongly influenced by any
movement of the CTD frame.

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Figure 1 Measured velocity (um) for each LADCP ping. umi,n is the velocity measured by the i-th pingin the n-th layer. uoi,n is the ocean current corresponding to umi,n. Note that umi,n includes the CTD
frame velocity uci.

Ocean currents (uoi,n, voi,n, woi,n) are the sum of the measured velocities and the CTD frame velocities(uci, vci, wci):𝑜𝑜𝑚𝑚𝑢𝑢𝑖𝑖,𝑛𝑛= 𝑢𝑢𝑐𝑐𝑖𝑖 + 𝑢𝑢𝑖𝑖,𝑛𝑛𝑜𝑜𝑚𝑚= 𝑣𝑣𝑖𝑖𝑐𝑐 + 𝑣𝑣𝑖𝑖,𝑛𝑛𝑣𝑣𝑖𝑖,𝑛𝑛𝑜𝑜𝑚𝑚= 𝑤𝑤𝑖𝑖𝑐𝑐 + 𝑤𝑤𝑖𝑖,𝑛𝑛.
𝑤𝑤𝑖𝑖,𝑛𝑛

The vertical velocity shear (uLi,n, vLi,n, wLi,n) between the n-th and (n + 1)-th layers is calculated for alayer of thickness L, which is initially set equal to the vertical dimension of the observation cell (Fig.
1). These vertical velocity shears are not strongly influenced by movements of the CTD frame and aredefined as follows:
𝐿𝐿=𝑢𝑢𝑖𝑖,𝑛𝑛𝐿𝐿=𝑣𝑣𝑖𝑖,𝑛𝑛

𝑜𝑜
𝑜𝑜
𝑚𝑚
𝑚𝑚
− 𝑢𝑢𝑖𝑖,𝑛𝑛+1− 𝑢𝑢𝑖𝑖,𝑛𝑛+1
𝑢𝑢𝑖𝑖,𝑛𝑛𝑢𝑢𝑖𝑖,𝑛𝑛
=
𝐿𝐿
𝐿𝐿
𝑜𝑜
𝑜𝑜
𝑚𝑚
𝑚𝑚
− 𝑣𝑣𝑖𝑖,𝑛𝑛+1− 𝑣𝑣𝑖𝑖,𝑛𝑛+1
𝑣𝑣𝑖𝑖,𝑛𝑛𝑣𝑣𝑖𝑖,𝑛𝑛=
𝐿𝐿
𝐿𝐿

𝐿𝐿
𝑤𝑤𝑖𝑖,𝑛𝑛=𝑜𝑜𝑜𝑜𝑤𝑤𝑖𝑖,𝑛𝑛−𝑤𝑤𝑖𝑖,𝑛𝑛+1

𝐿𝐿

=

𝑚𝑚
𝑚𝑚
𝑤𝑤𝑖𝑖,𝑛𝑛−𝑤𝑤𝑖𝑖,𝑛𝑛+1

𝐿𝐿.

By integration of the continuously measured vertical velocity in a layer, the vertical location of theshear measurement (zi,n) is determined as a function of time. For this calculation, data from the first or
second layer (wmi,1 or wmi,2) or their average are generally used.
𝑡𝑡=𝑡𝑡𝑖𝑖

zi,n = �𝑡𝑡=0

𝑤𝑤 𝑑𝑑𝑡𝑡 + 𝐿𝐿(𝑛𝑛 − 1) + 𝐿𝐿0

Here, the distance between LADCP and the first layer is L0, and the i-th ping is emitted at time t = ti.
Note that the vertical position of the LADCP that corresponds to the first term of the right-hand side of
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the above equation can also be determined from CTD pressure data. To calculate the vertical shear(𝑢𝑢𝑧𝑧𝐿𝐿 ) of the velocities at depth z, the ensemble average of the shear measurements in a layer ofthickness h is used.

𝑢𝑢𝑧𝑧𝐿𝐿 =�ℎ𝑖𝑖,𝑛𝑛∈|𝑧𝑧𝑖𝑖,𝑛𝑛 −𝑧𝑧|<2

𝐿𝐿𝑢𝑢𝑖𝑖,𝑛𝑛/𝑁𝑁

Here, N is the number of shear measurements in the layer centered at depth z. The vertical velocity
profile is obtained by vertical integration of the averaged shears with the reference velocities (uref(zref))for each level:𝑧𝑧 ′ = 𝑧𝑧

u(z) = ∫𝑧𝑧′ = 𝑧𝑧

𝑟𝑟𝑟𝑟𝑟𝑟𝑢𝑢𝑧𝑧𝐿𝐿′ 𝑑𝑑𝑧𝑧 ′ + 𝑢𝑢𝑟𝑟𝑟𝑟𝑟𝑟 (𝑧𝑧𝑟𝑟𝑟𝑟𝑟𝑟 ).

If the LADCP is used to obtain bottom-track data, the velocity of the deepest layer is used as thereference velocity. Without bottom-track data, the reference velocity is assumed to be the average shipvelocity calculated from GPS locations at the start (xs, t = ts) and end (xe, t = te) of the cast. The
measured velocity (um(t)) is the difference between the velocities of the LADCP and the ocean current,
and the temporal integration of the LADCP velocity during the cast is equal to the distance travelledby the ship. The current velocity is the sum of the temporal integration of the velocities (u(z(t)))
obtained from the first term of the right-hand side of the above equation and the reference velocity.
The reference velocity (uref) can be calculated as follows.
𝑡𝑡=𝑡𝑡

𝑡𝑡=𝑡𝑡

𝑒𝑒
𝑒𝑒
∫𝑡𝑡=𝑡𝑡 𝑢𝑢𝑚𝑚 (𝑡𝑡) 𝑑𝑑𝑑𝑑 = 𝑢𝑢𝑟𝑟𝑟𝑟𝑟𝑟 (𝑡𝑡𝑒𝑒 − 𝑡𝑡𝑠𝑠 ) + ∫𝑡𝑡=𝑡𝑡 𝑢𝑢(𝑧𝑧(𝑡𝑡)) 𝑑𝑑𝑑𝑑 − (𝑥𝑥𝑒𝑒 − 𝑥𝑥𝑠𝑠 ).
𝑠𝑠

𝑠𝑠Note that u(z(t)) is obtained from the right-hand side of above equation with z as the temporalfunction.

1-b Inverse estimation of current and CTD frame velocities
The measured velocities from a single ping for each layer include the same CTD frame velocity (Fig.
1). Assuming that high-frequency disturbances of ocean currents during the cast were negligible, thecurrent profiles are a function of depth and individual ocean currents are measured by successive
LADCP pings, thus providing linear equations that represent the unknown ocean current and CTD
frame velocities during the cast. The unknown ocean current velocities can be obtained by solving
those linear equations (Visbeck, 2002).
In this method, it is assumed that the CTD frame velocity and the ocean current velocity are functionsof time and depth, respectively. If the vertical and temporal resolutions of the estimated ocean current
velocity profile and CTD frame velocity time series are h and τ, the measured horizontal velocity (umi,n,vmi,n) can be determined as the current (uk, vk) averaged over the depths from zk = kh to (k + 1)h and
CTD frame velocity (ucl, vcl) averaged over the period from tl = lτ to (l + 1)τ as follows:
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𝑚𝑚
𝑢𝑢𝑖𝑖,𝑛𝑛= −𝑢𝑢𝑐𝑐𝑙𝑙 + 𝑢𝑢𝑘𝑘 + εum𝑖𝑖,𝑛𝑛and εvm
are residuals.
where εum
𝑖𝑖,𝑛𝑛
𝑖𝑖,𝑛𝑛

𝑚𝑚
= −𝑣𝑣𝑙𝑙𝑐𝑐 + 𝑣𝑣𝑘𝑘 + εvm,
𝑣𝑣𝑖𝑖,𝑛𝑛𝑖𝑖,𝑛𝑛If for a particular ping the measured velocity in another vertical bin (nʹ) is observed at a different levelzkʹ, umi,nʹ can be obtained by the equation
𝑚𝑚
𝑢𝑢𝑖𝑖,𝑛𝑛′= −𝑢𝑢𝑐𝑐𝑙𝑙 + 𝑢𝑢𝑘𝑘 ′ + ε𝑢𝑢𝑚𝑚 ′ .
𝑖𝑖,𝑛𝑛In this case the frame velocity is the same as in the other bin because umi,nʹ is obtained from the same
ping as umi,n.
If the measured velocity umiʹ,nʹʹ for a different (iʹ-th) ping is the sum of the CTD frame velocity at tlʹ andthe ocean current at zk, umi,nʹʹ is defined as𝑚𝑚𝑢𝑢𝑖𝑖′,𝑛𝑛"= −𝑢𝑢𝑐𝑐𝑙𝑙′ + 𝑢𝑢𝑘𝑘 + ε.

In this case, the CTD frame velocity is different from 𝑢𝑢𝑐𝑐𝑙𝑙 , but the ocean current is the same as 𝑢𝑢𝑘𝑘 .

As shown above, equations can be obtained for all observed layers. For sufficiently large h (generally
5–20 m) and τ (e.g., during three pings), the unknown CTD frame and ocean current velocities can be
estimated by solving the equations so as to minimize residuals. In this method, additional variableconditions can easily be included. For example, if known velocity data uK are available, the following
equation can be added.
𝑢𝑢𝐾𝐾 = 𝑢𝑢𝑘𝑘 + ε.
Furthermore, the equation indicating that the integration of the CTD frame velocity for the cast period
is equal to the distance the ship has moved during the cast can also be used.

2 Data processing
Before doing the calculations described in the previous section, corrections are necessary for both thedifference between magnetic and true north (Thébault et al., 2015) and the velocity of sound in water(see Kouketsu, 2015). Furthermore, it is preferable to calculate observation depths from CTD pressure
observations rather than by the integration of vertical velocities. This preprocessing can be done withpublicly available software (Thurnherr, 2004).
The following data are needed.
 LADCP raw data CTD time series data (the average time bin of 1 second) Start and end locations of casts (from GPS data)
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 Shipboard ADCP profiles
 Local deviation of magnetic north from true north3 Instrument configurations for LADCP observations
In addition to the ADCP, the essential equipment for an LADCP survey is a battery and PCs for
operational data recording and subsequent processing. The battery provides power to the onboard PC(Windows operating system) and to the submerged LADCP. For a single LADCP operation, the
LADCP is attached to the CTD frame in a downward-looking orientation. For a dual LADCP
operation, one LADCP usually looks down and the other up. RS232C or USB cables are used toconnect the onboard PC to the ADCP and battery.
At present, a 300 kHz ADCP provided by Teledyne RD Instruments is available to members of the
Oceanographic Society of Japan; previously, a 150 kHz ADCP was provided. Higher frequency
instruments are conveniently small, but larger instruments with lower operating frequencies canmeasure currents more distant from the instrument, albeit with lower vertical resolution. Because
reflection amplitudes for deep layers in the subtropics tend to be weak, lower frequency instruments
may provide better results there.
Maintenance by the manufacturer are required every few years, during which the magnetometershould be re-calibrated.
The configuration for the LADCP is set by commands sent from the onboard PC to the instrument. For
300 kHz instruments, an 8 m cell size (and 16 observation layers per ping) is recommended. Althoughsmaller cell sizes increase noise levels, a smaller cell size (e.g., 4 m with 25 observation layers) is
worth considering for observations of deep layers, as reflections from greater depths tend to be too
weak to obtain multi-bin observations per ping. Table 1 lists the commands that control theconfiguration of an LACDP and the recommended settings. More detailed information about settings
is provided in the manufacturer’s manuals.

4 Onboard observation processes
To optimize data processing and obtain accurate current velocities, the onboard ADCP observations
should be recorded during lowering of the apparatus to within about 100 m of the seafloor and forabout 2 minutes at maximum depth to ensure capture of bottom-track data. To ensure that bottom-trackdata can be obtained, the LADCP should remain about 30 m above the seafloor. Concurrent collectionof CTD data is recommended. Both ship travel distance and CTD frame rotations should be kept to aminimum during each cast. Frame rotations can be minimized by a fin attached to the frame and by
ensuring that instruments mounted on the frame are evenly balanced. Short-term movements of the
CTD frame and ship can be inferred from CTD pressure data and GPS data, respectively. If thevariance of these short-term movements is large, the uncertainty of LADCP data may also be large. To
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avoid inaccuracies due to deviations of the orientation of the LADCP from the vertical, directional
data from the inner gyro sensor should be used. Under normal operational conditions, standard
deviations of current velocity data are typically about 10 cm/s.
Onboard observation processes can be summarized as follows.
1. Connect LADCP and PC to battery case.
2. Transfer initial settings from PC to LADCP and start LADCP observations.
3. Detach cable between battery and PC and begin CTD cast.
4. After completion of cast, with CTD frame on deck, re-connect PC to battery case.
5. Transfer data to PC by using the recovery command. Transfer generally takes over 20-30
minutes for a 6000 m cast.
6. After completion of data recovery, activate sleep command.

Table 1 LADCP configuration
Command

Configuration

CR1

Reset to default values

WM15

Use ADCP as LADCP

CF11101

Output settings

EA0

Instrument attachment angle (0 for LADCP)

EB0Alignment adjustment (0 for LADCP)

ED0Instrument depth (0 for LADCP)

ES35

Salinity for calculation of sound velocity

EX11111

Coordinate system for output. This setting means geographic
coordinates.

EZ0111101

Available sensors to output. This setting means that sound velocity isconstant, and that pressure, gyro, inclinometer, and temperature
sensors are available.

LW1

Set Narrow band mode (noisy but longer range)

LD111000000

Velocity, correlation, and echo intensity data are stored

LF176

Distance from instrument to first bin (1.76 m)

LN16

Number of observation layers (16)LS800

Observation layer thickness (8 m)

LV175

Maximum velocity (measurements above this value are discarded)

TE00:00:01.00

Ensemble period

TP00:01.00

Time between pings

CK

Save above configurations

CS

Start pinging

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References
Fischer, J. and M. Visbeck (1993): Deep velocity profiling with self-contained ADCPs, J. Atmos.
Oceanogr. Tech. 10, 764−77.
Kouketsu, S. (2015): Acoustic Doppler Current Profilers. Guideline of ocean observations, Vol. 7,
Chap. 2.
Thurnherr, A. M. (2004): How to process LADCP data with LDEO software version IX. [Available
online at http://ldeo.columbia.edu/~ant/LADCP.html]
Thurnherr, A. M., M. Visbeck, E. Firing, B. A. King J. M. Hummon, G. Krahmann, and B. Huber(2010): A Manual for Acquiring Lowered Doppler Current Profiler Data, In the GO-SHIP Repeat
Hydrography Manual: A Collection of Expert Reports and Guidelines, IOCP Report (14), ICPO
Publication Series (134).
Visbeck, M. (2002): Deep velocity profiling using Lowered Acoustic Doppler Current profilers:
Bottom track and inverse solutions, J. Atmos. Oceanogr. Tech., 19. 794−807.
Thébault et al. (2015): International geomagnetic reference field: the 12th generation. [Available
online at http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html]

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Radiometric determination of anthropogenic radionuclides in seawater
samples‫ۑ‬Michio Aoyama (Institute of Environmental Radioactivity, Fukushima University)

Abstract

Anthropogenic radionuclides in seawater have been concerned with their ecological effects andoceanographically used as a tracer. Current concentrations of anthropogenic radionuclides in the oceanic waters
are generally extremely low except areas affected by Fukushima Dai-ichi Nuclear Power plants accident in 11
March 2011. Determination of anthropogenic radionuclides in seawater has been traditionally performed withradiometric method such as J-spectrometry, E-counting and D-spectrometry. The radiometric method is still a
useful tool to determine concentrations of anthropogenic radionuclides, although recently mass spectrometricmethods have been developed extensively. In this paper, the radiometric methods to determine typicalanthropogenic radionuclides, 137Cs and 90Sr in seawater, which includes recent development of the radiometricmethods such as extremely low background J-spectrometry are presented.
Keywords: Anthropogenic radionuclides; 137Cs; 90Sr, Radioanalytical method

1. Introduction
Huge amounts of anthropogenic radionuclides have been introduced in marine environments as
global fallout of the large-scale atmospheric nuclear-weapon testing, discharge from nuclear facilities
and ocean dumping of nuclear wastes (UNSCEAR, 2000) and Fukushima Dai-ichi Nuclear Power
plants accident . The radiological and ecological effects of anthropogenic radionuclides are still worldconcern. To assess the marine environmental effects of anthropogenic radionuclides, it is significant toclarify their behavior and fate in the marine environments. Therefore, concentrations of anthropogenic
radionuclides in seawater are an important tool to evaluate the ecological effect of anthropogenic
radionuclides.
137

Cs is one of the most important anthropogenic radionuclides in the field of environmental

radioactivity because of a long physical half-life of 30.2 years. It is a major fission product (fission
yield: 6-7 %) from both plutonium and uranium (UNSCEAR, 2000). 137Cs in the ocean has been
mainly derived from global fallout (Reiter, 1978; Bowen et al., 1980; UNSCEAR, 2000; Livingston
and Povinec, 2001; Aoyama et al., 2006), together with close-in fallout from the Pacific Proving
Ground nuclear explosions (Bowen et al., 1980; Livingston et al., 2001), discharge of radioactive
wastes from nuclear facilities and others (Sigiura et al., 1976; Pentreath, 1988; Hirose et al., 1999).
137

Cs in seawater has been determined since 1957 to elucidate radioecological effects of anthropogenic

radioactivity in the marine environment (Miyake & Sugiura, 1955; Rocco & Broecker, 1963;
Shirasawa & Schuert, 1968; Bowen et al., 1980; Folsom, 1980; Nagaya & Nakamura, 1987a; 1987b;
Miyake et al., 1988; Hirose et al., 1992; Aoyama & Hirose, 1995; Hirose et al., 1999; Aoyama et al.,
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2000; Aoyama et al., 2001; Aoyama & Hirose, 2003; Hirose & Aoyama, 2003a; Hirose & Aoyama,
2003b; Ito et al., 2003; Povinec et al., 2003; 2004; Hirose et al., 2005, Aoyama et al., 2008a; 2009;2012a; 2012b; 2013, 2016). Additionally, 137Cs in seawater is a powerful chemical tracer of watermass motion at the time scale of several decades (Bowen et al., 1980; Folsom, 1980; Miyake et al.,
1988; Miyao et al., 2000; Tsumune et al., 2001; Tsumune et al., 2003a; 2003b; Aoyama et al., 2008a,
Tsumune et al., 2011) because most of the 137Cs in water columns is present as a dissolved form.
Another advantage of the use of 137Cs as an oceanographic tracer is the quantity and accessibility ofmarine radioactivity during the past four decades in contrast with other chemical tracers such as CFCs
(Warner et al., 1996).
Another important fission product is 906UZKLFKLVȕ-emitter with a half-life of 28.8 years. It has
been believed that the oceanic behavior of 90Sr is very similar to that of 137Cs because both 137Cs and90

Sr, a typical no particle-reactive element, exist as an ionic form in seawater. In contrast of 137Cs,

measurements of 90Sr in seawater are generally inconvenient because of complicated radioanalyticalprocesses. For this reason, it has been performed to estimate 90Sr activity from 137Cs activity using acertain radioactivity ratio (eg 1.6) without measuring 90Sr. However, the behavior of 90Sr in the oceandiffers from that of 137Cs; for example, a significant amount of 90Sr has been introduced to the ocean
via river discharge in contrast of 137Cs (Livingston, 1988), which is tightly retained in soil mineralsurface. In fact, the 90Sr/137Cs ratios in oceanic waters varied spatially and temporally. 90Sr may beconsidered to be a tracer of effect of river discharge to the ocean. These findings suggest that there is aneed independently to determine 90Sr in seawater.

In this paper, improved radiometric methods of 137Cs and traditional radiometric method90
Sr in seawater are presented.
2. Analytical method of 137Cs in seawater
2-1 Background137

Cs decays to stable 137%DWRHPLWȕ-UD\ NH9 DQGȖ-ray (661.7 keV). Cs, which exists ionicform in the natural water, is one of the alkali metals and chemically shows less affinity with otherchemicals. The concentration of stable Cs in the ocean is only 3 nM. Known adsorbents to collect Cs
in seawater are limited; ex., ammonium phosphomolybdate (AMP) and hexacyanoferrate coumpounds(Folsom & Sreekumaran, 1966; La Rosa, et al., 2001). The AMP has been an effective ion exchangerof alkali metals (Van R. Smit, et al., 1959). It has been known that AMP forms insoluble compoundwith Cs. AMP, therefore, has been used to separate other ions and concentrate Cs in environmental
samples. In the late 1950s, determination of 137Cs in VHDZDWHUZDVFDUULHGRXWZLWKȕ-counting because
RIXQGHUGHYHORSPHQWRIȖ-spectrometry. Two to several ten mg of Cs carrier is usually added when the
UDGLRFDHVLXP LV GHWHUPLQHG E\ ȕ-counting because of formation of precipitate of Cs2PtCl4 andcalculation of chemical yields of caesium throughout the procedure (Yamagata & Yamagata, 1958;
Rocco & Broecker, 1963). After thH GHYHORSPHQW RI Ȗ-spectrometry using Ge detectors, the AMP
SURFHGXUHZLWKȖ-spectrometry became a convenient concentration procedure for the determination in
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the environmental samples.
Traditionally (AMP) method was believed as adsorption method (Wong et al., 1994), therefore a
receipt of AMP method was very simple that pH should be adjusted between 1 and 4 by nitric acid and
AMP of 0.2 g per 1 liter sample was added without stable caesium carrier. In a modified method(Baskaran et al., 2009), they recommended to add 20 mg of stable Cs carrier to the sample, however,they did not care about stoichiometry between AMP and Cs.
In Japan, the AMP method is recommended for radiocaesium measurements in seawaters, in whichCs carrier is stated to be unnecessary (Science and Technology Agency, 1982). It, however, must be
noted that large volumes of seawater samples (more than 100 liters) were required to determine 137Cs
because of relatively low efficiency of Ge-detectors (around 10 %).
In the previous literatures, the weight yield of AMP has not been use because the chemical yield of
Cs could be obtained and the loss of small amount of AMP during the treatment did not cause serious
problems. Actually, the use of AMP reagent produced in the 1960s and in the mid 1980s gave therange from 70% to 90 % as weight yields of AMP without Cs carrier in the laboratory experiment in
1996. These weight yields are in good agreement with the records of weight yields of AMP in ourlaboratory during the 1970s and 1980s. However, the weight yield of AMP without Cs carrier had
been decreasing from the end of the 1980s and it sometimes became very low, less than 10%, in themid 1990s. To improve 137Cs determination in seawater, Aoyama et al. (2000) and Aoyama and Hirose(2008b) re-examined the ammonium phosphomolybdate (AMP) procedure. Their experiments
revealed that the stable Cs carrier of the same equivalent amount as AMP, 1 mol of Cs and 1 mol of
AMP, is required to form insoluble the Cs-AMP compound in an acidic solution (pH = 1.2 to 2.2).
Therefore, it can be said that the AMP extraction method is by generation of insoluble compounds bychemical reaction, not adsorption method. The improved method has been achieved to have highchemical yields of more than 95% for sample volumes of less than 100 liters. Another improvement is
to succeed to reduce the amount of AMP from several ten grams to 4 grams to adsorb 137Cs fromseawater samples. As a result, it has been reduced the sample volume from around 100 liters to lessthan 20 liters to be able to use high-efficiency well-type Ge-detectors. This improvement of 137Cs isfavorable to use the chemical tracer of 137Cs in the oceanographic field.
However, there was another serious problem regarding the 137Cs measurement; i.e., large-volume
sampling of more than 100 liters has been required to determine 137Cs concentrations in deep waters
because of very low concentrations of 137Cs (less than 0.1 Bq m-3). A major problem not to improvesensitivity of high-efficiency well-type Ge-detectors results in higher background accompanied with
Ȗ-spectrometry in ground-level laboratories. Especially, it is difficult to determine accurate 137Csconcentrations in deep waters (>1000 m) because of the difficulty acquiring large, non-contaminatedsamples. However, recently, Komura (Komura, 2004; Komura & Hamajima, 2004) has established anunderground facility (Ogoya Underground Laboratory: OUL) to achieve extremely low background J–
spectrometry using Ge detectors with high efficiency and low background materials.
The OUL has been constructed in the tunnel of former Ogoya copper mine (235m height from sea
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level, Ishikawa prefecture) in 1995 by Low Level Radioactivity Laboratory, Kanazawa University.
Depth of the OUL is 270 meters water equivalent and contributions of muon and neutron are morethan two orders of magnitude lower than those at ground level. In order to achieve extremely low
background J–spectrometry, high efficiency well type Ge detectors specially designed for low levelcounting were shielded with extremely low background lead prepared from the very old roof tile of the
Kanazawa Castle. As a result, background of J–ray corresponding to an energy range of 137Cs is twoorders of magnitude lower than that in ground-level facilities. A detection limit of 137Cs at the OUL is
0.18 mBq for a counting time of 10000 minutes (Hirose et al., 2005). And an underground laboratory
at Mol, Belgium, a detection limit of 137Cs is 0.1 mBq as measured for 2 weeks (Lutter et al., 2015).
There is a residual problem of underground J–spectrometry for 137Cs measurements. AMP adsorbs
trace amounts of potassium when Cs is extracted from seawater because K is a major component inseawater and radioactive potassium (40K) contains 0.0118 % of total in the natural materials. Traceamounts of 40K cause elevation of background corresponding to energy range of 137Cs due to Compton
scattering of 40K. If 40K can be removed in AMP/Cs compound samples, the full performance ofunderground J–spectrometry for 137Cs measurements is established. To remove 40K from the AMP/Cs
compound, a precipitation method including insoluble platinate salt of Cs was applied for purificationof Cs. This method performed to be able to trace amounts of 40K from the AMP/Cs compound with achemical yield of around 90 % for 137Cs (Hirose et al., 2008).
2-2 Sampling and materials

Seawater samples should be collected without contamination. When using a CTD-rosette sampler,which collected seawater of each 12 liters at 24 -36 different depth layers, before sample seawatercollection outside of the sampler bottles should be washed by clean water. When use a bucket, thebucket should be rinsed a few time before sample seawater collection.
In general, sample seawater should be filtered using a filter with pore size of 0.45 micrometer.
All reagents used for 137Cs, 90Sr and Pu assay are special (G.R.) grade for analytical use. All
experiments and sample treatments are carried out at ambient temperatures. It is very important toknow background J activity of reagents. For example (Aoyama and Hirose, 2008b), the 137Cs activity
in CsCl was less than 0.03 mBq g-1 by using extremely low background J–spectrometry and the 137Cs
activity in AMP was less than 0.008 mBq g-1., respectively. There is no serious contamination of 137Csfrom other reagents before the Fukushima accident in march 2011. It is howeveer that in some of thecommercially available AMP reagent which were produced after the Fukushima accident, a clear peakof 137Cs was observed which indicated contamination due to the accident. Therefore specila attention
is required for use them..
2-3 Recommended AMP procedure

Proposed improved AMP procedure with the ground-OHYHOȖ-spectrometer is as follows:1)

Measure the seawater volume (5-100 liters) and put into a tank with appropriate size.
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2)

pH should be adjusted to be 1.6-2.0 by adding concentrated HNO3 (addition of 40 ml
conc.HNO3 for 20 litre seawater sample makes pH of sample seawater about 1.6).

3)

Add CsCl of 0.26g and stir at a rate of 25 litre per minute or alternative method for one hour.

4)

Weigh AMP of 4g and pour it into a tank to disperse the AMP with seawater.

5)

1 hour stirring at the rate of 25 litre air per minute or alternative method.

6)

Settle until the supernate becomes clear. A settling time is usually 6 hours to overnight, but
no longer than 24 hours.

7)

Take an aliquot of 50 ml supernate to calculate the amount of the residual caesium in the
supernate.

8)

Loosen the AMP/Cs compound from the bottom of the tank and transfer into a 1-2 litre of
beaker, if it is necessary do additional step of decantation.

9)

Collect the AMP/Cs compound onto 5B filter by filtration and wash the compound with 1M
HNO310) Dry up the AMP/Cs compound for several days in room temperature11) Weigh the AMP/Cs compound and determine weight yield. This weight yield should beconsistent within uncertainty with a chemical yiled obtained by mesured stable Cs
concnetration in the supernnat collected as step 7)12) 7UDQVIHU WKH $03&V FRPSRXQG LQWR D 7HIORQ WXEH RI PO YROXPH DQG VXEMHFW WR Ȗ-ray
spectrometry2-8QGHUJURXQGȖ-spectrometry procedure13) the same procedure from step 1) to step 12)
14) Dissolve AMP/Cs compound by adding alkali solution, NaOH
15) Adjust the volume of solution ca. 70 ml and boiling to form Mo2O3 precipitate for 30 min.
16) pH should be adjusted to be ca. 8.1 by adding 2M HCl and adjust the volume of solution ca.
40 ml. Then keep room temperature 30 min. This solution should be kept one night in the
refrigerator. Remove formed Mo2O3 precipitate by filtration using 5C17) Adjust the volume of solution ca. 70 ml and pH should be adjusted to be ca. 8.1
18) Perform precipitation of Cs2Pt(Cl)4 to add chloroplatinic acid (1g/5ml D.W) at pH = 8.1 andkeep in refrigerator during a half-day.
19) Collect the Cs2Pt(Cl)4 precipitate onto filter by filtration and wash the compound withsolution (pH = 8.1)
20) Dry up the Cs2Pt(Cl)4 precipitate for several days in room temperature21) Weigh the Cs2Pt(Cl)4 precipitate and determine weight yield22) Transfer the Cs2Pt(Cl)4 precipitate into a Teflon tube of 4ml volume and subject to
XQGHUJURXQGȖ-spectrometry

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2-5 Images of recommended AMP procedure and uQGHUJURXQGȖ-spectrometry procedure at selected
step

Figure 1 Formed AMP/Cs compound at step 3

Figure 2 Formed AMP/Cs compound at step 5

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Figure 3 Formed AMP/Cs compound at step 10

Figure 4 Dissolve AMP/Cs compound by adding alkali solution at step 14

Figure 5 Formed Mo2O3 precipitate at step 16

Figure 6

The Cs2Pt(Cl)4 precipitate at step 18

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Figure 7 Dry upped Cs2Pt(Cl)4 precipitate at step 20

3. Analytical method of 90Sr
3-1 Background90

Sr decays to stable 90Zr via 90< KDOIOLIHGD\ ZLWKȕHPLWWHU NH9 WRHPLWȕ-ray (196keV). Strontium comprises about 0.025 percent of the Earth's crust and the concentration of stable Srin the ocean is 8.7x10-5 M. It is widely distributed with calcium. The chemistry of strontium is quite
similar to that of calcium, of which concentration in the ocean is 10-2M. The biological behaviors ofstrontium in the ocean are also very close to those of calcium, and then the behavior of Sr in the ocean
can be considered to be different from that of Cs.
The radiometric method of 90Sr is only E-counting. Therefore, radiochemical separation is requiredfor determination of 90Sr. An essential step in 90Sr analytical methodologies is the separation andpurification of the strontium, both to remove radionuclides which may interfere with subsequentȕ-counting and to free it from the large quantities of inactive substances typically present, i.e., calcium
in seawater. In the 1950s, oxalate technique was used to separate Sr and Ca (Miyake & Sugiura, 1955).
They applied the fuming HNO3 method for purification of Sr. On the other hand, carbonate techniques(Sugihara et al., 1959) was used for 90Sr determination for the Atlantic sample in the 1950s. Shirasawa
et al. (Shirasawa & Schuert, 1968) used similar procedures to those developed by Rocco and Broecker(1966) in which the oxalate technique was adapted. During the GEOSECS period, the oxalate
technique was applied for 90Sr determination for the world ocean (Bowen et al, 1980). Classicalmethods for the separation of strontium from calcium rely upon the greater solubility of calcium
nitrate in fuming nitric acid. Those procedures require numerous steps including repeated precipitationin strong nitric acid. Therefore, various alternative methods for separation have been proposed;
precipitation methods of strontium sulfate and strontium rhodizonate (Weiss and Shipman, 1957),
sorption of strontium on an ion-exchange resin from a solution of chelating agent such as CyDTA andEDTA (Noshkin & Mott, 1967). These methods, however, had not improved to shorter analytical steps
because the precipitation and extraction methods yield strontium fractions containing significant
amounts of calcium. In the late 1970s, Kimura et al. (1979) proposed the use of macrocyclic
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polyethers for the separation of strontium and calcium. In the 1990s, extraction chromatography, using
a solution of 4,4’(5’)-bis (tert-butylcyclohexano)-18-crown-6 in 1-octanol sorbed on an inert substrate,
has been developed for the separation of strontium and calcium (Horwitz et al., 1990). Recently
membrane filter coating crown ether was developed for separation of strontium from others (Lee et al.,
2000; Miró et al., 2002). These modern techniques have contributed for down sizing small volumes ofsamples. On the other hand, large volumes of seawater have been used for determination of 90Sr inseawater due to low concentrations of 90Sr. Therefore, the current practical method for separation andpurification of 90Sr in seawater still contains preparing precipitation at the first step.
There are some problems in the current practical methods using the carbonate technique; one is alower recovery of Sr with a range from 30-60% and another is along radiochemical separation. Since
the radioactivity of 90Sr in seawater was lower even in the surface water in present days, improvementof the Sr recovery is one of the key issues for determination of 90Sr activity in seawater. Another key
point is that Ca/Sr ratio in the carbonate precipitates is remarkably reduced from that in seawater. To
improve 90Sr determination in seawater, we re-examined the Sr separation technique for seawater
samples (Aoyama et al., 2006).
3-2 Method
3-2-1 Sampling and materials

Seawater samples should be collected without contamination. When using a CTD-rosette sampler,which collected seawater of each 12 liters at 24 -36 different depth layers, before sample seawatercollection outside of the sampler bottles should be washed by clean water. When use a bucket, thebucket should be rinsed a few time before sample seawater collection.
In general, sample seawater should be filtered using a filter with pore size of 0.45 micrometer.
90

Sr were assayed as 90<XVLQJȕ-counting following radiochemical separation described in detailas follows:
3-2-2 Preconcentration of 90Sr

Coprecipitation method has been practically used for extracting Sr from large volumes of seawater.
Both oxalate technique and carbonate technique has been carried out for preconcentration of Sr fromlarge volume water samples. The preconcentration of 90Sr due to carbonate was performed 500g
NH4Cl and 500g Na2CO3 in 100 liter seawater. To improve the lower recovery of 90Sr using carbonate
technique, it is essential to remove Mg as hydroxide at pH=12 from the sample seawater before
performing the carbonate precipitation.
3-2-3 Radiochemical separation

At the first step of radiochemical separation of Sr from Ca, Sr is separated from calcium as oxalate
precipitation at pH=4. After dissolution of oxidate precipitation, Ra and Ba are removed with Ba
chromate. After Ra and Ba are removed as precipitates, Sr is recovered as carbonate precipitation.
Further purification of Sr is carried out by using fuming nitric acid to remove Ca. After the 90Sr-90Y
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equilibrium has been attained, coprecipitation of 90Y with ferric hydroxide was formed and mounted
on a disk for counting.
3-2-ȕ-counting

ȕ-counting of 90Y were carried out by gas proportional counters for external solid samples. A
typical efficiency of 90Y counting by gas proportional counters with window is ca. 40 percent. The
detection limit of 90Y is several mBq when counting time is 360 minutes.
References
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North Pacific and marginal seas during the period from 1979 to 1988. J. Environ. Radioact., 29, 57-74.
Aoyama, M., Hirose, K., Miyao, T. & Igarashi, Y. (2000). Low level 137Cs measurements in deep seawater
samples. Appl. Radiat. Isot., 53, 159-162.
Aoyama, M., Hirose, K., Miyao, T., Igarashi, Y., & Povinec, P.P. (2001). 137Cs activity in surface water in thewestern North Pacific. J. Radioanal. Nucl. Chem., 248, 789-793.
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Seabed sediment‫ۑ‬Shigeyoshi OTOSAKA (Japan Atomic Energy Agency), Hisashi NARITA (Tokai University)

1.

Introduction
In the marine environment, anthropogenic radionuclides (e.g., cesium-137) are released byatmospheric nuclear weapon tests, nuclear accident, and operation of nuclear facilities. It is known
that some part of the radionuclides is accumulated in the seabed.

Accurate analysis of theanthropogenic radionuclides in sediment is crucial to understand their activity concentration levels aswell as deposition history to the study area. Natural radionuclides (e.g., uranium/thorium series
nuclides, carbon-14) in sediment are helpful to trace the history of sedimentation in the study area andestimate sedimentation rates of the sediment. This chapter aims to provide information for successful
observation of distribution of the radionuclides in seabed sediment. Procedures and important points
for sediment analysis are also described in Vol. 5 of this Guideline of Ocean Observations or previous
protocols (e.g., IAEA, 1993).
2.

Planning for sediment collection

2-1 Selection of sampling station

In observing radionuclides in the sediments, sampling stations should be carefully selected so thatthe samples properly preserve the bottom environment.

Especially in coastal areas, it is important tograsp approximate submarine topography and sediment characteristics in advance of the sampling, andnautical charts provide useful information for this purpose.

Locations of where sediment consists ofsand (symbol S) and mud (symbol M) are recommended for sediment collection, and those where thesediment consists of stone (symbol St) or rock (symbol R) should be avoided.

In the case of

sediments consist of gravel (symbol G) and coarse sand (symbol cS), caution is required because thesediment characteristics may change every several meters. In coastal areas, influx of material fromthe land should also be considered using information such as topography and land usage patterns. It
is also effective to create equally spaced grids in the target area and comprehensively set sampling
points along the grid. In the case of periodic surveys such as monitoring programs, even on a small
scale, the use of GPS is strongly recommended from a viewpoint of continuity of the observed data.
2-2 Uncertainties due to sediment sampling

Most radionuclides in marine sediment was originally dissolved in seawater. The dissolved
radionuclides adsorb onto the surface of suspended and/or settling particles and incorporated to theseabed. Unlike natural radionuclides, artificial radionuclides are supplied heterogeneously to themarine environment by nuclear incidents, nuclear weapons testing or regular operation of nuclear
facilities. Considering that the removal of dissolved radionuclides associates with adsorption tosuspended particles, contribution of sand/gravel and the heterogeneity of the geological characteristics
affect distribution of the radionuclides in the sediment.

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procedures should carefully be selected according to the situation.
Especially in coastal regions, heterogeneity of the grain size may alter the distribution ofradionuclides in sediment. The state of preservation of sediment-water interface during and after the
sediment coring would also affect distribution of radionuclides in the core samples. If an observationis the first trial of sample collection in the area/region or a sampling equipment, multiplicatedsampling at a representative station, and assessment of the uncertainty (reproducibility) due tooperation of new equipment are recommended. In order to overcome such heterogeneity problems,
increasing of the sample size or use of composite samples would also be effective.
3.

Sediment samplers
In this section, representative sediment samplers for measurement of radionuclides are introduced.

For a monitoring of pollutants, such as artificial radionuclides, sediment samplers must collect surface
sediment as well as suspended particles in the water-sediment interface without loss or disturbance.
In order to assess the most recent contributions of contaminants to the surface sediment, the upper
section of the sample (0–1 or 0–3 cm) should be carefully taken with the highest priority.

If theprimary purpose of sampling is to investigate the vertical distribution or sedimentation rates, coresampling without disturbance of the sedimentary layers must be applied. Researcher should selectappropriate equipment, and combine several devices as necessary.
3-1 Grab sampler

Grab samplers are commonly used for sediment sampling in brackish and estuarine waters becauseof its larger sampling area and successful collection of sandy sediment that is difficult to collect by acore sampler. Although the grab sampling is not the ideal way to observe the sediment profile, it
gives us some idea of distribution in the top 10 cm of sediment with careful sub-coring.
3-1-1 Ekman-Burge sampler

Ekman-Burge samplers are light weighted equipment (5–10 kg) with a sampling area of about 15
cm × 15 cm. It can collect a sample up to 3 L in volume. After arriving at the bottom, a drop
messenger triggers to release shovel blades for sediment collection. It is designed to collect soft
surface sediments manually in the absence of strong currents. The lack of sample disturbance, squarecross section and moderate penetration make it suitable for collection of the surface sediments.
Because of its lightweight and easy handling, it is well-suited for small boat operations.
3-1-2 Smith-McIntyre sampler

Smith-McIntyre sampler can collect samples of up to 20 L of fine-grained and sandy sediments.
Unlike the Ekman-Burge sampler, Smith-Macintyre sampler is designed to release the shovel blades at
a time when the sampler touches the seafloor.
3-2 Core sampler

Sediment cores provide helpful information for estimating the sedimentation rate, the history of
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contaminant discharge to the water system, and the inventories of pollutants.

In collection of a coresample, it is important to preserve the original layers of the sediment without disturbance and to avoid
losing the surface layer which may hold the most recent pollutants.
The diameter of coring tube should be as large as possible to provide sufficient material for
analysis.

Coring tubes with a diameter of about 5–12 cm are commonly used. When the coring

tube penetrates into the sediment, deformation of the sediment layers may occur by friction between
the inner wall of the tube and sediment (a dome-like structure in which the sediment layer becomes
convex shaped in the coring tube).

Especially when the penetration speed is fast and the contact areaof the inner wall of the tube per unit mass of the sediment is large, the extent of deformation becomeslarge. Generally, when the diameter of the coring tube is 70 mm, the extent of deformation is about 5
mm outside the sediment core, and contamination of the sample (contamination of the upper layer
sediment in the lower layer) occurs in this range. In the case of sediments containing sand or larger
grain sizes, or sediments with brittlestars (e.g. Ophiura ophiura) on the surface, they are dragged
along the inner wall of the tube, and the sediment particles near the surface may move downward.
Such contamination can be prevented by removing about 5 mm of the outer peripheral part of thesediment column.
3-2-1 Gravity corer

A gravity corer is an open tube fitted with a weight so that gravity can force it sufficiently deep
into the sediment to isolate a sediment sample.

The simplest possible corer used in shallow

environments consists of a piece of plastic tubing and a weight.

After this type of sampler ispenetrated into the sediment, the top of the coring tube is sealed and retrieved to the boat.
3-2-2 Multiple corer

In a multiple corer, seawater in a cylinder installed at the upper center of the sampler works as adamper, and a multiple polycarbonate coring tubes attached to the lower frame are inserted into thesediment without disturbing the sediment-water interface at a very low speed (1 cm/sec or less). A
guide frame surrounding coring tubes helps to maintain the tubes in a vertical position. The frame
also permits installation of a mechanism that seals the bottom of the coring tube immediately after the
tube is extracted from the sediment. A bottom core seal improves the success of capturing sedimentin the coring tube without an internal core catcher. The core seal also enables to collect overlying
water as well as sediment core.
2-3-2-3 Box corer

Box corer has a box with surface area up to 2,500 cm2 (50 × 50 cm) and a maximum penetration
depth of about 50 cm, and is suitable to collect large volumes of sediment. As the winch begins toretrieve the corer after the corer penetrated into the sediment, a single spade or two opposing jaws withrubber sealing surfaces are pulled through the sediment to a position in contact with the cutting edgesof the box. By the larger surface area of sediment collection, compared to a tube coring, box corer isable to minimize the change in the thickness of the sediment during the coring. The box core sample
is often subsampled by pushing clean coring tubes into the sediment for a further analysis. In order
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to avoid shortening during the penetration of sub-coring tube, it is preferable to use a tube with adiameter at least 50 mm of which side wall is as thin as possible. When penetrating the sub-corer
into the sediment, do so when overlying water is on the sediment sample in the box.

Although a box

corer can collect an excellent sample in muddy sediments, it is difficult to collect sandy sedimentbecause the sealing spade is not sufficiently tight to trap water. If a box corer is retrieved with theabsence of overlying water on the sediment sample, there is a possibility that the surface sediment was
disturbed or partly lost. In such a case, it is recommended to collect the sample again.
3-2-4 Piston corer

In general, conventional piston cores are used when long cores (2–30 m) in fine-grained
unconsolidated sediments are required for analysis of sedimentary processes in several thousands tomillions of years. Ships need to be equipped with hydraulic cranes, winches and enough space forcore handling.

After the bottom of the piston, the barrel surrounding the piston (coring tube)

penetrates into the sediment while keeping the piston on the bottom surface.

When the barrel

penetrates the sediment, a negative pressure occurs in a small space between the piston and thesediment, and the friction between the inner wall of the barrel and the sediment is reduced.

By thenegative pressure, the barrel is more likely to penetrate into the sediment. Since the piston functions
as a "plug" when the barrel is pulling out, the core sample can be recovered without falling while
keeping the sedimentary layers. However, for the successful sampling, the piston must be held on
the seabed surface when the barrel is penetrating into the sediment.
4.

Collection of sediment samples

4-1 Sampling record

As general information of sediment sampling, following items should be recorded for every
collection of sediment.
Sampling date and time
Researcher/Operator
Location
Bottom depth
Wave and heave heights
Size classification (granule, sand, silt, clay etc.: e.g., ISO, 2002)
If available, detailed cruise data and tension record of the winch would also be helpful for replicate
collection at the same location.
4-2 Subsampling from grab sampler/Box corer

After retrieving a sampler, confirm that the sediment sample was successfully collected in thebucket/box. If the sample is not sampled horizontally, if the sample overflows, or if the overlying
water is not retained, it should be sampled again because a part of the sediments may be lost during thesampling.
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Retrieved sampler is tightly lashed on deck to avoid slipping.
When sub-coring is preformed, a sub corer with 40 ~ 80 mm in diameter is slowly penetrated into
the sediment. See section 4-3 for processing after subsampling.
Drain overlying water by pumping or siphoning with silicone tube (ID: 5–10 mm).

It is

recommended to use a pump to prevent water from flowing back and disturb the sediment surface.
After removing the overlying water, measure the thickness of sediment and recorded.
Considering the shape of the sediment box, measure the thickness at multiple points as necessary sothat the approximate volume of the collected sediment can be estimated.
Place a stainless (or plastic if necessary) container (50 mm height) under the sampler.

Open thejaws and scrape the sample in the bucket.
Homogenate sample with a stainless hand shovel, packed into plastic bag and sealed.
As necessary, it is possible to penetrate a clean acrylic tube into the sediment and obtain a sub-core(see section 4-3 to process the core samples). This step must be carried out before draining theoverlying water.
4-3 Subsampling from core sampler

Carefully seal the bottom of coring tube with a spatula (the width of spatula must be larger thandiameter of coring tube) and remove the coring tube from the corer.
Immediately seal the both ends of corer with rubber plugs, and allowed to settle suspended
particles in the overlying water of the sediment surface. Care should be taken not to give shock sothat sediments will not be disturbed.

As necessary, the rubber plugs are sealed with plastic seal tape(c.a. 50 mm width).
Before starting the core slicing, prepare water (surface seawater or tap water will be acceptable if
there is no significant contamination of target radionuclide) in a bucket.

Prepare bags or bottles forstorage of subsamples and note sampling date, station ID, sampling layer in advance to processsamples.

Plastic seal bags or plastic bottles with seal top are useful for subsampling.

After at suspended particles in the bottom water is settled, set the coring tube on a cutting piston
and release the top plug. Carefully release the bottom plug, immediately slide spatula between thecoring tube and bottom plug, and remove the bottom plug.
Carefully slide out the spatula and insert the core into the piston from the bottom of the coringtube.
As necessary, drain the overlying water by a pump or siphon with silicone tube (ID <5 mm). Useof a pump is recommended to prevent disturbing the surface sediment by water from flowing back to
the coring tube. The piston should be kept pushing up (core is pushed down when using a fixedheight) during the collection of overlying water.

Weaken the flow rate of the pump at the end, fix thetip of the tube on the water surface, and suction the water and air.
When it is not necessary to sample the overlying water, push the piston up to allow the overlying
water overflow. When the sediment-water interface approaches to 1~2 cm below the top end, set water
absorbent material (Kimwipes are useful) on the overlying water and slowly push up the piston. The
absorbent should not be contact with sediment surface as much as possible.
Guideline of ocean observations Vol. 9 Chap. 2 Seabed sediment© Shigeyoshi OTOSAKA, Hisashi NARITA 2018 G902EN:001-008

G902EN-6

Push up the piston until the demanded thickness of sediment comes out. If the sediment has highwater content and it is expected to overflow by the uplifting, scoop the sediment for given thickness of
sediment layer and stored in a subsample bag/bottle.
Using a spatula, chip off the smearing sediment along the inner wall of coring tube.

It is efficient

to make a hexagon-shaped core.
Slide a spatula along the line of the top of the coring tube and cut the sediment.

During thisprocess, do not move the spatula vertically to prevent disturbing sedimentary layers in the core.
Store the cut subsample in a bag/bottle.
Before cutting the subsequent layer, spatula is washed with water and wiped.
5.

Transport and storage
After the collection of the sediments using grabs or corers at the field site, the samples must betransported to the laboratory without altering properties of the original material. This involves special
steps to reduce potential contamination and to minimize mixing for biological, chemical, and physicalanalyses.
When carrying core samples to laboratory on land, it should be secured in a vertical position so as
not to disturb the sedimentary layer.

For such cores, it is often advantageous to completely fill the

space from the water sediment interface to the top of the coring tube with local water and to remove
any air bubbles that may be trapped under the core cap.
When carrying the core by a vehicle, an enough cushioning material should be used to suppress
vibration.
If the core cannot be held in a vertical position during cutting and transport, the surface of the core
is covered with a Teflon sheet (about 1mm thick and cut to the interval diameter of the coring tube)
followed by a PVC well plug.
Cryopreservation of core sample is not recommended.

When it is necessary to store cores in afreezer, take notice of the change in core length due to expansion and the vertical movement of porewater in the sediment column. Additionally, when frozen core samples are cut, they should beprocessed without thawing.
6.

Analysis of sediment properties
In the analysis of distribution of radionuclides in seabed sediment, the following sediment

properties are especially important.
Percentage of water content (see also Vol. 5, Chap. 2 of this Guideline of Ocean Observations).
Loss on ignition, organic matter or total organic carbon (TOC) content (Vol 5, Chap. 3) .
Grain size distribution (Vol. 5, Chap. 4).
Dry bulk density (Vol. 5, Chap. 2)

7.

Processing sediment samples for analysis

7-1 Drying
Guideline of ocean observations Vol. 9 Chap. 2 Seabed sediment© Shigeyoshi OTOSAKA, Hisashi NARITA 2018 G902EN:001-008

G902EN-7

Drying step is required because concentrations of contaminants in sediments are usually reported
on a dry-weight basis. The drying step also provides an opportunity to calculate water content bysimply weighing the sample before and after drying.

Water content is a fundamental parameter ofthe sedimentary environment. The water content is also applied in calculation of the salt separated
from the seawater by the drying. The drying procedures are as follows. Throughout the drying
process, attention should be payed not to make cross contamination between subsamples.
Gently mix the wet sediment subsample by stainless spoon and reassemble aggregation.
Put the sample into a pre-weighed container, and measure total weight. The balance should bechosen so that the number of effective digits is 4 or more.
Place the sample in an oven at 60~105 °C (depends on element/isotope of interest).
Allow the sample at room temperature and measure the total weight.
Crush aggregates in a ceramic mortar, remove pebbles and remove stone, shell and organisms (fish,
benthos, seaweeds etc.) and organisms with 2 mm sieve.

In this procedure, care should be taken not

to “grind” the sediment particles.
As necessary, reduce the sample size and store the dried sample in appropriate sealed vessel (seesection 7-3).
7-2 Homogenization

Artificial radionuclides are often adsorbed heterogeneously onto the surface of sediment particles.
In case a large amount of samples must be handled, an automatic homogenizer (mixer consists of a Vor cyrinderical-shaped rotating vessel) is helpful for homogenization. When such a homogenizer isused, all sediment samples, including fine particles and “dust” (which may have a relatively highcontent of radionuclides), in the vessel must be recovered.
7-3 Reduction of sample size

If large amount of sample for analysis was collected, the size of sample is reduced by thefollowing procedures. Theoretically, it can be estimated that satisfactory homogeneity (less than 3 %of uncertainty due to processing sample) is obtained by subsample sizes larger than 100 mg withparticle sizes <0.08 mm (IAEA, 1993).
Incremental method:

Spread powdered sample on a clean and smooth board or sheet, let the

sample square or rectangle with 15–25 mm in thickness, and divide equally into 9 blocks. Scoop
samples from each block with an increment spoon, and repeat until the required amount of sample isobtained. In this method, subsamples should be taken from bottom of each block.
same number of times must be taken for all blocks.
Dividing method:

Repeat dividing the sample size by a riffle sampler.

Automated method: Use a specialized device such as cascade and rotary splitter.
Detailed procedures and instruments are described in JIS (1992).
7-4 Preparation for determination of radionuclides
7-4-1 Nondestructive analysis

Guideline of ocean observations Vol. 9 Chap. 2 Seabed sediment© Shigeyoshi OTOSAKA, Hisashi NARITA 2018 G902EN:001-008

In addition, theG902EN-8

Gamma-ray spectrometry is the representative nondestructive technique for the determinationof activity concentration of radionuclides from natural or anthropogenic origin. In the gamma-ray
spectrometry, a dried and powdered sample is sealed in a pre-weighed plastic bottle for measurement.
The bottles must have the same dimension of that of a certified reference material used for calibrationof high-purity Germanium (HPGe) detector.
When measuring activity of radium-226 indirectly from activities of lead-214 or bisemous-214, it
is necessary to prevent escape of Rn-222 (a daughter nuclide of Ra-226 and a gas component). This
process helps to establish the radioactive equilibrium between Ra-226 and Pb-214 or Bi-214. For
this purpose, the surface of sample in the container is covered with an acrylic disk and sealed withepoxide resin.
7-4-2 Analysis that requires decomposition, separation and purification of sample

For radioanalytical techniques by alpha-/beta- counting or a high-resolution mass spectrometry,sediment samples must be decomposed by an appropriate method, followed by separation andpurification of the target elements/radionuclides. When handling radionuclides as yield tracers, caremust be taken so that they do not contaminate other samples by diffusing into the working
environment and equipment. On the other hand, especially for mass spectrometry, it is necessary to
prevent contamination of the working solution by environmental material (i.e. dust, gas etc.). Whenselecting the appropriate method for measurement of the target radionuclides, they also should
understand correctly about the precautions for the analysis.
References
ISO (2002):

Geotechnical investigation and testing – Identification and classification of soil – Part 1:

Identification and description. ISO 14688-1:2002. International Organization for Standardization, Geneva, 12
pp.
JIS (1992): Particulate materials –General rules for methods of sampling. Japan Industrial Standards
Committee, Tokyo, 86 pp. (in Japanese)
IAEA (1993): Collection and preparation of bottom sediment samples for analysis of radionuclides and traceelements. IAEA-TECDOC-1360. International Atomic Energy Agency, Vienna, 130 pp.
MEXT (1983): Collection of environmental sample.

Ministry of Education, Culture, Sports, Science andTechnology, Tokyo, 135 pp. (in Japanese)

Guideline of ocean observations Vol. 9 Chap. 2 Seabed sediment© Shigeyoshi OTOSAKA, Hisashi NARITA 2018 G902EN:001-008

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G904EN-1

Plankton and BenthosżHideki KAERIYAMA (-DSDQ)LVKHULHV5HVHDUFKDQG(GXFDWLRQ$JHQF\)

1. Sample Collection and Storage
1-1 Plankton

Phytoplankton and zooplankton play an important role in marine ecosystems as a primary producer
and secondary producer, especially zooplankton act as a vital link between primary production(phytoplankton) and higher trophic production through food webs. These organisms also play animportant role in understanding the radionuclides cycling within the ocean, and the transfer ofradionuclides from seawater to marine organisms. However, the activity concentration ofradionuclides found within zooplankton and phytoplankton is low. In particular, the activity
concentration of anthropogenic radionuclides is considerably low for long lived radionuclides ingeneral. Analyze the activity concentration of artificial radionuclides in zooplankton andphytoplankton, it is necessary to collect a large sample volume. To collect zooplankton samples, it isrecommended to use large mouth-opening plankton net (for example, an Ocean Research Institute(ORI) net or Bongo net). The oblique hauling to collect plankton several times is also recommended
through the water to a depth that is approximately equivalent to the depth of the mixed layer or to thedepth directly below the thermocline. Because we can expect large biomass of zooplankton existed
within that layer. Furthermore, when collecting samples of large crustacean plankton such as
euphausiids and micronekton, which are large and have strong swimming abilities, it is best to uselarger nets or trawls allowing high speed tow such as Isaacs-Kidd Midwater Trawl Net (IKMT) or
Matsuda, Oozeki and Hu Midwater Trawl (MOHT) (cf. Oozeki et al., 2004, Wiebe and Benfield,2003). Once the net has been pulled up onto the board, the outer surface of the mesh should bethoroughly washed in seawater, and the plankton sample that has accumulated in the cod end of the net
should be recovered. To aid in the data interpretation, a portion of the sample should be used todetermine ecological information of zooplankton community such as the biomass, species composition,and numerical density (Kaeriyama et al., 2008, Kitamura et al., 2013, Takata et al., 2015). For this, aflow meter should be attached to the plankton net and quantify the amount of water that has been
filtered. The remaining portion of the sample should be drained, placed in a Ziploc bag, frozen, andstored. Additionally, it is recommended to obtain the activity concentration of the radionuclide ofinterest in the seawater (dissolved matter) at the depth at which the plankton net is hauled, to calculate
the concentration factor (IAEA, 2004), which is a useful value for data interpretation (Tateda, 1998;
Kaeriyama et al., 2015). Furthermore, in cases when the radionuclide activity concentrations arecompared among different types of zooplankton, using the concentration of stable isotopes in eachtype of zooplankton is an effective method for the analysis because it is difficult to collect a large
quantity of a single species of plankton. When using the stable isotope concentration as an indicator of
the radionuclide activity concentration, it is assumed that isotopic fractionation seen in hydrogen,carbon, nitrogen, oxygen, and sulfur does not occur (Hidaka and Akagi, 2002). The sample collected
Guideline of ocean observations Vol. 9 Chap. 4 Plankton and Benthos© Hideki KAERIYAMA 2018 G904EN:001-005

G904EN-2

through the plankton net should be transferred to a large Petri dish, and individual organisms of theplankton type of interest should be selected one by one using tweezers or a pipette on the board. For
large crustacean plankton such as euphausiids, and copepods, several tens of organisms should becollected. The water on the surface of the organisms should be removed, and the organisms should be
frozen. The stable isotope concentration can be analyzed by drying the sample, dissolving it in acid,and analyzing the dissolved sample using ICP-AES or ICP-MS (Masuzawa et al., 1988, Marumo et al.,1998). Because exclusively collecting a large amount of phytoplankton is extremely difficult, the useof a large volume in-situ filtration system (Bishop and Edmond, 1976, Aono et al., 2008), or a
cartridge filter using a seawater collection system on the board may be considered (The
Oceanographic Society of Japan, the Great East Japan Earthquake WG /Analysis SWG, 2011). In sucha case, the sample obtained is a suspended solid consisting mainly of phytoplankton. When using alarge volume in-situ filtration system, one recommended method to collect the samples efficiently is tocheck the vertical profile of the chlorophyll fluorescence beforehand and perform the observation at
the depth where the peak is found. The filter paper that is used for collection should be marked with its
weight beforehand so that the weight of the dried sample can be calculated afterwards. The amount offiltered water measured by the flow meter should also be recorded. The filter paper with thesuspension sample obtained through the cartridge filter should be frozen and carried back to the lab.
When filtering the seawater, a flow meter should be installed on the outlet of the housing of the
cartridge filter, and the amount of filtered water should be recorded. If it is expected that the seawatercontains a high activity concentration of radionuclides, the seawater collection system, hose, andhousing of cartridge should be thoroughly rinsed with field seawater, the seawater inside the systemshould be replaced, and the housing should be thoroughly washed with distilled water.
1-2 Benthos

Benthos collection is performed with the general collection equipment (sledge nets, dredge nets,
and trawl nets. Refer to the chapter on benthos, Volume 6 Chapter 2 in this Guideline of Ocean
Observations). Afterwards, the organisms should be placed in a Petri dish filled with seawater filteredon-site, and organisms were sorted as possible as in details. During this step, it is important to remove
the sediment particles stuck to the benthos as much as possible, using the filtered seawater. For theradioisotopes of conservative elements, such as radiocesium, the sample should be washed withseawater containing the same level of activity concentration of radionuclides as the on-site seawater,
to avoid artificial changes in the radionuclide activity concentration of the samples. After being sorted,
the samples should be frozen and stored. Depending on the purpose of the investigation, theresearchers should consider processing the sample, such as incubating the sample for a certain period
in the filtered seawater to empty the digestive systems of the organisms, to eliminate the effect of thegastrointestinal content. For organisms such as mollusks and crustaceans for which it is possible toseparate their molluscan part from the exoskeleton, it is desirable to dissect the organism and analyze
these parts separately (Sohtome et al., 2014). When collecting benthos, it is recommended to alsocollect a sample of the sediment on the ocean floor, which is the habitat of the benthos, by using abottom sampler and to measure the activity concentration of radionuclides in the sample of sediment.
Guideline of ocean observations Vol. 9 Chap. 4 Plankton and Benthos © Hideki KAERIYAMA 2018 G904EN:001-005

G904EN-3

2. Measurement Preprocessing
The best preprocessing and measurement methods depend on the radionuclide of the interest. For
general preprocessing methods and radionuclide measurement methods, please refer to the radiation
measurement method series published by the Ministry of Education, Culture, Sports, Science andTechnology, Japan (Nos. 2, 7, 9, 12 and 16). Also, please refer to gamma ray spectral analysis
techniques for emergency situations (Nos. 24 and 29). Here, we describe several points to be cautious
about when preprocessing samples for measurements using germanium semiconductor detectors for
gamma ray emitting isotopes including radiocesium. When the activity concentration of radionuclides
is expected to be high, the raw sample of the frozen zooplankton and benthos can be directly used forthe measurement. When defrosting the sample at room temperature, to prevent the loss of the cellular
fluid, the sample should be divided into small portions of an amount that can fit inside themeasurement container, and defrosted in a container. If the measurement container is not disposable,
the sample should be placed in a plastic bag before being placed into the measurement container. To
prevent contamination of the detector, the measurement container containing the sample should also
be placed in a plastic bag. When the activity concentration of anthropogenic radionuclides is expected
to be low, it may be difficult to conduct the measurement using the fresh sample directly. In this case,the water should be removed from the sample to reduce its volume. For this, the sample should befreeze-dried or dried using a dryer. The dried sample should be homogenized by grinding in a mortar.
The sample should be filled into the container and measured using a germanium semiconductor
detector. If further volume reduction is needed, the sample can be incinerated at an appropriate
temperature (please refer to Volume 9 Chapter 3 in this Guideline of Ocean Observations (underreview) for incineration methods). In cases where a large amount of phytoplankton suspended mattersample has been collected with a large volume in-situ filtration system, the sample can be dried,
removed from the filter, ground in a mortar, placed in a pre-weighed measurement container, andmeasured using a germanium semiconductor detector. In cases where the sample is small, the sample
can be dried, cut along with the filter, ground in a mortar, and used to fill the measurement container.
The cartridge filter should be cut and should have the center part and core separated from the filter.
The filter part should be incinerated to reduce its volume and used to fill the measurement container.
For samples such as radioactive strontium and plutonium isotopes that require chemical separation
or extraction, procedures such as acidic cleavage and solvent extraction should be performed for thedried or incinerated sample in the same manner as for the sediment, to use it as an analysis sample(refer to Volume 9 Chapter 2: Marine sediment in this Guideline of Ocean Observations). When
analyzing certain types of phytoplankton in which the cell wall contains silica, such as diatoms, it isnecessary to select the appropriate method for completely dissolving the sample as per the sample
characteristics, such as using hydrochloric acid for dissolving silica. When analyzing tritium, the waterin the freeze dryer’s cold trap should be recovered after the sample is freeze-dried and used as the
sample for analysis as free water tritium (FWT). Organically bound tritium (OBT) can be analyzed in
the same manner as large organisms by freeze-drying the sample, placing the dried sample in a quartz
tube, and completely burning the sample using a combustion device while running oxygen over the
Guideline of ocean observations Vol. 9 Chap. 4 Plankton and Benthos © Hideki KAERIYAMA 2018 G904EN:001-005

G904EN-4

sample. The generated water vapor should be collected in a cold trap and used as the sample foranalysis. For both FWT and OBT, the sample should be distilled and measured using a low
background liquid scintillation counter to remove the organic material. For detailed methods ofanalysis, please refer to No. 9 of the radiation measurement method series published by the Ministry of
Education, Culture, Sports, Science and Technology (Ministry of Education, Culture, Sports, Scienceand Technology, 2002).

References
Aono, T., M. Kusakabe, T. Nakanishi, M. Yamada, S. Kaneko, T. Nakamura, K. Hori, and J. K. B. Bishop(2008): Large Volume in-situ filtration and concentration system for measurements of low-level radioactivity
in seawater. J. Advanced Mar. Sci. Technol. Soc., 14-2, 39-50.
Bishop, J. K. B., and J. M. Edmond (1976): A new large volume filtration system for the sampling of oceanic
particle matter. J. Mar. Res., ௅
Hidaka, H., and Akagi, T. (2002): Introduction of Isotopic ratio analysis–Definitions and standard materials forisotopic ratios (in Japanese), Bunseki, 2002, Vol. 1. 2-9.
IAEA (2004): Sediment distribution coefficients and concentration factors for biota in the marine environment.
Technical Reports Series No. 422. IAEA, Vienna.
Kaeriyama, H. T. Watabe, and M. Kusakabe (2008): 137Cs concentration in zooplankton and its relation totaxonomic composition in the western North Pacific Ocean. J. Environ. Radioact.௅
Kaeriyama, H. K. Fujimoto, D. Ambe, Y. Shigenobu, T. Ono, K. Tadokoro, Y. Okazaki, S. Kakehi, S. Ito, Y.
Narimatsu, K. Nakata, T. Morita, and T. Watanabe (2015): Fukushima-derived radionuclides 134Cs and 137Cs
in zooplankton and seawater samples collected off the Joban-Sanriku coast, in Sendai Bay, and in the
Oyashio region. Fish. Sci.௅
Kitamura, M., Y. Kumamoto, H. Kawakami, E. C. Cruz, and K. Fujioka (2013): Horizontal distribution of
Fukushima-derived radiocesium in zooplankton in the northwestern Pacific Ocean. Biogeosciences, 10,௅
Marumo K., T. Ishii, Y. Ishikawa, and T. Ueda (1998): Concentration of elements in marine zooplankton fromcoastal waters of Boso Peninsula, Japan. Fish. Sci.௅
Masuzawa, T., M. Koyama, and M. Terazaki (1988): A regularity in trace element contents of marine
zooplankton species. Mar. Biol., 97, 58௅
Ministry of Education, Culture, Sports, Science and Technology (1990) Radiation measurement methods seriesNo. 12: Plutonium analysis method (in Japanese)
http://www.kankyo-hoshano.go.jp/series/lib/No12.pdf
Ministry of Education, Culture, Sports, Science and Technology (1992) Radiation measurement methods series
No. 7: Gamma ray spectrometry using germanium semiconductor detector (in Japanese)
http://www.kankyo-hoshano.go.jp/series/lib/No7.pdf
Ministry of Education, Culture, Sports, Science and Technology (1992) Radiation measurement methods seriesNo. 24: Sample preprocessing methods for gamma ray spectrometry for emergencies (in Japanese)
Guideline of ocean observations Vol. 9 Chap. 4 Plankton and Benthos © Hideki KAERIYAMA 2018 G904EN:001-005

G904EN-5

http://www.kankyo-hoshano.go.jp/series/lib/No24.pdf
Ministry of Education, Culture, Sports, Science and Technology (2002) Radiation measurement methods series
No. 9: Tritium analysis method (in Japanese)
http://www.kankyo-hoshano.go.jp/series/lib/No9.pdf
Ministry of Education, Culture, Sports, Science and Technology (2003) Radiation measurement methods seriesNo. 2: Radioactive strontium analysis method (in Japanese)
http://www.kankyo-hoshano.go.jp/series/lib/No2.pdf
Ministry of Education, Culture, Sports, Science and Technology (2003) Radiation measurement methods seriesNo. 16: Environmental sample collection methods (in Japanese)
http://www.kankyo-hoshano.go.jp/series/lib/No16.pdf
Ministry of Education, Culture, Sports, Science and Technology (2004) Radiation measurement methods seriesNo. 29: Gamma ray spectral analysis method for emergencies (in Japanese)
http://www.kankyo-hoshano.go.jp/series/lib/No29.pdf
The Oceanographic Society of Japan, the Great East Japan Earthquake Working group/Analysis and Sampling
Subgroup (2011): Collection of marine samples for measuring radiation/Basic recommended method formeasurement (in Japanese)
http://kaiyo-gakkai.jp/jos/wp-content/uploads/2013/01/Manual_22May2011.pdf (2017/8/21 accessed)
Oozeki, Y., Hu, F, Kubota, H., Sugisaki, H., Kimura, R. 2004. Newly designed quantitative frame trawl forsampling larval and juvenile pelagic fish. Fish. Sci., 70, 223௅232.
Sohtome T., T. Wada, T. Mizuno, Y. Nemoto, S. Igarashi, A. Nishimune, T. Aono, Y. Ito, J. Kanda, and T.
Ishimaru (2014): Radiological impact of TEPCO’s Fukushima Dai-ichi nuclear power plant accident on
invertebrates in the coastal benthic food web. J. Environ. Radioact.௅
Takata, H., M. Kusakabe, and S. Oikawa (2015): Radiocesiums (134Cs, 137Cs) in zooplankton in the waters of
Miyagi, Fukushima and Ibaraki Prefectures. J. Radioanal. Nucl. Chem.௅
Tateda, Y. (1998): Concentration factor of 137Cs for zooplankton collected from the Misaki coastal water. Fish.
Sci.௅
Wiebe, P.H. and Benfield, M.C. (2003): From the Hensen net toward four-dimensional biological oceanography.
Prog. Oceanogr., 56, 7௅136.

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G1002EN-1

Petroleum and Hydrocarbons
Hideaki MAKI, National Institute for Environmental Studies

1. Introduction
Analytical methods for the qualification and quantification of hydrocarbons in marine
environments are needed for identifying the sources of oil spills, for monitoring pollution status after
oil spills, for examining the pyrogenic and terrigenous hydrocarbon content of sediment, and forstudying the production of aliphatic hydrocarbons produced by marine organisms and plants.
Polycyclic aromatic hydrocarbons (PAHs) can be classified as being of either petrogenic or
pyrogenic origin. The majority of petrogenic PAHs are low-molecular-weight compounds with 2 or 3
rings and their alkylated derivatives (e.g., naphthalene, fluorene, phenanthrene, dibenzothiophene, andanthracene), but includes smaller amount of anthracene and PAHs 4 or more rings (e.g., pyrene,
fluoranthene

andbenzopyrenes).

In

contrast,themajorityofpyrogenic

PAHs

are

high-molecular-weight compounds with 4 or more rings. One exception to this general rule is heavy
fuel oil, obtained as a residue from the petroleum refining process, which contains a relatively highamount of high-molecular-weight PAHs.
In Japan, although there are currently no environmental standards or criteria for the regulation ofstanding stocks of PAHs in any environmental media, some PAHs, such as naphthalene,
methylnaphthalenes, and benzo[a]pyrene, are designated by the Ministry of the Environment as“compounds to be monitored” (2012) because of their adverse effects in aquatic organisms andhumans. Similarly, the US Environmental Protection Agency has designated 16 PAHs as priority
compounds to be monitored, seven of which are classified as carcinogenic compounds(benzo[a]anthracene,

benzo[a]pyrene,benzo[b]fluoranthene,

benzo[k]fluoranthene,chrysene,

dibenzo[a,h]anthracene, and indeno[1,2,3-cd]pyrene). In addition, 9 of the PAHs are also regarded as
potential mutagenic and teratogenic compounds (benzo[b]fluoranthene, benzo[a]anthracene,
benzo[a]pyrene,benzo[b]fluoranthene,

benzo[j]fluoranthene,

benzo[k]fluoranthene,chrysene,

dibenzo[a,h]anthracene, and benzo[ghi]perylene).
Since some PAHs, such as benzo[a]pyrene, are both carcinogenic and mutagenic, and theirconcentrations are occasionally high in sediment environments, the US National Oceanic andAtmospheric Administration has set sediment quality guidelines for PAHs by using effects range low(ERL) and effects range median (ERM) as indices of toxicity (Table 1). ERL and ERM mean theconcentrations of each PAH which can potentially give biologically adverse effect on aquatic biota at
10 and 50% of possibilities, respectively.

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Petroleum and Hydrocarbons

G1002EN-2

Table 1.

Effects range low (ERL) and effects range medium (ERM) of polycyclic aromatichydrocarbons (PAHs) in marine sediment (ng/g-dry sediment), NOAA (1999)

ERL

ERM

Acenaphthylene

44

640

Acenaphthene

16

500

Naphthalene

160

2100

2-Methylnaphthalene

70

670

Anthracene

85.3

1100

Phenanthrene

240

1500

Fluorene

19

540

Fluoranthene

600

5100

Pyrene665

2600

Benzo[a]anthracene

261

1600

Chrysene

384

2800

Benzo[a]pyrene

430

1600

Dibenzo[a,h]anthracene

63.4

260

Total PAH

4022

44792

Since there are no environmental criteria for PAHs in Japan, no regulatory monitoring for PAHs
has been conducted, as it has for dioxin and polychlorinated biphenyl. Thus, PAH monitoring data
have been collected only occasionally through governmental or academic monitoring activities(Horinouchi et al., 1999) and the only systematic data available are from fixed monitoring stations inharbor areas known to be polluted with terrigenous PAHs.
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Petroleum and Hydrocarbons

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The present manuscript describes the analytical methods used by the Ministry of the Environmentof Japan, the Japan Coast Guard, and local environmental organizations in Japan for the determinationof total hydrocarbon content and the amounts of individual PAHs and their alkylated derivatives inseawater and sediment.
2. Methods for the analysis of hydrocarbons in seawater and sediment2-1. Analysis of hydrocarbons in seawater (Integrated Global Ocean Services System; Report ofmarine pollution surveys, Japan Coast Guard)
A simple, widely employed method for analyzing the hydrocarbon content in seawater is themethod developed by the Integrated Global Ocean Services System (Figure 1). Briefly, 100 mL ofanalytical grade n-hexane is added to 2 L of sea water in a glass separatory funnel or bottle, and the
mixture is vigorously agitated by using a shaker or magnetic stirrer for 15 min. After agitation, themixture is left to stand until the seawater and hexane layers are distinctly separated. The upper hexane
layer is recovered; 80 mL of n-hexane is added to the residual seawater layer; and the agitation,
partitioning, and recovery process is repeated. The recovered hexane extracts are combined,
dehydrated with sufficient sodium sulfate anhydrous, and concentrated by using a rotary evaporator or
Kuderna–Danish concentrator. The volume of the concentrated hexane extract is adjusted to 10 mL
and then subjected to fluorescence spectrometry (emission wavelength, 360 nm; excitation wavelength,
310 nm). For quantification of any hydrocarbons in the hexane extract, a known concentration ofchrysene in n-hexane is used as the standard. The calculated values of samples as chrysene-equivalentconcentration should be multiplied by a factor of 6.7, if the calculated value is to be expressed as
petroleum-equivalent concentration.

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2 L of seawater(1) Add 100 ml of n-hexane
Agitation for 15 min.

Recover upper hexane layer (1)＋(2) Add 80 ml of n-hexane to bottom layer
Agitation for 15 min.

Recover upper hexane layer (2)Dehydration withsodium sulfate anhydrous
Condensation to 10 ml
Measurement by spectrofluorometer

Fig. 1 Flowchart of the Integrated Global Ocean Services System method for the analysis
of hydrocarbons in seawater samples.

2-2. Solvent extraction of sediment samples using n-hexane (Ministry of the Environment of Japan,
Analytical method for sediments, 2012)
n-Hexane extraction with gravimetric analysis is a method for determining the total hydrocarbon
content in sediment. This method is often used to determine the oil content in contaminated soils by
subjecting the obtained hexane extract to column chromatography using a column filled with Florisil®
powder, a synthetic magnesium silicate, to remove lipids and pigments such as chlorophyll producedby phytoplankton so that only the mineral oil content is analyzed. For marine environments used forcommercial fishing, the n-hexane extract should be less than 0.1% (weight/weight) (Water quality
criteria for fisheries (2018)).
In this method, 20 to 30 g of dried sediment is put into a glass-fiber extraction thimble andsubjected to Soxhlet extraction for 5 to 6 h with n-hexane as the extraction solvent. The hexane extract
is dehydrated with sufficient sodium sulfate anhydrous, and then the hexane is evaporated by heating
to 80°C to obtain a residue. The residue is weighed, and the weight is normalized to the dry weight ofthe sediment sample.
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Note that if the sample contains more sulfur particles than mineral oil, the sulfur particles can beco-extracted under reductive conditions, which can markedly influence the gravimetric measurement.
In that case, the sulfur can be removed by adding reduced copper granules to the hexane extract andallowing the mixture to stand overnight.
This extraction method can also be used to analyze seawater samples, and the resulting gravimetricconcentration is set as the water quality environmental standard in which “non-detectable” isconsidered as being compliant with the criteria (Ministry of the Environment, Japan).
2-3. Analysis of aliphatic hydrocarbons in sediment by using n-hexane extraction (Report of marine
pollution survey, Japan Coast Guard)
Figure 2 shows a flowchart of the quantitative analysis of aliphatic hydrocarbons in sediment by
n-hexane extraction. First, visible coarse materials such as gravel, shell, and pieces of animals andplants are removed from the sediment prior to analysis. Then, 40 to 50 g of wet sediment and 50 mL ofethanol containing 1 N potassium hydroxide are put into a glass centrifuge tube and heated under
reflux for 1 h. After cooling, 30 mL of n-hexane is added to the centrifuge tube, and the mixture isvigorously agitated and then centrifuged. After centrifugation, the mixture is allowed to stand until thehexane and ethanol layers have separated, and then the upper hexane layer is recovered into aseparatory funnel. The hexane extraction is repeated twice more times by adding 10 mL of n-hexane to
the remaining sediment each time, and the 3 recovered hexane layers are combined. Next, 50 mL ofpure water is added to the combined hexane extract, and the mixture is vigorously agitated and thenleft to stand until the hexane and water layers have separated. After partitioning, the hexane layer isrecovered and dehydrated with sufficient sodium sulfate anhydrous. The dehydrated hexane extract isconcentrated to approximately 1 mL and loaded onto a chromatography column filled with 3 g ofsilica gel (Wakogel S-1), 1 g of activated alumina, and 5 g of sodium sulfate anhydrous as the upper,
middle, and bottom layers of the column bed, respectively. The sample is eluted from the column with
100 mL of n-hexane; the first 20 mL of eluent is collected, and the hexane is completely evaporated toobtain a residue. The residue is dissolved in 5 to 20 mL of carbon tetrachloride and subjected to
Fourier transform infrared spectroscopy at 2930 cm−1. A known concentration of eicosane in carbon
tetrachloride is used as the standard for the quantification of aliphatic hydrocarbons in the sample.

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40 to 50 g (wet)of sediment
Add 50 ml of 1 M KOH/ethanol
Alkaline digestion for 1 hour with heating and condensation
Add 30 ml of n-hexane
shaking
Centrifugation

Bottom ethanol layerand sediment

Recover upper
hexane layer

Add 10 ml of n-hexane
shaking
Bottom ethanol layerand sedimentCentrifugation
Recover upper
hexane layer

Add 10 ml of n-hexane
shaking
Centrifugation
Bottom ethanol layerand sediment

Add 50 ml of pure water
Shaking and washing
Dehydration withsodium sulfate anhydrous
Condensation to 1 ml
Activated alumina silica gel column
Elution with 100 ml of n-hexane
Recover first 20 m1 eluent
Condensation and evaporation to dryness
Dissolve with 5 to 20 ml of carbon tetrachloride
Measurement by infrared spectrometer
Fig. 2 Flowchart of the analysis of aliphatic hydrocarbons in sediment by n-hexane extraction.

2-4. Analysis of individual aliphatic and aromatic hydrocarbons in sediment or biological tissue
Figure 3 shows a flowchart of the procedure for analyzing individual aliphatic and aromatichydrocarbons in sediment and biological samples.

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2-4a. Extraction and pretreatment
Extraction and pretreatment are conducted to extract aromatic and aliphatic hydrocarbons fromsediments and biological samples, to extract semi-volatile hydrocarbons directly from wet samples
without the need for drying, and to enable the simultaneous extraction of as many samples as possible.
This method minimizes the volume of organic solvents and the number of vessels used.
a.

Sediment sample: The inside of a glass centrifuge tube is rinsed with 50 mL of acetone, and thetube is left to dry. After drying, the tube is weighed before and after the addition of
approximately 3 g of wet sediment (with bulky material removed), and the exact weight of thesediment is calculated. Analytical grade acetone (7 mL) is added to the centrifuge tube, which isthen agitated vigorously with a vortex mixer, sonicated for 5 min, and centrifuged at 2500 rpm
for 5 min. After centrifugation, the clear acetone extract is transferred to a 50-mL glass
centrifuge tube by using a Pasteur pipette. Acetone (5 mL) is added to the remaining sediment,
the extraction is repeated, and the acetone extracts are combined.
Biological sample: 20 mL of 1 M potassium hydroxide in ethanol is added to homogenizedtissue in a 100-mL stoppered conical flask, and the resulting mixture is stirred for 15 h with amagnetic stirrer for alkaline digestion. After digestion, the mixture is transferred to a 50-mL
brown glass centrifuge tube.

b.

Analytical grade dichloromethane (DCM, 10 mL) is added to the sediment or biological tissue
remaining after extraction, and the mixture is agitated vigorously, sonicated for 5 min, andcentrifuged at 2500 rpm for 5 min. For a sediment sample, the DCM extract is combined withthe previous acetone extracts. For a biological sample, the DCM/ethanol extract is transferred toa 50-mL glass centrifuge tube.

c.

Ultrapure water (20 mL) is added to the combined extract, the mixture is agitated vigorouslywith a vortex mixer and centrifuged at 2500 rpm for 5 min, and the bottom organic solvent layer
is recovered and added to a glass funnel or syringe filled with 8 to 10 mL of sodium sulfate
anhydrous powder for dehydration; the dehydrated extract is received into a glass test tube.

d.

Steps b and c are repeated, but with the addition of only 7 mL of DCM in step b and without theaddition of water in step c. After recovery, step c is repeated once more with the addition of only
5 mL of DCM but without the addition of water.

e.

After 0.5 mL of n-decane and a predetermined volume (e.g., 10 µL) of analytical grade n-hexane
containing fixed concentrations (e.g., 50 µg/mL) of deuterated target PAHs (Table 2) are added
to the extract, the acetone and DCM are evaporated under a nitrogen stream with heating by ablock heater.

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Approximately 10 g (wet)of minced biological tissue

Approximately 3 g (dry)of sedimentA) Add 7 ml of acetone
and sonicate for 5 min.
CentrifugationA) First acetone extract

Precipitated residue
Add 20 ml of 1 M KOH/ethanol
Stirring for 15 hours＋

B) Add 5 ml of acetone
and sonicate for 5 min.
Centrifugation

B) Second acetone extract

Precipitated residue＋C) Add 10 ml of DCM
and sonicate for 5 min.
Centrifugation

C) DCM extract*

Precipitated residue

Add 20 ml of pure water tomixture of A), B) and C)
extracts* and mix well

Recover bottom layer
Dehydration and filtration＋D) Add 7 ml of DCM
and sonicate for 5 min.
Centrifugation

Add recovered D) DCM
extract to upper layer and mix

Recover bottom layer
Dehydration and filtration＋

Add recovered 5 ml of DCM
to upper layer and mix

Recover bottom layer
Dehydration and filtration

Add 0.5 ml of n-decane and deuterated PAHs
Condensation
Apply to silica gel column
Aliphatic hydrocarbons fraction is eluted
by addition of 1 ml of n-hexane three times
Aromatic hydrocarbons fraction is eluted
by addition of 1 ml of n-hexane with 5% acetone three times
GC-MS analysis

Fig. 3 Flowchart of the procedure for the analysis of individual aliphatic and aromatic hydrocarbons in
sediment and biological samples (*mixed ethanol extracts in the case of a biological sample).
2-4b. Fractionation of aliphatic and aromatic hydrocarbons by silica gel column chromatographya.

A chromatography column (volume, 3 mL) is filled with 0.5 g dry weight of activated silica gel(pre-packed columns are also commercially available) and connected to the vacuum manifold forsolid phase extraction via a stopcock. The column bed is washed with 3 mL of n-hexane with thecock under the column closed to keep the column bed submerged in the hexane.
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b. Fractionation of aliphatic hydrocarbons: The n-decane extract produced in 2-4a is passed throughthe column and received into a glass tube with scale marks. The tube originally containing then-decane extract is rinsed with 1 mL of n-hexane, and the rinse is passed through the column andinto the glass tube with scale marks. The rinsing procedure is repeated 2 more times or until thesurface of the n-hexane reaches the top of the silica gel bed. The n-hexane eluent is obtained as thealiphatic hydrocarbon fraction.
Fractionation of aromatic hydrocarbons: After elution of the aliphatic hydrocarbon fraction, theinside of the glass tube that originally contained the n-decane extract is rinsed with 3 mL ofn-hexane containing 5% (volume/volume) acetone, and the resulting rinse is passed through thesilica gel column bed into a brown 10-mL glass tube with scale marks; the rinsing process isrepeated 2 more times. The n-hexane eluent is obtained as the aromatic hydrocarbon fraction.
2-4c. Sampling and pretreatment of spilled oils and fuels
For the analysis of tarballs or oil paste washed up on beaches, samples are collected using a
stainless spatula and stored until analysis in a glass or metal container under dark, cool conditions to
avoid microbial and photo-degradation. If the tarball or oil paste cannot be sampled directly,
contaminated samples of sediments such as silt-clay, sand, and gravel are collected.
For batch extraction, the collected samples are transferred into individual glass beakers anddissolved in an appropriate volume of DCM. The DCM solutions are dehydrated with sufficientsodium sulfate anhydrous. To remove bulky, non-oily particles, the DCM solutions are filteredthrough a glass funnel plugged with defatted cotton soaked with DCM or are subjected to Soxhlet
extraction. The cleaned-up DCM solutions are then filtered through a polytetrafluoroethylene
membrane filter-cartridge (mesh size, 0.45 µm) connected to a glass syringe into pre-weighed glass
test tubes or flasks that can be connected to a rotary evaporator. Excess DCM is evaporated by using acentrifugal vacuum concentrator and a rotary evaporator, or by using a stream of nitrogen gas. Afterremoval of the DCM, the glass container containing the residue is weighed, and the net weight of theresidue is calculated by subtracting the weight of the empty glass container. The net weight of residue
is considered the ‘total solvent-extractable material’ weight, if all extracting processes described above
are quantitatively conducted.
For fine hydrocarbon analysis using a gas chromatograph, extracted oil samples are subjected tosilica gel column chromatography to remove non-volatile polar residues, which deteriorate thecapillary column, and to separate the aliphatic and aromatic hydrocarbon fractions. Extracted oilsamples are dissolved (suspended) in n-hexane, adjusted to 30 mg-oil paste/mL-hexane, and 5 mL of
the resulting solution is applied to the silica gel column (i.e., 15 mg of oil paste is loaded onto 1 g ofsilica gel column). The aliphatic and aromatic hydrocarbons are fractionated according to theprocedure described in 2-4b.

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2-4d. Target analytes (Wang et al., 1999)
Target analytes in the aliphatic hydrocarbon fractiona.

Normal alkanes (n-alkanes) with a carbon number of 12 to 40
Note: In many cases, only alkanes with a carbon number greater than 12 are detected fromweathered oil samples.

b.

Branched alkanes: Pristane and phytane
Biomarkers: 17αΗ, 21βΗ−hopane, 17βΗ, 21αΗ−hopane

Hopane is a triterpene contained in petroleum that is persistent to microbial and photo-degradation,
unlike aliphatic hydrocarbons and PAHs. Hopane is therefore used as a normalizer to evaluate thebiodegradation of petrogenic aliphatic hydrocarbons and PAHs in marine environments (Prince et al.,1994).
Target analytes in the aromatic hydrocarbon fraction

a. 2-ring PAHs: Naphthalene and its alkylated derivatives (carbon number: 1–4)
b. 3-ring PAHs: Fluorene and its alkylated derivatives (carbon number: 1–2), dibenzothiophene
and its alkylated derivatives (carbon number: 1–3), phenanthrene and its alkylated derivatives(carbon number: 1–3), acenaphthylene, acenaphthene, anthracenec. 4-ring PAHs: Pyrene, fluoranthene, chrysene, benzo[a]anthracened. 5-ring PAHs: Benzo[e]pyrene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene,
dibenzo[a,h]anthracenee. 6-ring PAHs: Benzo[ghi]perylene, indeno[1,2,3-cd]perylene
2-4e. Analytical conditions for gas chromatography (Ministry of the Environment of Japan,
Analytical method for sediments, 2012)
Gas chromatography equipped with mass spectrometry (GC-MS) is suitable for the analysis ofevery semi-volatile aliphatic and aromatic hydrocarbons. For the analysis of linear and branchedalkanes, gas chromatography with flame ionization detector (GC-FID) is also available.


Column (capillary type): Semi-polar type, such as HP-5, DB-5, Ultra-2, and SPB-5, withliquid phase thickness 0.25 µm, inner diameter 0.25 mm, and length 30 m

Sample injection: Splitless mode, sampling time 30 to 90 s until purge, temperature 280 to
300 °C, sample injection volume 1 µL

Temperature programa. Alkanes and biomarkers: 50 °C for 2 min, increase to 300 °C at 6 °C/min, hold at
300 °C for 15 minb. PAHs: 50 °C for 2 min, increase to 120 °C at 20 °C/min, increase to 270 °C at
7 °C/min, increase to 320 °C at 20 °C/min, hold at 300 °C for 15 minCarrier gas: High-purity helium gas is used for both GC-FID and GC-MS. High-purity
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nitrogen gas can be also used for GC-FID but not for GC-MS.


Carrier gas flow rate: 1 to 2 mL/min

Detector temperature: 300 °C for FID; 230 to 300 °C for the interface between GC and MS

Detection mode for GC-MS: Selected ion monitoring modeQualification and quantification

Figure 4a shows representative mass chromatograms of alkylated PAHs in extracts of seabedsediment, demonstrating that petrogenic PAHs exist as a complex mixture of isomers and homologues,
which means that standard reagents for these PAHs are not commercially available. Therefore,
pre-analysis of the aromatic hydrocarbon fraction of oil samples by GC-MS in scan mode is needed toverify the retention time of each alkylated PAH isomer and homologue for setting the selected ion
monitoring mode time program. For undetected and/or unidentified PAH peaks in the aromatichydrocarbon fraction, commercial standard compounds should be pre-analyzed by GC-MS in scanmode to verify the retention time of each of their peaks.

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Table 2.

Monitor and reference ions for select hydrocarbons analyzed by gas chromatography withmass spectrometry

Analytes and surrogates

Monitor ion (m/z)

Reference ion (m/z)

Linear n-alkanes

71

85

Branched alkanes

71

85

Biomarkers

191

Acenaphthene

153

Acenaphthene-d10

164

Acenaphthylene

152

Acenaphthylene-d10

160

Naphthalene

128

Naphthalene-d8

136

C1-Naphthalene

142

115

C2-Naphthalene

156

141

C3-Naphthalene

170

C4-Naphthalene

184

Fluorene

166

Fluorene-d10

176

C1-Fluorene

180

C2-Fluorene

194

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102

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Dibenzothiophene

184

C1-Dibenzothiophene

198

C2-Dibenzothiophene

212

C3-Dibenzothiophene

226

Anthracene, phenanthrene

178

Phenanthrene-d10, anthracene-d10

188

C1-Phenanthrene

192

C2-Phenanthrene

206

C3-Phenanthrene

220

Pyrene, fluoranthene

202

Pyrene-d10, fluoranthene-d10

212

Chrysene, benzo[a]anthracene

228

Chrysene-d12

240

139

152

101

114

Benzo[e]pyrene, benzo[a]pyrene,
252

126

benzo[b]fluoranthene, benzo[k]fluoranthene
Benzo[k]fluoranthene-d12,
264
benzo[a]pyrene-d12, benzo[e]pyrene-d12
Dibenzo[a,h]anthracene

278

Dibenzo[a,h]anthracene-d14

292

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Benzo[ghi]perylene,
276

138

Indeno[1,2,3-cd]perylene
Benzo[ghi]perylene-d12

288Terphenyl-d14

244

Alkanes and biomarkers are quantified by using deuterated p-terphenyl (p-terphenyl-d14) as theinternal standard. The ratio of the alkane or biomarker peak area (Ax) to that of p-terphenyl-d14 (Ais) is
calculated by co-injecting a mixture with known concentrations of each alkane or biomarker andp-terphenyl-d14 into the GC-MS system. Standard curves are created by plotting Ax/Ais versus the ratioof a stepwise increase in the concentration of each alkane or biomarker (Cx) to a constantconcentration of p-terphenyl-d14 (Cis) as the vertical and horizontal axes, respectively. The
concentration of each alkane or biomarker in the sample is then calculated by multiplying Cis by theCx/Cis corresponding to the Ax/Ais in the previously created standard curve. Ax/Ais is obtained byco-injecting a known concentration of p-terphenyl-d14 into the GC-MS system.
For the quantification of PAHs, standard curves are created by plotting the ratio of peak area
versus the ratio of the concentration of each non-deuterated PAH to its corresponding deuterated PAH(Table 2), instead of p-terphenyl-d14, as the internal standard. For the quantification of alkylated PAHs,
standard curves are created by plotting the ratio of peak area versus the ratio of the concentration of
the non-deuterated alkylated PAH to that of the corresponding deuterated non-alkylated PAH (Table3) because deuterated alkylated PAHs are rarely commercially available. The concentration of each
non-alkylated and alkylated PAH is calculated as described for alkanes and biomarkers, except thecompounds are used as the internal standard instead of p-terphenyl-d14. The recovery efficiency foreach PAH is calculated by spiking the sample with a known concentration of the corresponding
deuterated PAH before extraction and is checked to confirm that it is within the allowable range(70%–130%).
Finally, the concentration of each hydrocarbon is evaluated as a value normalized by dry weight of
sediment, dry or wet weight of biological sample, or the total solvent-extractable material of oilsample.

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Table 3.

Commercially available standards and substitutes of alkylated polycyclic aromatichydrocarbons (PAHs)

Target alkylated PAH

Corresponding standard or substituteC1-Naphthalene

1-Methylnaphthalene, 2-methylnaphthalene

C2-Naphthalene

2,6-Dimethylnaphthalene

C3-Naphthalene

2,3,5-Trimethylnaphthalene

C4-Naphthalene

2,3,5-Trimethylnaphthalene

C1-Fluorene

1-Methylfluorene

C2-Fluorene

1-Methylfluorene

C1-Dibenzothiophene

4-Methyldibenzothiophene

C2-Dibenzothiophene

4,6-Dimethyldibenzothiophene

C3-Dibenzothiophene

4,6-Dimethyldibenzothiophene

C1-Phenanthrene

1-Methylphenanthrene,
2-Methylphenanthrene,
3-Methylphenanthrene,
9-Methylphenanthrene

C2-Phenanthrene

3,6-Dimethylphenanthrene

C3-Phenanthrene

3,6-Dimethylphenanthrene

2-4f. Example analysis of real-world samples and accompanying remarks
Figure 4a shows mass chromatograms of alkylated PAHs in extract obtained from the seabed in abay in the Tohoku region of Japan that was contaminated with spilled oil. The mass chromatograms
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contain many vicinal peaks with the same m/z and very similar peak patterns, showing that the extractcontained many isomers of alkylated PAHs. Petrogenic alkylated PAHs are more easily biodegraded
than petrogenic high-molecular-weight PAHs such as pyrene, fluoranthene, and chrysene; therefore,
alkylated PAHs are less persistent in the environment than PAHs with 4 or more rings (Maki et al.,2003).

Fig. 4a Mass chromatograms of alkylated polycyclic aromatic hydrocarbons in extract
obtained from a contaminated seabed.
a-1: C2-naphthalenes (m/z 156); a-2: C3-naphthalenes (m/z 170); a-3: C4-naphthalenes(m/z 184); b-1: C1-dibenzothiophenes (m/z 198); b-2: C2-dibenzothiophenes (m/z 212); b-3:
C3-dibenzothiophenes (m/z 226); c-1: C2-phenanthrenes (m/z 206); c-2: C3-phenanthrenes (m/z220); d-1: C1-fluorenes (m/z 180); d-2: C2-fluorenes (m/z 194).

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e-1

a

e-2

e-3

e-4

e

Fig. 4b Mass chromatograms of 5- and 6-rings polycyclic aromatic hydrocarbons in theextract shown in Fig. 4a.
e-1: Benzo[e]pyrene (dotted ellipse e) (m/z 252), benzo[a]pyrene (a) (m/z 252); e-2:
indeno[1,2,3-cd]perylene (dotted ellipse) (m/z 276); e-3: dibenzo[a,h]anthracene (dotted
ellipse) (m/z 292); e-4: benzo[ghi]perylene (dotted ellipse) (m/z 276).

Figure 4b shows mass chromatograms of the high-molecular-weight PAHs with 5 or 6 rings
detected in the extract shown in Figure 4a. The presence of fake peaks next to the peak of the target
PAH with the same m/z means that the retention time of each peak must be verified by referencing
those of PAH standards. Note that the peaks corresponding to benzo[e]pyrene, benzo[a]pyrene, andbenzo[ghi]perylene should be carefully identified because they sequentially emerge on the mass

chromatogram with a m/z of 252 and a relatively short retention time. Similarly, the peaks ofbenzo[b]fluoranthene and benzo[k]fluoranthene cannot be easily resolved on mass chromatogram as
they also have an m/z of 252.

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Fig. 5 Mass chromatograms at m/z 71 showing the alkanes in various oils and sediments.
(1) Crude oil spilled by the 2011 Tohoku earthquake and tsunami; (2) heavy fuel used in thermal
power stations; (3) heavy fuel used by ships; (4) sediment collected from a bay polluted with heavy
fuel spilled by the 2011 Tohoku earthquake and tsunami; (5) sediment collected from a bay notpolluted by the 2011 Tohoku earthquake and tsunami. The number above each peak indicates thenumber of carbon atoms in the alkane; “pri” and “phy” indicate the peak of the branched alkanes
pristane and phytane, respectively.

As described above, trace levels of high-molecular-weight PAHs with more than 5 or more rings
are detected in Arabic crude oil. However, some heavy fuels, such as that spilled from the wrecked
Russian tanker Nakhodka in the Sea of Japan in 1997, contain high amounts of high-molecular-weight
PAHs (Horinouchi et al., 1999; Maki et al., 2003). GC-detectable hydrocarbons constitute less than
10% of the total compounds in any crude oil sample (Wang et al., 1999). The major compounds incrude oil remain to be identified.
Since low-molecular-weight n-alkanes with a carbon number less than 12 are volatile andhigh-molecular-weight n-alkanes with a carbon number of more than 12 are subject to microbial
degradation in a short period of time, n-alkanes are usually not abundantly detected in environmental
samples. However, since unweathered oils and fuels contain abundant amounts of semi- andnon-volatile n-alkanes, the gas chromatograms of unweathered oils and fuels are characterized by aregular array of peaks for a series of n-alkanes that increases by one carbon number for each peak (Fig.
5 (1)–(3)). The peaks immediately after C17 (heptadecane) and C18 (octadecane) represent the
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branched alkanes pristane and phytane, respectively, and are characteristic peaks in mass
chromatograms of petroleum samples. Since these branched alkanes degrade more slowly thann-alkanes, the pristane or phytane to n-alkane ratio increases as oil is more weathered.
Figure 5 (5) shows the mass chromatogram of the alkanes in the extract obtained from a sample ofnon-polluted seabed. The high amounts of alkanes with a high, odd carbon number indicate that thealkanes originated from the wax of terrestrial plants (Wang et al., 1999).
References
Analytical method for sediments http://www.env.go.jp/water/teishitsu-chousa/ (2012): Ministry of theEnvironment, Japan. (in Japanese).
Horinouchi A., S. Tsutsumi, E. Kouno, H. Takada, P. M. Zakaria and S. Noriki (1999): Chemical
characterization of petroleum using GC-MS and behaviors and effects of hydrocarbons in the environments(Symposium: present status and future subjects of researches on petroleum pollution) Bulletin on Coastal
Oceanography, 37, 23−34. (in Japanese).
Maki, H., M. Utsumi, H. Koshikawa, T. Hiwatari, K. Kohata, H. Uchiyama, M. Suzuki, T. Noguchi, T.
Yamasaki, M. Furuki, and M. Watanabe (2003): Intrinsic biodegradation of heavy oil from Nakhodka andthe effect of exogenous fertilization at a coastal area of the Sea of Japan. Water Air Soil Pollut., 145,
123–138.
Prince, R. C., D. L. Eimendorf, J. R. Lute, C. S. Hsu, C. E. Haith, J. D. Senius, G. J. Dechert, G. S. Douglas, andE. L. Butler (1994): 17α(H),21β(H)-hopane as a conserved internal marker for estimating the biodegradationof crude oil. Environ. Sci. Technol., 28, 142–145.
Report of marine pollution surveys, Hydrographic and Oceanographic Department, Japan Coast Guard. (inJapanese).
Sediment

qualityguidelines

developed

for

the

national

statusandtrendsprogram

http://ccma.nos.noaa.gov/publications/sqg.pdf (1999): NOAA, USA.
Wang, Z., M. Fingas, and D. Page (1999): Oil spill identification. J. Chromatogr. A., 843, 369–411.
Water quality criteria for fisheries (2018): Japan Fisheries Resource Conservation Association. (in Japanese).

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Petroleum and Hydrocarbons

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G1003EN-1

Microplastics (Surface Water Trawl Surveys for Small Debris Items)‫ۑ‬Takashi MIYAO (Japan Meteorological Agency)

1.

Introduction
Plastic debris in the marine environment has significant impacts on marine ecosystem, and is oneof the major global issues. Although small plastic debris is generally undetectable with shipboard
sighting survey, there is no doubt that they have been steadily increasing within marine environment inspite of efforts to control the problem (UNEP, 2014). Moreover, it has been revealed that marine
plastics carry toxic chemicals of smaller molecular size (MW < 1000), which can penetrate throughthe cell membrane (Takada et al., 2009; Teuten et al., 2009). There is evidence that plastics are
fragmenting in the marine environment (Barnes et al., 2009), as a consequence, small fragments ofplastics are distributed throughout the ocean, occurring on shorelines, in surface waters, seabedsediments from Arctic to Antarctic and in a wide variety of biota such as invertebrates, fish, seabirds,
mammals etc. (Ryan et al., 2009; Reisser et al., 2014).
The term “microplastics” was introduced in mid-2000s, and are used pragmatically to describe
plastic particles “smaller than 5mm” (Arthur et al., 2009; GESAMP, 2015). Microplastics are often
classified into two main categories: (i) “primary” microplastics are originally manufactured to be of a
microscopic size for particular industrial or domestic applications, and (ii) “secondary” microplastics
are tiny plastic fragments derived from the breakdown of larger plastic debris, both at sea and on land(Cole et al., 2011).
In this chapter, the methodology of the surface water trawl surveys for small size debris, mainly
microplastics, is described. Trawl surveys are less subjective than direct sighting survey (Ryan et al,2009), but currently no universally accepted standard method is available for observations of
microplastics. Therefore, the following is only suggested procedures derived from many previous
reports.
Incidentally, examinations of stomach contents of seabirds and sea turtles can also bringinformation about microplastics; however, they need quite another technique and equipment.
2.

Objectives and Setting of Surveys

2-1 Objectives

Shipboard surface water trawl surveys obtain samples of floating microplastics and collectinformation on their distribution, types and amounts. Typical objectives for open-water trawlingsurveys are, for example, as follows:- to obtain samples of microplastics;- to identify types of microplastics;- to estimate concentration of microplastics;- to detect temporal and spatial variation in the occurrence of microplastics.
It is desirable that trawl surveys are accompanied with direct sighting survey for floating pollutants
Guideline of ocean observations Vol. 10 Chap. 3 © Takashi MIYAO 2016 G1003EN:001-009

G1003EN-2(see Chapter 4) in order to interpret the connection with the distribution of larger debris. While fieldsampling and sample processing, avoid wearing clothes made of polymer or synthetic fibers, because
they may contaminate plastic samples. Woodall et al. (2015) gave more strict information on thecontamination of the samples.
2-2 Site Selection

There has been little information about abundance and types of floating microplastics, as well as
about larger pollutants, in the open-ocean. The survey sites should be selected in consideration of thefollowing matters:

to deliberate on sources and transportation process affected by the wind system and the major
currents;to focus on areas that are known to accumulate pollutants;

 not to impact on marine ecosystems by the navigation of the observation ship.
For example, the area of concentrated small debris, known as “Great Pacific Garbage Patch”, lies
off the Japan Archipelago and between Hawaii and California, almost coincident with the Subtropical
Convergence Zone, affected by Ekman dynamics (Dautel, 2009; EPA, 2011). Isobe et al. (2014)
described that they sought oceanic fronts before trawl survey, because floating plastic debris is likely
to be trapped there. Needless to say, sampling site should not be located close to shore and considered
to be shallow, taking the dimension of observation ship into account.
2-3 Frequency and Timing of Surveys

For long-standing monitoring in fixed region, the minimum sampling frequency should beannually. Ideally quarterly sampling is recommended, allowing an interpretation on seasonal changes.
It is well known that depth profiles of microplastics are mainly affected by turbulence in thesurface layer; especially smaller particles are more susceptible to vertical transport (Kukulka et al.,2012; Reisser et al., 2015). Therefore, it is desirable that trawl surveys for microplastics floating
within thin surface layer are conducted under calm sea state as far as possible.
3.

Shipboard Trawl Survey

3-1 Outline of Sampling Method

Surface water trawl surveys are conducted in the daytime, so that the state of sampling net can beseen clearly. Sampling net attached to the end of the towrope is deployed while the ship is moving atconstant speed, and trawled for preset time duration (details will be described later). During the trawl,
towrope length may be adjusted to ensure approximately half of net mouth is under water, so thatsampling net skims the sea surface. In order to stabilize sampling net posture, weights can be attachedat the bottom of net mouth frame, or floats can be put on both sides of the net mouth. Sampling net
should be placed on a boom, if possible, in order to avoid the wake behind the ship.
After sampling net is recovered, filtered surface water sample is collected in small net bag in theend bucket (traditionally called “cod-end”), washing gently with natural seawater from the outside of

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G1003EN-3

the sampling net. Next, the end bucket is detached and entire contents of small net bag are transferred
into another container, rinsing with natural seawater or fresh water. Extra care must be taken because
small items are easily lost under rainy or windy condition.
The sample may be consequently processed on shipboard or stored in labeled container forlaboratory processing (see 3-4). In the latter case, sample should be frozen or chemically preserved(add formalin etc.) as soon as possible not to turn putrid. Note that the chemically preserved samples
generally cannot be submitted for persistent organic pollutants (POPs: such as PCBs, DDTs etc.)
analysis.
3-2 Equipment

The observation ship should equip GPS unit for determination of ship position and speed
continuously. Appropriate trawling system (crane, winch, capstan etc.) and sampling net with supplies(cable/rope, shackles, swivels etc.) are required for net-based surveys.
Although many kinds of sampling nets are available for trawl surveys, among them neuston net
and manta net, shown in Figure 3-1, seem to have been most frequently used (Ribic et al., 1992; Lattin
et al., 2004; Ryan et al., 2009; Lippiatt et al., 2013; Reisser et al., 2013; Isobe et al., 2014). Both ofthem are implements for sea surface sampling, the latter is supposed to resemble a manta ray, withmetal wings and broad rectangular mouth.

Figure 3-1 Neuston net (left; [http://www.aoml.noaa.gov/ocd/ocdweb/waltonsmith_photos.html]) and manta net (right; Masura et al., 2015).

Desforges et al. (2014) collected subsurface water sample (4.5m below the water line) using thesaltwater intake system of the vessel. Although their sampling method is independent on sea state andneeds no trawling system on the vessel, the plastic concentration in subsurface water is generally
lower than the surface water. Consequently, it is likely that total amount of microplastics in the watercolumn may be underestimated.

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G1003EN-4

4.

Sample Processing
Microplastics in surface water samples are often classified by their size, external characteristics(function of the original product) and polymer types. Efforts of classification are important as obtained
information can be used to pinpoint sources of plastic debris and target reduction measures.
4-1 Sieving and Visual Separation

First, any obvious large debris items, larger than centimeter-sizes, are manually removed fromsurface water samples. Consequently, samples are filtered through double-stacked sieves, which haveequivalent mesh size of upper and lower limit size of target microplastics (Masura et al. (2015) used
5.6-mm (No. 3.5) and 0.3-mm (No. 50)), to separate debris into two size fractions, and rinsed with
distilled water. Material retained on the upper limit size sieve can be discarded or archived for anotherstudies. The sample collected on the lower limit size sieve is transferred into some other container.
Next, plastic fragments are visually (by naked eye or with the aid of magnifier/microscope)
identified and picked up and placed in a graduated petri dish with forceps or some adequate instrumentfrom the sample. This is an almost obligatory step to separate plastics from other materials, such asorganic debris, small pieces of hull-originated paint, metal, glass, etc., and, if possible, should be
confirmed by more than one people for quality assurance (Lippiatt, et al., 2013). Plastic fragments on
the petri dish can be counted for every different size categories, and can be weighed after drying
process. Pre-weighed vials or dishes are useful for the procedures described here.
4-2 Classification by External Characteristics

Microplastics can be classified by external characteristics into several types. For example, Erikson(2005) introduced seven types: i) Pellet, ii) Fragment, iii) Film – plastic debris of bags or wrappers, iv)
Foam, v) Filament, vi) Cigarette parts and vii) Other debris (including glass, rubber, metal, etc.).
Lattin et al. (2004) sorted plastics into six categories – i) fragments, ii) styrofoam, iii) pellets, iv)
polypropylene/monofilament line, v) thin plastic films and vi) resins. UNEP/IOC (2009) also showed
the detail “standard categories” for remote benthic and floating observation, including seven classes; i)Containers, ii) Fishing & Boating, iii) Food and Beverage, iv) Packing, v) Sanitary, vi) Smoking andvii) Other.
4-3 Density Separation

Although many different types of plastics are produced globally, 6 classes are dominant in themarket (GESAMP, 2015) and given “SPI Resin Identification Code” (see American ChemistryCouncil, 2007) as follows: i) polyethylene terephthalate (PET), ii) high-density polyethylene (HDPE),iii) polyvinyl chloride (PVC), iv) low-density polyethylene (LDPE), v) polypropylene (PP), vi)
polystyrene (PS, including expanded polystyrene EPS) and vii) others. Their code and density data fortypical virgin resins are summarized in Table 3-1.

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G1003EN-5

Table 3-1. SPI Resin Identification Code and Plastic Classes (American Chemistry Council, 2007) withdensity data (Eriksen, 2005).

Code
1
2
3
4
5
6
7

Plastic ClassPETPolyethylene terephthalate
HDPE
High-density Polyethylene
PVC
Polyvinyl Chloride
LDPE
Low-density Polyethylene
PP
Polypropylene
PS
Polystyrene(Others) Cellulose Acetate etc.

Density#[g ή cmିଷ ]1.38 – 1.39
0.95 – 0.97
1.16 – 1.35
0.92 – 0.94
0.90 – 0.91
1.05 – 1.07-

# Densities given here are approximate value for typical virgin resins. Note that plastic products are often
mixed with fillers and additives that may alter their density.

The plastic fragments can be separated based on the difference of densities among plastic classes(Corcoran, 2009). Plastics that float in seawater and fresh water are EPS, high and low density PE, and336ROLGIRUP36DOVRIORDWVLQDVDWXUDWHG1D&OVROXWLRQ ȡ؆>JÂFP-3]). Plastics that finally float in
sodium polytungstate solution include flexible/rigid PVCs and PETs. As the density of 30% CaCl2
solution is approximately equal to 1.3 >JÂFP-3], it can be used to separate PET and PVC. Ethanol-water
PL[WXUHVRIYDULRXVGHQVLWLHVLQFOXGLQJȡ  0.9408 and 0.911 >JÂFP-3], can be used to separate PS,
high and low density PE and PP. Cooking oils, their densities are approximately equal toethanol-water mixtures, may also be used for plastic separation (Eriksen, 2005).
4-4 Spectroscopic Identification

There are some concern that density separation method may make misidentification, because thedensity of plastic fragments may vary considerably depending not only on the polymer type, but also
on the manufacturing process, fillers and additives. For that reason, use of spectroscopic method(FT-IR spectroscopy, near-infrared spectroscopy, Raman spectroscopy etc.) is recommended, because
it may bring certain determination of the polymer types of plastic samples (Hidalgo-Ruz et al., 2012).
If plastic samples are not submitted for chemical analysis of PCBs, DDTs etc., they should be
disposed appropriately.
5.

Variables to Consider

5-1 Weather Condition and Sea StateAs mentioned above, depth profiles of microplastics are mainly affected by turbulence in thesurface layer. If the sea surface is choppy, net mouth might be submerged and/or be out of the water,and sampling net will not collect “surface water sample”. Trawl surveys should not be conducted instrong wind and rough sea surface condition. It is also recommended to avoid the area where tide
and/or current may be strong.

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G1003EN-6

5-2 Ship Speed and Time Duration

Trawl surveys should be conducted at a ship speed of 1-3 knots, if there is interest to size
distribution of microplastics. In recent studies, trawling speed are usually 2-4 knots Lattin et al., 2004;
UNEP/IOC, 2009; Reisser et al., 2013; Isobe et al., 2014㸧, if the ship speed is too fast, objects
collected in sampling net may be increasingly susceptible to fragmentation resulting from abrasion,
wave-action and turbulence (Cole et al., 2011).
Time duration of the trawl shot depends on the ship speed, and should be set supposing the amountof floating objects; however, as often conducted in neuston study, every trawl shot should be made forat least 10 minutes.
5-3 Mesh Size of Sampling Net

It is a natural consequence that the minimum size of debris collected by sampling net depends on
its mesh VL]H7KHPDMRULW\RIVDPSOLQJQHWVXVHGLQUHFHQWVWXGLHVKDYHDPHVKVL]HRIDURXQGȝP
)RUH[DPSOH5LELFHWDO  UHFRPPHQGHGȝP-mesh net. In “NOAA Marine Debris Program”,/LSLDWW HW DO   DQG 0DVXUD HW DO   LQWURGXFHG WKH  ȝP-PHVK DQG  ȝP-mesh net,respectively. Isobe et al. (2014) used neuston net with mesh size of 0.35mm. Therefore, recommended
PHVKVL]HRIVDPSOLQJQHWVLVDURXQGȝPLQWKLVJXLGDQFH$OOWKHSDUWLFOHVVPDOOHUWKDQWKHPHVKsize go through sampling net.
5-4 Personnel

Required personnel include technical experts, who are experienced in or trained in the use ofsampling net and visual separation.
6.

Data and Metadata

6-1 Classification of Microplastics

As mentioned in 3-4-2, microplastics can be classified by external characteristics. Their color,shape, dimension (length/width), wear etc. may be close observed and recorded. Microplastics can becounted and weighed for every different size categories or polymer types. Although there is nouniversally authorized classification of microplastics has, it should be decided based upon previous
works, depending on observation purpose.
6-2 Concentration of Microplastics

For quantitative comparisons of different surveys, it is strongly recommended that concentration of
PLFURSODVWLFV VKRXOG EH UHSRUWHG LQ HLWKHU XQLW DPRQJ QH[W RQHV >LWHPVÂNP-2@ >LWHPVÂP-3] and>PJÂP-3].
Sea surface area skimmed by sampling net can be calculated multiplying net mouth width by trawl
shot length. Consequently, water volume passed through the sampling net can be estimated from thearea found above and net mouth height under water. To measure water volume directly and more
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G1003EN-7

exactly, sampling net should be equipped with a flowmeter, calibrated under the calm sea surface
condition, at the net mouth (e.g. Lippiatt et al., 2013; Isobe et al., 2014).
6-3 Metadata

Metadata should include following information:

7.

Survey name, date, time, location



Ship characteristics: Name, type (e.g. research, fishing, regular ferry etc.), tonnage, length,
width etc.

Detail of trawl shot: latitude/longitude of start/end point, trawl shot length, ship speed, time
duration

Detail of sampling net: Type, dimension (net mouth width and height), mesh sizeEnvironmental conditions: wind speed/direction, wave and swell (direction/height/period),surface current etc.

Concluding Remarks
Surface water trawling survey can provide valuable information on the concentration and types of

microplastics. From results of previous trawl surveys, however, variability in amounts of microplastics
may be considerably large. Therefore, increase of sample water volume or number of trawl surveys
will be expected for a given level of confidence. Careful consideration to survey design andstandardization should be paid in order to develop robust estimates of concentration of microplastics.
References
American Chemistry Council (2007): Plastic Packaging Resins (SPI Resin Identification Code). Retrieved from[http://plastics.americanchemistry.com/Education-Resources/Plastics-101/Plastics-Resin-Codes-PDF.pdf](2015/07/22).
Arthur, C., J. Baker, H. Bamford, N. Barnea, R. Lohmann, K. McElwee, C. Morishige and R. Thompson (2009):
Summary of the International Research Workshop on the Occurrence, Effects, and Fate of Microplastic
Marine Debris. In Proceedings of the International Research Workshop on the Occurrence, Effects, and Fateof Microplastic Marine Debris. Sept 9-11, 2008. NOAA Technical Memorandum NOS-OR&R-30.
Barnes, D. K. A., F. Galgani, R. C. Thompson and M. Barlaz (2009): Accumulation and fragmentation of plastic
debris in global environments. Philosophical Transactions of the Royal Society. B364, 1985–1998.
Cole, M., P. Lindeque, C. Halsband, and T. S. Galloway (2011): Microplastics as contaminants in the marine
environment: A review. Marine Pollution Bulletin, 62, 2588–2597.
Corcoran, P. L., M. C. Biesinger and M. Grifi (2009): Plastics and beaches: A degrading relationship. Marine
Pollution Bulletin, 58, 80–84.
Dautel, S. L. (2009): Transoceanic Trash: International and United States Strategies For the Great PacificGarbage Patch, Golden Gate University Environmental Law Journal, 3, 181-208.
Desforges, J-P. W., M. Galbraith, N. Dangerfield and P. S. Ross (2014): Widespread distribution of
microplastics in subsurface seawater in the NE Pacific Ocean. Marine Pollution Bulletin, 79, 94-99.

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EPA (2011): Marine Debris in the North Pacific: A Summary of Existing Information and Identification of Data
Gaps. United States Environmental Protection Agency. 23pp.
Eriksen, M. (2005): Watershed Wonders: Standard Based Activities and Information about Water andWatersheds for Middle and High School Classrooms. Algalita Marine Research Foundation, 91pp. Retrieved
from [http://people.oregonstate.edu/~rochefow/K-12 Outreach Activities/SKIES curriculum/SKIES Ecology
and Environmental Engineering/WatershedWonders-curr.pdf] (2015/07/22).
GESAMP (2015): Sources, Fate and Effects of Microplastics in the Marine

Environment:

A Global

Assessment (Kershaw, P. J., ed). IMO/FAO/UNESCO-IOC/UNIDO/WMO/IAEA/UN/UNEP/UNDP Joint
Group of Experts on the Scientific Aspects of Marine Environmental Protection. GESAMP Reports &Studies Series, No. 90, 96pp.
Hidalgo-Ruz, V., L. Gutow, R. C. Thompson, M. Thiel (2012): Microplastics in the Marine Environment: A
review of the Methods Used for Identification and Quantification.
Environmental Science & Technology, 46, 3060–3075.
Isobe, A., K. Kubo, Y. Tamura, S. Kako, E. Nakashima and N. Fujii (2014): Selective transport of microplastics and mesoplastics by drifting in coastal waters. Marine Pollution Bulletin, 89, 324-330.
Kukulka,T., G. Proskurowski, S. Morét-Ferguson, D. W. Meyer and K. L. Law (2012): The
effect of wind mixing on the vertical distribution of buoyant plastic debris. Geophys. Res. Lett., 39, L07601,
doi:10.1029/2012GL051116.
Lattin, G. L., C. J. Moore, A. F. Zellers, S. L. Moore and S. B. Weisberg (2004): A comparison of neustonic
plastic and zooplankton at different depths near the southern California shore. Marine Pollution Bulletin, 49,
291-294.
Lippiatt, S., S. Opfer, and C. Arthur (2013): Marine Debris Monitoring and Assessment. NOAA Technical
Memorandum NOS-OR&R-46.
Masura, J., J. Baker, G. Foster and C. Arthur (2015): Laboratory methods for the analysis of microplastics in themarine environment: recommendations for quantifying synthetic particles in waters and sediments. NOAA
Technical Memorandum NOS-OR&R-48.
Reisser, J., J. Shaw, C. Wilcox, B. D. Hardesty, M. Proietti, M. Thums and C. Pattiaratchi(2013): Marine Plastic Pollution in Waters around Australia: Characteristics, Concentrations, and Pathways. PLoS ONE 8, e80466, doi:10.1371/journal.pone.0080466.
Reisser J., J. Shaw, G. Hallegraeff, M. Proietti, D. K. A. Barnes, M. Thums , C. Wilcox, B. D. Hardesty and C.
Pattiaratchi (2014): Millimeter-Sized Marine Plastics: A New
Pelagic Habitat for Microorganisms and Invertebrates. PloS ONE9, e100289, doi:10.
1371/journal.pone.0100289.
Reisser, J. , B. Slat, K. Noble, K. du Plessis, M. Epp, M. Proietti, J. de Sonneville, T. Becker and C. Pattiaratchi(2015): The vertical distribution of buoyant plastics at sea: an ob-servational study in the North Atlantic Gyre.
Biogeosciences, 12, 1249–1256, www.
biogeosciences.net/12/1249/2015/, doi:10.5194/bg-12-1249-2015
Ribic, C. A., T. R. Dixon, and I. Vining (1992): Marine Debris Survey Manual. NOAA Technical Report NMFS
108.

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Ryan, P. G., C. J. Moore, J.A. van Franeker and C. L. Moloney (2009): Monitoring the abundance of plastic
debris in the marine environment. Philosophical Transactions of the RoyalSociety B: Biological Sciences
364, 1999–2012.
Takada, H., Y. Mato, S. Endo, R. Yamashita and M. P. Zakaria (2009): Pellet Watch: Global Monitoring of
Persistent Organic Pollutants (POPs) using Beached Plastic Resin Pellets. In Proceedings of the International
Research Workshop on the Occurrence, Effects, and Fate of Microplastic Marine Debris. Sept 9-11, 2008.
NOAA Technical Memorandum NOS-OR&R-30.
Teuten, E. L., J. M. Saquing, D. R. U. Knappe, M. A. Barlaz, S Jonsson, A. Björn, S. J. Rowland, R. C.
Thompson, T. S. Galloway, R. Yamashita, D. Ochi, Y. Watanuki, C. Moore, P. H. Viet, T. S. Tana, M.
Prudente, R. Boonyatumanond, M. P. Zakaria, K. Akkhavong, Y. Ogata, H. Hirai, S. Iwasa, K. Mizukawa, Y.
Hagino, A. Imamura, M. Saha and H. Takada (2009): Transport and release of chemicals from plastics to theenvironment and to wildlife. Philosophical Transactions of the Royal Society. B364, 2027–2045.
UNEP/IOC (2009): Guidelines on Survey and Monitoring of Marine Litter. Regional Seas Reports and Studies,No. 186, IOC Technical Series, No. 83. 131pp.
UNEP (2014): Valuing Plastics: The Business Case for Measuring, Managing and Disclosing Plastic Use in theConsumer Goods Industry. 116pp.
Woodall, L. C., C. Gwinnett, M. Packer, R. C. Thompson, L. F. Robinson and G. L. J. Paterson (2015): Using aforensic science approach to minimize environmental contamination and to identify microfibres in marine
sediments. Marine Pollution Bulletin, 95, 40-46.

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G1004EN-1

Floating Marine Pollutants (Shipboard Sighting Surveys for
Macro-Debris Items)‫ۑ‬Takashi MIYAO (Japan Meteorological Agency)

1.

Introduction
Floating marine pollutants (debris) are widely distributed in the world's oceans. They can compriseanything from cigarette butts and plastic bags to discarded or lost fishing nets, endangering marine andcoastal wildlife by their ingestion and entanglement; interfere with navigation; cause economic losses;
and threaten human health and safety. Above all, plastics are the most prevalent of marine pollutants,
and remain in the environment for a long time and have a negative impact upon marine ecosystems.
Moreover, with time they break down into small fragments becoming difficult to remove. The sourceof these pollutants source is human activities, especially improper waste disposal and mismanagementof trash and industrial products.
In this chapter, the dedicated shipboard sighting surveys for visible size debris from an elevatedplatform on a moving ship are mainly described. Other possible platforms are airplanes, with thedisadvantage that only large debris items could be determined. In fact, shipboard sighting surveys do
not necessarily need to occur as a stand-alone activity, and are relatively easy method forcrowd-sourcing marine debris sighting (i.e. from ships of opportunity). In spite of their differences inenvironmental factors, they can provide useful information on the spatial and temporal variability offloating debris. Nonetheless, it should be noted that results of sighting survey will be skewed toward
larger debris items.
2.

Objectives and Setting of Surveys

2-1 Objectives

Sighting surveys collect information on the distribution and amounts of visible floating debris
during specific time periods. The most common variables of interest for open-ocean sighting surveys
are density and types of pollutants. Therefore, typical objectives for open-water sighting surveys are,for example, as follows:

to identify types of floating marine pollutants;

to estimate densities of floating marine pollutants;

to detect temporal and spatial variation in the occurrence of floating marine pollutants.

2-2 Site Selection

There have been many studies on macro-debris in beaches and coastal waters, but little
information about abundance and types of floating marine debris in the open-ocean. The survey sites
should be chosen in consideration of the following matters:

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

to deliberate on sources and transportation process affected by the wind system and the major
currents;to focus on areas that are known to accumulate pollutants;



not to impact on marine ecosystems by the navigation of the observation ship.

2-3 Frequency and Timing of Surveys

For long-standing monitoring in fixed region, the minimum sampling frequency should beannually. Ideally quarterly sampling is recommended, allowing an interpretation on seasonal changes.
Bearing in mind that the sighting survey for floating debris is affected by environmental factors, inparticular, sea state and wind speed. Thus the sighting survey should be conducted after a minimum
duration of calm sea, so that there is no bias by floating debris which has been mixed into the watercolumn by recent storms. In addition, it is desirable that the wind speed should be less than 2 in
Beaufort scale (i.e. 3.3 ቂm s-1 ቃ) (DeFishGear, 2013).

3.

Field Measurement

3-1 General Information

Sighting surveys must be conducted in the daytime, from the sunrise to the sunset. Observer(s) ona moving ship stand on the bridge or other elevated section, and continuously focused on the port or
starboard side of the ship. Observer heights above the water line vary according to the type of ship.
The cruising track does not need to be straight, although it is easier to handle the data. Observer(s) willrecord type, size, number and other information on the provided data sheet, as well as ancillary data
(date, time, latitude, longitude etc.), whenever floating pollutant is found (it may be convenient to use
tablet computer instead of the data sheet). If the line transect sampling (see Figure 4-2) is adopted,
perpendicular distance from the cruising track (or sighting distance and angle from the bow) must be
also recorded.
It is desirable that observer(s) use only glare-free side of the ship, especially in dedicated surveys.
Debris object should be detected with the naked eye, and binoculars can be used only for the purpose
to confirm the identity or to estimate sizes of objects. The number of observers on a survey varies, but
it is recommended that a minimum of two observers be employed in any survey (Ribic, 1990).
3-2 Equipment

The observation ship must equip GPS unit for determination of ship position and speed. It is
desirable that some system for visually marking the observation area also can be used.
As mentioned above, debris object should be detected with the naked eye, polarizing glasses may
be useful for protecting eyes from strong sunrays and glare of sea-surface. Binoculars (8 to 10-power
might be adequate) are indispensable to sighting survey. Range finder and/or inclinometer can be used
to measure the distance to detected debris. Digital cameras are also useful to re-confirm the identity of
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debris, to re-estimate sizes of objects, and to record detailed images of floating debris with thecomplicated appearance.
3-3 Variables to Consider(1) Weather Condition
It is desirable to avoid making sighting surveys under poor visibility.

For example, Yoshida andBaba (1985) made no surveys when visibility fell below 200m. Unfavorable sea state, that is highwave and swell, also affect detectability.
(2) Characteristics of Debris
It is well known that color, size, shape, and buoyancy of floating objects affect their detectability.
Large and fine-colored debris are found with ease. Especially, buoyancy has a large effect; lightplastic bottles appeared from the sea surface can be much easily detected than fishing nets floating justbeneath the sea surface. If the line transect approach is taken, the detection function should be
configured for each category of debris.
(3) Vessel Variability
Ship speed and observer heights above the water line affect detectability of floating debris. On
large vessels, observers are typically stand higher above the water line and farther from the bow,which causes objects close to the bow to become undetected. It is considerable fact that ship body
shape might also make undetectable area.
(4) Personnel
Sighting survey of floating marine pollutants should be made by dedicated observer(s) who do nothave other duties at the same time (Ribic et al., 1992; DeFishGear, 2013). Required personnel include
at least two observers experienced or trained in sighting objects floating at sea, who can measure
distances and angle or who can use measuring equipment (range finder, inclinometer, binoculars withreticles etc.). Experienced observers often detect more debris items and estimate distance moreaccurate than inexperienced observers. Novice observers should be trained pairing with skilled
observers.
4.

Data and Metadata

4-1 Pollutant Density

It is strongly recommended that density of debris should be reported in unit of [݅‫ି݉݇ ݏ݉݁ݐ‬ଶ ]; notin [݅‫ି݉݇ ݏ݉݁ݐ‬ଵ ] etc., for quantitative comparisons of different survey. Scanned area can becalculated based on the transect length and width. The transect length will determined from thelatitude and longitude of transect start and end points. Therefore, the ship position should be recorded
whenever a course-change occurred.

Calculating formulas of the pollutant density are given, dividing the number of detected objects by
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scanned area. The method of scanning area estimation should be selected from following two
approaches, depending on the actual situation of the survey.
(1) Strip Transect Approach
When a strip transect approach is adopted, only debris within a specific distance from the side of
the ship are detected (Figure 1). It is assumed that all objects within the strip transect are counted andany objects seen outside the strip transect are not recorded.

Figure 1 Schematic diagram of a strip transect [after Ribic et al., 1992].
W is strip width. Objects labelled "O" are inside of the strip and can be recorded, while object labelled "x"are outside of the strip and not recorded (even if detected).

The practical strip transect width will depend on the debris size and ship speed. In case thatsurveys ensure the detection of debris at 2.5cm size, the preliminary strip transect widths based on
observation height and ship speed are given in Table 4-1. The strip widths most commonly used are
50m and 100m (Ribic et al., 1992), or maximum perpendicular distance from the transect center todetected debris (Thiel et al. 2003; Shiomoto and Kameda, 2005), for larger debris sighting. Generally,
however, these suggested strip widths need to be tested (Lippiatt et al., 2013) and should bedetermined taking into account survey objectives.
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Table 1. Preliminary strip transect widths from different observer height above the water line and the ship
speed (MSFD Technical Subgroup on Marine Litter, 2013).

Observer height above Ship speed
the water line

2 knots

6 knots

10 knots

1m

6m

4m

3m

3m

8m

6m

4m

6m

10 m

8m

6m

10 m

15 m

10 m

5m

Finally, the density of floating debris is given by

where(2) Line Transect Approach

‫=ܦ‬

ܰ
ܰ
=
‫ ܣ‬2ήܹή‫ܮ‬[݅‫ି݉݇ ݏ݉݁ݐ‬ଶ ]ܰ: number of object counted,‫ܣ‬: scanned area [݇݉ଶ ],ܹ: width of strip transect [݇݉],‫ܮ‬: length of transect [݇݉].

When a line transect approach is adopted, all objects are assumed to be counted regardless the
distance from the observer, and perpendicular distance from the ship to the object is measured (Figure2). However, probability of detection equal 1 on the transect center line, and will decreases according
to “detection function” with perpendicular distance. For example, commonly employed detection
functions are:௫మi) The half-normal: g(‫ = )ݔ‬exp ቀെ ଶఙమ ቁ ,௫ఙii) The exponential: g(‫ = )ݔ‬exp ቀെ ቁ ,

௫ ି௕
൨ ,
ఙ

iii) The hazard-rate: g(‫ = )ݔ‬1 െ exp ൤െ ቀ ቁ

where, ‫ ݔ‬is perpendicular distance, ɐ(> 0) and b(> 1) are, respectively, the scale and shapeparameters to be estimated based on survey data.

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Figure 2 Schematic diagram of a line transect [after Ribic et al., 1992].
All objects are assumed to be recorded regardless the distance from the observer. Perpendicular distances tothe object i (Xi) can be estimated directly when they pass just beside observer, or can be calculated from sighting
distance (ri) and angle from the bow (Ti). Using ͆detection function͇, HESW, within which theoretically all
floating debris are detected (meaning in upper part of the figure, s1 = s2), can be estimated.

Using an adequate detection function, “Half the effective strip width: HESW”, within which
theoretically all floating debris are detected, is estimated. Finally, the density of floating debris isgiven by

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D=
where

ܰ
ܰ
=
‫ ܣ‬2 ή ‫ ܹܵܧܪ‬ή ‫ܮ‬[݅‫ି݉݇ ݏ݉݁ݐ‬ଶ ]ܰ: number of object counted,‫ܣ‬: scanned area [݇݉ଶ ],ܹ: Half the effective strip width(‫]݉݇[ )ܹܵܧܪ‬,‫ܮ‬: length of transect [݇݉].

More precisely, detection function should be configured for each category of debris, as mentioned
above.
For further detail of line transect sampling method, see Buckland et al. (2001).
4-2 Classification of Floating Marine Pollutants(1) Size Classes
Floating marine pollutants in the size of a 2.5cm to 1m (in the longest dimension), so-called“macro-debris” (GESAMP, 2015), should be monitored. However, sighting survey will not permit thecorrect measuring of object sizes, the following size classification, introduced by DeFishGear (2013)
and MSFD Technical Subgroup on Marine Litter (2013), are suggested as an example (L denotes thelongest dimension of the pollutants):
i)
ii)
iii)
iv)
v)
vi)

2.5cm ൑ L < 5cm
5cm ൑ L < 10cm

10cm ൑ L < 20cm

20cm ൑ L < 30cm

30cm ൑ L < 50cm
50cm ൑ L

These classes can be merged appropriately at statistical processing. When small debris cannot be
detected owing to observer heights, the lower limit size should be changed.
(2) Identification of Debris
The categories of items for floating debris are desirable to be consistent with the categories
selected for beach litter, seafloor litter and others. For example, UNEP/IOC (2009) introduced sevenlarge classes based on their appearances as follows: i) Containers, ii) Fishing & Boating, iii) Food &Beverage, iv) Packaging, v) Sanitary, vi) Smoking and vii) Other. The Master List of items (MSFD
Technical Subgroup on Marine Litter, 2013) include eight large groups; i) Artificial polymer materials,ii) Rubber, iii) Cloth/textile, iv) Paper/Cardboard, v) Processed/worked wood, vi) Metal, vii)
Glass/ceramics, viii) Others (chemicals, food waste, unidentified).
However, the world common classification does not yet exist. For the practical use during themonitoring, the categories of items can be arranged by object occurrence frequency so that the dataacquisition can be easily done in short time.

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4-3 Metadata

Metadata should include following information:

5.

Survey name, date, time, location



Ship characteristics: Name, type (e.g. research, fishing, regular ferry etc.), tonnage, length,
width etc.

Detail of transect: latitude/longitude of start/end point, ship speed, observer height above thesurface line, total distance covered by transect, scanned areaEnvironmental conditions:(direction/height/period)

wind

speed/direction,

visibility,

wave

and

swell

Concluding Remarks
Shipboard sighting survey for floating marine pollutants can provide valuable information on thedensity and types of marine debris. However, uncertainty in categories of items for floating debris
stays as an unsettled problem yet. Careful consideration to survey design and standardization shouldbe paid in order to develop robust estimates of floating marine pollutants density.
Reference
Buckland, S. T., D. R. Anderson, K. P. Burnham, J. L. Laake, D. L. Borchers, and L. Thomas (2001):
Introduction to distance sampling: estimating abundance of biological population. Oxford University Press,
New York.
DeFishGear (2013): Methodology for Monitoring Marine Litter on the Sea Surface. Visual Observation. Derelict
Fishing Gear management system in the Adriatic Region, 10pp.
Retrieved from [http://issuu.com/defishgear/docs/floating_litter_monitoring_
methodol/10?e=0]
GESAMP (2015): Sources, Fate and Effects of Microplastics in the Marine Environment:

A Global

Assessment (Kershaw, P. J., ed). IMO/FAO/UNESCO-IOC/UNIDO/WMO/IAEA/UN/UNEP/UNDP Joint
Group of Experts on the Scientific Aspects of Marine Environmental Protection. GESAMP Reports &Studies Series, No. 90, 96pp.
Lippiatt, S., S. Opfer and C. Arthur (2013): Marine Debris Monitoring and Assessment. NOAA Technical
Memorandum NOS-OR&R-46.
MSFD Technical Subgroup on Marine Litter (2013): Guidance on Monitoring of Marine Litter in European Seas.
A guidance document within the Common Implementation Strategy for the Marine Strategy Framework
Directive. 128pp.
Ribic, C. A. (Chair) (1990): Report of the working group on methods to assess the amount and types of marine
debris. In Proceedings of the second international conference on marine debris; 2-7 April 1989, Honolulu, HI(R. S. Shomura and M. L. Godfrey, eds.), 1201-1206. NOAA Technical Memorandum. NMFS,NOAA-TM-NMFS-SWFSC-154.
Ribic, C. A., T. R. Dixon and I. Vining (1992): Marine Debris Survey Manual. NOAA Technical Report NMFS
108.

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Siomoto, A. and T. Kameda (2005): Distribution of Manufactured Floating Marine Debris in Near-Shore Areasaround Japan. Marine Pollution Bulletin, 50, 1430-1432.
Thiel, M., I. Hinojosa, N. Vásquez and E. Macaya (2003): Floating marine debris in coastal waters of the SE
Pacific (Chile). Marine Pollution Bulletin, 46, 224–231.
UNEP/IOC (2009): Guidelines on Survey and Monitoring of Marine Litter. Regional Seas Reports and Studies
No. 186, IOC Technical Series No. 83. 131pp.
Yoshida, K. and N. Baba (1985): A survey of drifting stray fishing net fragments in the northern Sea of Japan(Western Pacific Ocean). Document submitted to the 28th Meeting of the Standing Scientific Committee of
the North Pacific Fur Seal Commission, Tokyo, 4-12 April 1985, 13pp.

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List of the editors
Editor in chief, Shigeyoshi OTOSAKA

Vol.1 Editor

Iwao UEKI

Vol.2 Editors

Daisuke SASANO
Yuichiro KUMAMOTO

Vol.3 Editors

Yuichiro KUMAMOTO
Daisuke SASANO
Hajime OBATA

Vol.4 Editors

Hideki FUKUDA
Yuichiro NISHIBE

Vol.5 Editors

Shigeyoshi OTOSAKA
Hideki FUKUDA

Vol.6 Editor

Yuichiro NISHIBE

Vol.7 Editors

Daisuke SASANO
Yuichiro KUMAMOTO

Vol.8 Editors

Iwao UEKI
Daisuke SASANO

Vol.9 Editor

Shigeyoshi OTOSAKA

Vol.10 Editors

Hideaki MAKI
Koichi GOTO

Technical Editors

Michio AOYAMA
Tsuneo ONO

Assistants of the editorial board
Michiyo SUWADA, a current staff of Aoyama Laboratory, Center for Researchin Isotopes and Environmental Dynamics, Univ. of Tsukuba, Japan

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Title: Guideline of Ocean Observations
Volumes 1 - 10
Editor: Committee of Guide of Ocean Observations,
the Oceanographic Society of Japan
Publisher: The Oceanographic Society of Japan
Publication date: December 2016, First Edition
February 2018, Second Edition
April 2018, Third Edition
April 2020, Fourth EditonISBN 978-4-908553-67-7

ISBN 978-4-908553-67-7