ISSN 0386-4049

TECHNICAL REPORTS OF THE METEOROLOGICAL RESEARCH INSTITUTE No.58

2006 Inter-laboratory Comparison Study for Reference
Material for Nutrients in Seawater
気象研究所技術報告第58号
栄養塩測定用海水組成標準の2006年国際共同実験報告
青山道夫、J. Barwell-Clarke、S. Becker、M. Blum、Braga E.S.、S. C. Coverly、
E. Czobik、I. Dahllöf、M. Dai、G. O Donnell、C. Engelke、Gwo-Ching Gong、
Gi-Hoon Hong、D. J. Hydes、Ming-Ming Jin、葛西広海、R. Kerouel、清本容子、
M. Knockaert、N. Kress、K. A. Krogslund、熊谷正光、S. Leterme、Yarong Li、
増田真次、宮尾 孝、T. Moutin、村田昌彦、永井直樹、G. Nausch、A. Nybakk、
M. K. Ngirchechol、小川浩史、J. van Ooijen、太田秀和、J. Pan、C. Payne、
O. Pierre-Duplessix、M. Pujo-Pay、T. Raabe、齊藤一浩、佐藤憲一郎、C. Schmidt、
M. Schuett、T. M. Shammon、J. Sun、T. Tanhua、L. White、E.M.S. Woodward、
P. Worsfold、P. Yeats、芳村 毅、A. Youénou、Jia-Zhong Zhang

気象研究所
METEOROLOGICAL RESEARCH INSTITUTE, JAPAN
December, 2008

2006 Inter-laboratory Comparison Study of a Reference
Material for Nutrients in Seawater
M. Aoyama 1, J. Barwell-Clarke 2, S. Becker 3, M. Blum 4, Braga E. S. 5, S. C. Coverly6,
E. Czobik 7, I. Dahllöf 8, M. H. Dai9, G. O. Donnell10, C. Engelke 11, G. C. Gong 12,
Gi-Hoon Hong 13, D. J. Hydes 14, M. M. Jin 15, H. Kasai 16, R. Kerouel 17, Y. Kiyomono
18, M. Knockaert 19, N. Kress 20, K. A. Krogslund 21, M. Kumagai 22, S. Leterme 23,

Yarong Li 24, S. Masuda 25, T. Miyao 26, T. Moutin 27, A. Murata 28, N. Nagai 29, G.
Nausch 30, M. K. Ngirchechol 31, A. Nybakk 32, H. Ogawa 33, J. van Ooijen34, H. Ota 35,
J. M. Pan 36, C. Payne 37, O. Pierre-Duplessix 38, M. Pujo-Pay 39, T. Raabe 40, K. Saito 41,
K. Sato 42, C. Schmidt 43, M. Schuett 44, T. M. Shammon 45, J. Sun46, T. Tanhua 47, L.
White 48, E.M.S. Woodward 49, P. Worsfold 50, P. Yeats 51, T. Yoshimura52, A.
Youénou53, J. Z. Zhang 54

1)

2)

Coordinator of 2006 inter-laboratory co
Department, Meteorological Rese

Institute of Ocean Sciences Department of Fisheries and Oceans, Sidney, British
Columbia, Canada
3)
Scripps Institution of Oceanography, University of California, San Diego, California,
USA
4)
Monterey Bay Aquarium Research Institute, Moss Landing, California, USA
5)
Instituto Oceanográfico da Universidade de São Paulo, Depto de Oceanografia
Física, Química e Geológica, São Paulo, Brazil
6)
Bran+Luebbe, Norderstedt, Germany*
Present affiliation: SEAL Analytical GmbH, Germany
7)
Water and Catchments Science, New South Wales Department of Environment andConservation, Lidcombe, New South Wales, Australia
8)
Department of Marine Ecology, National Environmental Research Institute-Aarhus
University, Roskilde, Denmark
9)State Key Laboratory of Marine Environmental Science, Xiamen University,
Xiamen, China
10)Marine Environment and Food Safety Services, Marine Institute, County Galway,
Ireland11)
Scottish Environment Protection Agency (SEPA), Marine Chemistry, Scotland,
United Kingdom
12)
Institute of Marine Environmental Chemistry and Ecology, National Taiwan Ocean
University, Keelung, Taiwan
13)
Korea Ocean Research & Development Institute, Kyonggi, South Korea

14)

National Oceanography Centre, Southhampton, United Kingdom
Laboratory for Marine Biogeochemistry and Ecosystem (LAMBS), Second Instituteof Oceanography, Hangzhou, China
16)
Hokkaido National Fisheries Research Institute, Fisheries Research Agency,
Hokkaido, Japan
17)
Institut français de recherche pour l’exploitation de la mer (IFREMER), Center deBrest, Dept. Dyneco/Pelagos, Brest, France
18)
Seikai National Fisheries Research Institute, Fisheries Research Agency, Nagasaki,
Japan
19)
Management Unit of the North Sea Mathematical Models (MUMM), Dept.
MARCHEM, Belgium, Oostende, Belgium
20)
Israel Oceanographic & Limnological Research, Haifa, Israel
21)
School of Oceanography, University of Washington, Seattle, USA
22)
Marine Division, Hakodate Marine Observatory, Hakodate, Japan
23)
School of Biological Sciences, University of Plymouth, Plymouth, United Kingdom
24)
Environmental Forensic and Analytical Science, Department of Environment andConservation (NSW), Lidcombe, NSW, Australia
25)
Marine Division, Nagasaki Marine Observatory, Nagasaki, Japan*
Present affiliation: Marine Division, Global Environment and Marine
Department, Japan Meteorological Agency, Nagasaki, Japan
26)
Marine Division, Global Environment and Marine Department, Japan
Meteorological Agency, Tokyo, Japan*
Present affiliation: Marine Division, Hakodate Marine Observatory, Hakodate,
Japan
27)
Laboratoire d'ocèanographie et de oiogéochimie, UMR6535 CNRS, Centred'ocèanologie de Marseille, Université Aix-Marseille 2, Marseille, France
28)
Institute of Observational Research for Global Change, Japan Agency for
Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
29)
Oceanographical Division, Maizuru Marine Observatory, Maizuru, Japan30)
Department of Marine Chemistry, Leibniz-Institute for Baltic Sea Research,
Rostock-Warnemünde, Germany
31)
University of Guam Marine Lab, Guam, USA*
Present affiliation: Palau Environmental Quality Protection Board, Palau, Palau
32)
Chemical Laboratory, Institute of Marine Research (Norway), Bergen, Norway
33)
Ocean Research Institute, University of Tokyo, Tokyo, Japan
34)
Royal Netherlands Institute for Sea Research (NIOZ), Texel, the Netherlands
35)
Laboratory for Instrumentation and Analysis, General Environmental Technos Co.
(KANSO TECHNOS), Osaka, Japan
36)
The Second Institute of Oceanography, State Oceanic Administration, Hangzhou,
China
37)
Earth and Ocean Sciences Department, University of British Columbia, Vancouver,
British Columbia, Canada
38)
Laboratoire environment resources de Normandie (LERN), Institut français derecherche pour l’exploitation de la mer (IFREMER), Port en Bessin, France
39)
Laboratoire Arago, Centre national de la recherche scientifique, Banyuls sur Mer
cedex, France
40)
AquaEcology, Oldenburg, Germany
15)

41)

Marine Division, Kobe Marine Observatory, Kobe, Japan
Marine Works Japan (MWJ), Yokohama, Japan
43)
Geochemical & Environmental Research Group, Texas A&M University, Texas,
USA
44)
Institute of Biogeochemistry and Marine Chemistry, University of Hamburg,
Hamburg, Germany
45)
Marine Water Monitoring, Government Laboratory, Department of Local
Government and the Environment, Isle of Man Government, Douglas, Isle of Man,
British Isles
46)
Key Laboratory of Marine Ecology & Environmental Sciences, Institute of
Oceanology, Chinese Academy of Sciences, Qingdao, China
47)
Leibenz-Institute of Marine Sciences, University of Kiel, IFM-GEOMAR, Kiel,
Germany
48)
Institute of Ocean Sciences, Department of Fisheries and Oceans, Sidney, British
Columbia, Canada
49)
Plymouth Marine Laboratory, Plymouth, United Kingdom
50)
School of Earth, Ocean & Environmental Sciences, University of Plymouth,
Plymouth, United Kingdom
51)
Ecosystem Research Division, Department of Fisheries and Oceans, Bedford
Institute of Oceanography, Dartmouth, Nova Scotia, Canada
52)
Environmental Science Research Laboratory, Central Research Institute of ElectricPower Industry, Abiko, Japan
53)
Institut français de recherche pour l’exploitation de la mer (IFREMER), Center deBrest, Dept. Dyneco / Pelagos, Plouzane, France54)
Ocean Chemistry Division, Atlantic Oceanographic and Meteorological Laboratory(AOML), National Oceanic and Atmospheric Administration, Miami, USA
42)

Preface
The history of the analysis of nutrients in seawater is long. Nutrients and total
inorganic carbon have been the major observational variables in various international
global ocean observation expeditions, such as the Geochemical Ocean Sections Studyand the World Ocean Circulation Experiment (WOCE). Observation of the naturalvariability of nutrients and inorganic carbon in the world’s oceans, and investigation of
temporal and spatial changes due to the oceans’ response to climate change andincreasing carbon dioxide in the atmosphere, continue to be important topics ofoceanographic research. To address the need for highly accurate and precise data
regarding the effects of climate change on nutrient concentrations, the WOCE
Hydrographic Program office proposed criteria for the precision and accuracy ofnutrient analysis in early 1990. However, attaining these criteria was not possible,
owing to the lack of an accepted standard or reference materials for nutrients inseawater that was applicable to the Pacific Ocean, where the maximum nutrient
concentrations are greater than in the Atlantic and Indian Oceans. Current knowledge
about the variability of nutrient concentrations in seawater is limited because thevariation is very small. Therefore we need traceability and comparability of thenutrients data as well as high accuracy and high precision of them.
The Geochemical Research Department of the Meteorological Research Institute(MRI) of Japan started to develop seawater-based reference materials for nutrient
analysis about ten years ago. This research continues today as part of the “Observational
Study on the Variability of the Carbon Cycle in the Ocean, I (2004–2006) and II(2007–2008)”. A major goal of this research is the development of standard materials
for the analysis of nutrients in seawater that satisfy the requirements for oceanographic
research. The MRI research comprises three parts: the development of seawater-basedreference materials, the conducting of global inter-laboratory comparison study to use
and test the reference materials, and the practical use of the reference materials on board
the R/V Mirai of Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
during a series of research voyages. We are now progressing towards havingseawater-based nutrient reference materials with stability and homogeneity that are
sufficient to satisfy our present requirements. To establish a standard material for
nutrient analysis in seawater, an inter-laboratory comparison study in the world is an
important step.
This technical report summarizes results of the second inter-calibration exercise
conducted by MRI, in which 52 laboratories participated.
Katsumi Hirose
Director of Geochemical Research Department
Meteorological Research Institute序文
海水中の栄養塩の分析は長い歴史がある。海水栄養塩分析の海洋学的目的の一
つは、海水中の栄養塩濃度の自然変動、及びそれに関連して大気中の二酸化炭素の増大やその結果引き起こされる気候変動に応答した海洋の栄養塩の変動を検出することにある。事実、過去にGEOSECSやWOCE等の時代を画するような世界的プロ
ジェクト研究が実施されてきたが、この中で海水中の栄養塩は重要な測定項目として取り上げられてきた。特に、1990年代に実施されたWOCEでは、海洋における栄養塩の変動を検出するため必要とされる分析精度や確度についての目標値が提案された。
しかし、最近まで海水中の栄養塩の分析では、提案された基準（特に、確度）を満足することができていない。その主要な原因は、海水中の栄養塩の分析に関して、基準を満足させるための標準物質ないし参照物質が提供されなかったためである。そのため、現在に至るも海洋における栄養塩の変動に関する知識は限られている。従って、変動を検出するためには、高精度であるばかりでなく追跡可能性（トレーサビリティ）や比較可能性（コンパラビリティ）のある栄養塩データを得るために必要な標準物
質ないし参照物質の確立が求められている。
1990年代の中頃より、気象研究所地球化学研究部（青山）では、海水をベースにした栄養塩の参照物質を作成する研究を始めた。この数年間は、融合型経常研究「海洋における炭素循環の変動に関する観測的研究I（平成16～18年度）及びⅡ（平成19～20年度）」の一部としてこの研究が進められている。主要な目標は、海水中の栄養塩分析に関して海洋学的要求を満たした標準物質システムを構築することである。この研究は、1：海水ベースの栄養塩参照物質の開発、2：参照物質とするための国際比較実験の実施、3：観測船「みらい」の船上での栄養塩分析における参照物質の実用試験からなる。現在、栄養塩参照物質の開発に関して、この条件を満たし安定でしかも均一な海水ベースの参照物質を作成しつつある。この標準物質システム構築の過程で、必要な一歩として、この国際的な相互比較実験がある。
この技術報告では、52機関の参加で得られた第2回国際相互比較実験の結果が取りまとめられている。

地球化学研究部長

廣瀬勝己

Abstract
Autoclaved natural seawater collected in the North Pacific Ocean was used as areference material for analysing nutrient concentrations in seawater during aninter-laboratory comparison study conducted in 2006; this study was a follow-up to asimilar but smaller study conducted in 2003. Homogeneity of sample #2 was confirmedby the repeatability of the nutrient concentration measurements and those interms of one
sigma of standand deviation are: 0.2%, 0.3%, and 0.2% for nitrate, phosphate andsilicate, respectively. Sets of six samples with concentration ranges of 0.1–42.4 μmol
kg-1 for nitrate, 0.0–0.6 μmol kg-1 for nitrite, 0.0–3.0 μmol kg-1 for phosphate, and1.7–156.1 μmol kg-1 for silicate were analysed. A set of samples was distributed to eachof 55 laboratories around the globe (20 countries), and results were returned by 52 of
those laboratories (19 countries).
Analytical precisions reported by the participating laboratories for all deteminands
were generally lower, by at least 50%, than the consensus standard deviations of thereported concentrations. The consensus standard deviations for sample #2 for all
determinands were 5 to 10 times as large as the homogeneities of sample #2 for all
determinands. In some laboratories, the non-linearity of the calibration curve was nottreated effectively.
Our results indicate that variability in the in-house standards of the participating
laboratories and the handling of the non-linearity of the calibration curve of theparticipating laboratories were the primary sources of inter-laboratory discrepancies.
The results confirm that a certified reference material for nutrients in seawater and acommon method for measuring nutrient concentrations are essential for the
improvement of the global comparability of nutrient data in the world’s oceans.

要旨

栄養塩測定用海水組成標準の2006年国際共同実験が行われた、この国際共同実験では、オートクレーブで滅菌処理された天然海水が試料として用いられた。これ
らの試料は、栄養塩測定用海水組成標準の2003年国際共同実験で用いられたものと同様に処理されたものである。試料の均一性は、硝酸塩において0.2％、リン酸塩において0.3％、ケイ酸塩において0.2％であった。六本一組で用いられた試料の濃度範
囲は、硝酸塩が0.1 – 42.4 μmol kg–1 , 亜硝酸塩が0.0 – 0.6 μmol kg–1 , リン酸塩が0.0 – 3.0 μmol kg–1 , ケイ酸塩で1.7 – 156.1 μmol kg–1 である。20カ国55機関に試料が送付され、19カ国52機関から結果が報告された。
各機関から報告された全分析項目の分析繰り返し精度は、報告された値のコンセ
ンサス（合意）濃度の標準偏差（１シグマ）の半分あるいはそれ以下という値であった。
試料番号２について、報告された濃度から導かれたコンセンサス（合意）濃度の標準偏差（１シグマ）は、全分析項目において試料の均一性の5倍から10倍の大きさであった。また、いくつかの機関において分析時に検量線の非直線性を十分に考慮していないことが見出された。
これらの結果は、各機関における栄養塩分析用標準液の違いと分析時における検量線の非直線性の扱い方の違いが、各機関相互の栄養塩濃度の報告値の違いの主たる原因であることを示している。従って、認証標準物質の使用と栄養塩分析における手法の共通化が、全海洋での栄養塩データの追跡可能性（トレーサビリティ）と比較可能性（コンパラビリティ）を確立するために重要である。

Contents
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Introduction ………………………………………….
Samples ……………………………………………..
Participants and response …………………………...
Statistical treatment ………………………………...
Results ……………………………………………...
Conclusions ………………………………………...
Acknowledgments ………………………………...…
References ………………………………...……......

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Appendices
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III
IV
V

List of participating laboratories ……………………...
Results submitted by participating laboratories ………
Scatter plots and histograms of the results
Documents ……………………………………………
History of nutrient inter-laboratory comparison study..

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List of Tables and Figures
TablesTable 1
Table 2
Table 3
Table 4
Table 5
Table 6-1
Table 6-2
Table 6-3
Table 6-4
Table 6-5
Table 6-6
Table 7-1
Table 7-2
Table 7-3
Table 7-4
Table 7-5
Table 7-6
Table 7-7
Table A1
Table A2
Table A3

Homogeneities of sample #2 and analytical precisions for unprocessedseawater
Summary of responses from participants
Statistical data for the six samples
Consensus medians, means, and standard deviations for the six samples
Comparison between consensus standard deviations and homogeneities ofsample #2
Analytical precisions of participating laboratories and consensus standard
deviations for sample # 1
Analytical precisions of participating laboratories and consensus standard
deviations for sample #2
Analytical precisions of participating laboratories and consensus standard
deviations for sample #3
Analytical precisions of participating laboratories and consensus standard
deviations for sample # 4
Analytical precisions of participating laboratories and consensus standard
deviations for sample # 5
Analytical precisions of participating laboratories and consensus standard
deviations for sample # 6
Z-scores for nitrate+nitrite
Z–scores for nitrate
Z–scores for nitrite
Z–scores for phosphate
Z–scores for silicate
Z–scores for phosphate and nitrate+nitrite
Z–scores for phosphate, nitrate+nitrite, and silicate
List of participating laboratories
Laboratory numbers for the 2006 and 2003 inter-laboratory comparison study
Results reported by the participants

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FiguresFigure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure A1-1

Figure A1-2

Ranked nitrate+nitrite concentrations for all samples. The reported
concentrations were ranked using the concentrations for sample #3.
Ranked nitrate concentrations for all samples. The reported concentrations
were ranked the using the concentrations for sample #3.
Ranked nitrite concentrations for all samples. The reported concentrations
were ranked using the concentrations for sample # 1.
Ranked phosphate concentrations for all samples. The reported concentrations
were ranked using the concentrations for sample #3.
Ranked silicate concentrations for all samples. The reported concentrations
were ranked using the concentrations for sample #2.
Nitrate+nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrate+nitrite concentrations of sample # 1 (lower
panel)
Nitrate+nitrite concentration versus laboratory number (upper panel)

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Figure A1-3

Figure A1-4

Figure A1-5

Figure A1-6

Figure A2-1
Figure A2-2
Figure A2-3
Figure A2-4
Figure A2-5
Figure A2-6
Figure A3-1
Figure A3-2
Figure A3-3
Figure A3-4
Figure A3-5
Figure A3-6
Figure A4-1

Figure A4-2
Figure A4-3
Figure A4-4

Figure A4-5

Figure A4-6

Frequency distribution of nitrate+nitrite concentrations of sample #2 (lower
panel)
Nitrate+nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrate+nitrite concentrations of sample #3 (lower
panel)
Nitrate+nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrate+nitrite concentrations of sample # 4 (lower
panel)
Nitrate+nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrate+nitrite concentrations of sample # 5 (lower
panel)
Nitrate+nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrate+nitrite concentrations of sample # 6 (lower
panel)
Nitrate concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample # 1 (lower panel)
Nitrate concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample #2 (lower panel)
Nitrate concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample #3 (lower panel)
Nitrate concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample # 4 (lower panel)
Nitrate concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample # 5 (lower panel)
Nitrate concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample # 6 (lower panel)
Nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrite concentrations of sample # 1 (lower panel)
Nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrite concentrations of sample #2 (lower panel)
Nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample #3 (lower panel)
Nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample # 4 (lower panel)
Nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrate concentrations of sample # 5 (lower panel)
Nitrite concentration versus laboratory number (upper panel)Frequency distribution of nitrite concentrations of sample # 6 (lower panel)
Phosphate concentration versus laboratory number (upper panel)Frequency distribution of phosphate concentrations of sample # 1 (lower
panel)
Phosphate concentration versus laboratory number (upper panel)Frequency distribution of phosphate concentrations of sample #2 (lower panel)
Phosphate concentration versus laboratory number (upper panel)Frequency distribution of phosphate concentrations of sample #3 (lower panel)
Phosphate concentration versus laboratory number (upper panel)Frequency distribution of phosphate concentrations of sample # 4 (lower
panel)
Phosphate concentration versus laboratory number (upper panel)Frequency distribution of phosphate concentrations of sample # 5 (lower
panel)
Phosphate concentration versus laboratory number (upper panel)Frequency distribution of phosphate concentrations of sample # 6 (lower
panel)

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Figure A5-1
Figure A5-2
Figure A5-3
Figure A5-4
Figure A5-5
Figure A5-6

Silicate concentration versus laboratory number (upper panel)Frequency distribution of silicate concentrations of sample # 1 (lower panel)
Silicate concentration versus laboratory number (upper panel)Frequency distribution of silicate concentrations of sample #2 (lower panel)
Silicate concentration versus laboratory number (upper panel)Frequency distribution of silicate concentrations of sample #3 (lower panel)
Silicate concentration versus laboratory number (upper panel)Frequency distribution of silicate concentrations of sample # 4 (lower panel)
Silicate concentration versus laboratory number (upper panel)Frequency distribution of silicate concentrations of sample # 5 (lower panel)
Silicate concentration versus laboratory number (upper panel)Frequency distribution of silicate concentrations of sample # 6 (lower panel)

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