Off-site decontamination andremediation following the Fukushima
Daiichi NPP accident
Results elaborated in the Fukushima
Prefecture and comparison with global
experience
Cooperation between theInternational Atomic Energy Agency
and Fukushima Prefecture

Final version: September 2023

FOREWORD
The 11 March 2011 earthquake off the Pacific coast of Tohoku and the subsequent tsunami andaccident at Tokyo Electric Power Company’s Fukushima Daiichi Nuclear Power Plant(hereinafter referred to as ‘Fukushima Daiichi accident’) resulted in radioactive contamination
deposited in various areas of Japan, including Fukushima Prefecture.
In December 2012 the International Atomic Energy Agency and the Fukushima Prefecture
signed a Practical Arrangement with the objective to define the framework for cooperation
between the Prefecture and the Agency to provide broad and extensive assistance to thePrefecture in areas related to radiation monitoring and remediation in order to ensure ongoingprotection of people and the environment from ionizing radiation resulting from the 2011
Fukushima Daiichi accident. The cooperation was designed to complement existing Japaneseactivities and to provide immediate assistance and support which will be of direct benefit toresidents of the Prefecture as well as visitors to the Prefecture.
This publication summarises the studies discussed as part of the cooperation project between
the Fukushima Prefecture and the International Atomic Energy Agency on decontamination
and remediation in the Fukushima Prefecture; this cooperation project ran from 2012–2022.
The report covers the experience gained in Fukushima Prefecture in environmental monitoringof radionuclides and specific studies of the behaviour of radiocaesium in the environment. The
focus is on comparing observations made in Fukushima Prefecture after the accident with dataobtained in studies conducted in other parts of the world. Similarities and differences inobservations following the Chernobyl and Fukushima Daiichi nuclear power plant accidents
are highlighted. This publication is intended to share this work with all IAEA Member States.
The IAEA is grateful to all participants of the Cooperation Project from the Fukushima
Prefecture and the International Atomic Energy Agency. The contributions of the Fukushima
Prefecture and the international experts in drafting and review of this publications are
acknowledged. The IAEA officers responsible for this publication are T. Yankovich and
J. Brown of the IAEA Division of Radiation, Transport and Waste Safety.

CONTENTS
SUMMARY ...................................................................................................................... 1
1.

INTRODUCTION ................................................................................................... 3
1.1.
1.2.
1.3.
1.4.

BACKROUND .......................................................................................... 3
OBJECTIVES ............................................................................................ 4
SCOPE ....................................................................................................... 5
STRUCTURE OF THE REPORT ............................................................. 52.

BEHAVIOUR OF RADIOCAESIUM IN THE ENVIRONMENT ........................ 6

3.

STRUCTURE FOR A COMPREHENSIVE COMPILATION OF
RESULTS IN A MATRIX ...................................................................................... 7

4.

RADIOCAESIUM IN FRESHWATER SYSTEMS ............................................. 10
4.1.
4.2.

4.3.

4.4.
4.5.

5.

TRANSFER PROCESSES ...................................................................... 10
RADIOCAESIUM IN RIVER WATER ................................................. 10
4.2.1. Particulate and dissolved radiocaesium ....................................... 10
4.2.2. Leaching of 137Cs from litter and concentrations of dissolved
137
Cs in run-off water ................................................................... 15
4.2.3. Dynamic of 137Cs in four headwater catchments ......................... 16
RADIOCAESIUM OF CAESIUM-137 IN SUSPENDED
SEDIMENTS ........................................................................................... 17
4.3.1. Interaction of flow rate, concentration of suspended sedimentand Cs-levels of suspended sediments ......................................... 17
4.3.2. Origin of suspended sediments in rivers during high water
periods .......................................................................................... 18
4.3.3. Normalized 137Cs activity concentration in suspended
sediments ..................................................................................... 20
4.3.4. Land-use and 137Cs-loss with surface run-off .............................. 20
4.3.5. Flux of 137Cs with suspended sediments ...................................... 24
MODELLING THE CONCENTRATIONS OF DISSOLVED AND
PARTICULATE CAESIUM-137 IN RIVER WATER .......................... 26
COMPARISON OF JAPANESE AND INTERNATIONAL
EXPERIENCE ON THE DYNAMIC OF CAESIUM-137 IN
RIVERS ................................................................................................... 27
4.5.1. Effective half-lives of 137Cs in river water................................... 27
4.5.2. Loss of 137Cs from catchments..................................................... 28

EXPERIENCE MADE DURING DECONTAMINATION WORK .................... 30
5.1.
5.2.

5.3.

EFFECT OF DECONTAMINATION ACTIVITIES ON RIVERS
AND CATCHMENTS ............................................................................ 30
DECONTAMINATION OF RIVERBEDS AND RIVERBANKS ........ 30
5.2.1. Impact of typhoons and flood events on the persistence of
decontamination ........................................................................... 32
INTERNATIONAL EXPERIENCE ON REMEDIATION OF
RIVERS ................................................................................................... 32
5.3.1. Administrative measures.............................................................. 34
5.3.2. Technical measures ...................................................................... 34

6.

MICRO PARTICLES CONTAINING CAESIUM-137........................................ 37
6.1.
6.2.
6.3.

7.

SUCCESS OF DECONTAMINATION WORK .................................................. 41
7.1.
7.2.

8.

DECONTAMINATION ACTIVITIES IN THE FUKUSHIMAPREFECTURE ........................................................................................ 41
INTERNATIONAL EXPERIENCE IN DECONTAMINATION
AND REMEDIATION IN TERRESTRIAL ENVIRONMENTS .......... 43

INTERACTION WITH THE PUBLIC ................................................................. 45
8.1.
8.2.

9.

GENERAL INFORMATION ON MICROPARTICLES ....................... 37
CSMPS FOUND IN SUSPENDED SEDIMENTS OF THE
HAMADORI RIVER .............................................................................. 37
INTERNATIONAL EXPERIENCE ON PARTICLES WITH
ENHANCED RADIONUCLIDE CONCENTRATIONS ....................... 39
6.3.1. Condensation particles ................................................................. 39
6.3.2. Fuel particles ................................................................................ 39
6.3.3. Environmental behaviour ............................................................. 39
6.3.4. Fukushima CsMPs and Chernobyl hot particles .......................... 40

ACTIVITIES IMPLEMENTED AFTER FUKUSHIMAACCIDENT ............................................................................................. 45
INTERNATIONAL EXPERIENCE ....................................................... 46

SUMMARY ........................................................................................................... 48

APPENDIX I. DYNAMICS OF CAESIUM-137 IN JAPANESE AND
EUROPEAN RIVERS ........................................................................................... 51
APPENDIX II. TIME-DEPENDENCE OF CAESIUM-137 IN SUSPENDED
SEDIMENTS OF RIVERS OF THE FUKUSHIMA PREFECTURE .................. 55
APPENDIX III. FLUX OF CAESIUM-137 IN RIVERS OF THE FUKUSHIMAPREFECTURE ...................................................................................................... 85
REFERENCES ................................................................................................................ 89

SUMMARY
The accident at the Fukushima Daiichi nuclear power plant, caused by an earthquake andtsunami on 11 March 2011, resulted in the release of radionuclides into the environment. The
deposition of radiocaesium in Fukushima Prefecture was very heterogeneous; the most affectedareas are located in the northwest of the power plant in a mountainous area that is predominantly
covered by forests and is home to many freshwater bodies such as rivers, lakes and reservoirs.
In response to the accident, restrictions on the consumption of foodstuffs were imposed by theJapanese authorities. Immediately after the accident, monitoring programmes started to checkcompliance with the limits for activity concentrations in food and to assess gamma dose rates
in air against the reference level for members of the public set by the Government of Japan. In
addition, research programmes were initiated to analyse in detail the behaviour of radiocaesiumin the terrestrial and aquatic environment. The Fukushima Prefecture played a key role inplanning and implementation of countermeasures as well as in providing technical advice to themunicipalities.
In December 2012, a cooperation between the Fukushima Prefecture and the International
Atomic Energy was initiated in the fields of management of remediation waste, radiation
monitoring and of decontamination and remediation of areas and water bodies affected bydeposition of radionuclides. The focus of the cooperation was on analyzing and discussing theradiological situation in the Prefecture and providing technical advice to the Prefecture basedon international best practices developed in these fields since the 1950s.
This report summarizes the results of this cooperation in the field of decontamination andremediation of areas affected by the deposition of radionuclides due to the accident in the
Fukushima Daiichi Nuclear Power Station. The main topics covered in the report are: (i) the
behaviour of radiocaesium in freshwater bodies; (ii) the dislocation of 137Cs in watersheds ofrivers in the Fukushima Prefecture; (iii) remediation work in the Fukushima Prefecture;(iv) aspects of the characteristics of microparticles containing 137Cs (CsMPs); (v) anddissemination of information to the public on the radiological status in the Fukushima
Prefecture, on the planning and on the progress of decontamination activities.
This report provides a compilation and analyses the radioecological information obtained
during Fukushima Prefecture’s cooperative project with the IAEA between 2012 and 2022 withthe objective of contributing to the global dissemination of the experience gained by Fukushima
Prefecture in the field of the behaviour of radiocaesium in the environment and the effectivenessof decontamination and remediation after the accident.

1

1.

INTRODUCTION

1.1. BACKROUND
As a result of the earthquake off the Tohoku Pacific coast on11 March 2011, and the resulting
tsunami, an accident occurred at the Fukushima Daiichi nuclear power plant in Japan.
Radionuclides were released into the environment and deposited particularly in Fukushima andthe neighbouring Prefectures. Immediately after the accident, monitoring programmes were
initiated to determine gamma-dose rates and their time-dependence, radionuclide levels infoodstuffs and in environmental media to study the behaviour of radionuclides in theenvironment.
Requirements for the protection of people and the environment in existing exposure situations
in areas affected by enhanced levels of radionuclides are established in IAEA Safety Standards
Series No. GSR Part 3, Radiation Protection and Safety of Radiation Sources: International
Basic Safety Standards [1]. Recommendations on planning and implementing the remediationof sites and areas affected by such past activities and events to meet the requirements
established in the Basic Safety Standards are given in IAEA-GSG-15 [2].
To support Member States in the practical management of areas affected by past activities,
IAEA has published technical reports describing decontamination and remediation techniques
and their effectiveness in reducing activity and radiation levels in the environment. Important
publications are e.g.: (i) Guidelines for Agricultural Countermeasures Following an Accidental
Release of Radionuclides [3]; (ii) Guidelines for Remediation Strategies to Reduce theRadiological Consequences of Environmental Contamination [4]; (iii) Assessment ofRadioactive Contamination and Effectiveness of Remedial Measures in Urban Environments[5]; and (iv) Ten Years of Remediation Efforts in Japan [6]. Technical Volume 5 the IAEA
report on The Fukushima Daiichi accident [7] provides a comprehensive description of on-siteand off-site recovery efforts implemented after the accident. The IAEA report on an
International Expert Meeting on Decommissioning and Remediation after a Nuclear Accident[8] summarizes the experience gained and the lessons learned from decommissioning andremediation projects implemented in various Member States.
In December 2012 the IAEA and the Prefecture signed an agreement titled Practical
Arrangements between Fukushima Prefecture and the International Atomic Energy Agency on
Cooperation in the Area of Radiation Monitoring and Remediation (hereinafter referred to as‘Practical Arrangements’).
The Practical Arrangements were modified and extended in April/May 2016 and again in
December 2017 to consider other areas of work and activities in which cooperation may be
pursued.
The activities that were part of the Practical Arrangements under which IAEA has provided
assistance to the Prefecture can be summarized as:⎯⎯⎯

Research and studies on radiation monitoring in terrestrial and aquatic environments,
including application of environmental mapping technology by using unmanned aerial
vehicles and long term monitoring of radioactive materials;
Research and studies on remediation of terrestrial and aquatic environments in the
Prefecture;
Research and studies on the management of radioactive waste from remediation.

3

The objective of the cooperation was to provide comprehensive support to the prefecture inthese areas to ensure the protection of people and the environment from ionizing radiation
resulting from the 2011 Fukushima Daiichi accident. The cooperation was designed tocomplement ongoing Japanese activities and to provide immediate assistance and support forthe direct benefit to residents of the Prefecture as well as visitors to the Prefecture. IAEA’s
activities in implementing these projects focused on providing effective technical assistanceand support to the prefecture based on international experience and best practices.
Some of the data summarised in this publication have been analysed within the IAEA Models
and Data for Radiological Impact assessment programme (MODARIA) [9]. Results ofradioecological studies carried out in Japan after the accident have also been summarized andcompared with pre-accident data collected in Japan and with existing data from other parts of
the world covering a wider range of topics and environments [10, 11].
1.2. OBJECTIVES
The objective of this publication is to provide a compilation and analyses of the radioecologicalinformation obtained during Fukushima Prefecture's cooperative project with the IAEA
between 2012 and 2022 which can contribute to the global dissemination of the experience
gained after the FDNPP accident in 2011. The focus of the report is on the behaviour ofradiocaesium in the environment and the effectiveness of decontamination and remediation
after the accident.
As part of the IAEA’s cooperation with Fukushima Prefecture, international experts and IAEA
staff provided technical advice based on IAEA safety standards and international best practices
for evaluating measurements results as well as on planning and implementing the measurescarried out by the Prefecture. Additionally, results of studies on the fate of radiocaesium in theenvironment conducted by other research institutes were also included in the discussion. The
topics covered in the report are:

⎯
⎯
⎯
⎯
⎯
⎯

The behaviour of 137Cs in freshwater bodies including time-trends of radiocaesium inwater, and suspended and bottom sediments;
Loss of 137Cs from catchments with surface run-off;Remediation activities and their effectiveness in freshwater bodies of the Fukushima
Prefecture;
Characteristics of Micro-Particles containing radiocaesium (CsMPs);
Interaction with the public and experience with dissemination of results;
Review of global experience in these areas gained during remediation activities following
enhanced releases of radionuclides to the terrestrial and aquatic environment in other partsof the world.

The publication summarizes the information acquired during the cooperation project; it includes
data obtained during the related programs on monitoring radiocaesium activities in theenvironment as well as research projects set up to investigate specific topics on theenvironmental transport of radiocaesium.
This publication is primarily intended to share this experience gained in the Prefecture on
environmental transfer data from Japan after the release of radionuclides to the environment
from the FDNPP with the IAEA Member States. The information compiled and summarized inthis report compliments other reports that have aimed to summarize radioecological studies

4

carried out in Japan after the accident and compare with pre-accident data collected in Japanand with existing data, for example see Refs [10, 11].
1.3. SCOPE
This publication provides information which is useful for informing the management of areas
affected by enhanced levels of radiocaesium after an accident. The measurements and resultsof the research projects undertaken in the Prefecture can assist in the following ways:

⎯
⎯
⎯
⎯
⎯

Estimation of the time-dependence of radiocaesium in water and sediments of freshwater
bodies following short-term deposition on catchment areas;
Estimation of the importance of surface run-off for the movement of radiocaesium incatchment areas;
Evaluation of the effectiveness and persistence of remediation measures in freshwater
bodies;
The selection of decontamination measures using the information on the effectiveness ofremedial actions in residential areas;
The activities on the interaction with the public may also help to set up remediation
strategies that are acceptable to stakeholders.

1.4. STRUCTURE OF THE REPORTThe report consists of nine sections and three appendices. A brief overview of the behaviour ofradiocaesium in the environment is given in Section 2. Section 3 describes the possible structure
for compiling the results into a matrix. Section 4 describes the behaviour of radiocaesium in theaquatic environment in Fukushima Prefecture and compares the results with the worldwide
experience in this field. Section 5 summarizes Japanese and worldwide experience made during
in decontamination work in freshwater systems. Section 6 focuses on the abundance andcharacteristics of radiocaesium-containing microparticles (CsMPs) released from the FDNPP
during the accident. Section 7 compares the success of decontamination work in residential
areas of Fukushima Prefecture with worldwide experience. Section 8 highlights some aspects
of interaction with the public after the accident, and Section 9 summarizes the main findings ofthe report.
The report has three Appendices. Appendix I summarizes data on the dynamics of 137Cs in
Japanese and European rivers; Appendix II lists the 137Cs activity concentrations in suspended
sediments of rivers of the Fukushima Prefecture from 2011–2021; and Appendix III presents
the flux of 137Cs in rivers of the Fukushima Prefecture.

5

2.

BEHAVIOUR OF RADIOCAESIUM IN THE ENVIRONMENT

During the accident, a wide spectrum of radionuclides was released. Most of them were short
lived, so they decayed away within weeks or months. In the long term, the most importantradionuclides are 134Cs and 137Cs. In 2011, the ratio of 134Cs and 137Cs was approximately 1.
Due to the different half-lives of 134Cs (2.06 years) and 137Cs (30.1 years), the 134Cs/137Cs-ratio
will drop to about 0.017 by March 2024.
The deposition of radiocaesium in the Fukushima Prefecture was very heterogeneous; the mostaffected areas are in the north-west of FDNPS (Figure 1). This is mountainous area, it is covered
mainly by forests, and it houses many freshwater water bodies, such as rivers, lakes, andreservoirs.
Much of the knowledge on the behaviour of caesium in the environment has been gained during
the last 70 years. Radiocaesium has been released to the environment during nuclear weapons
testing, during operation of nuclear facilities, and during nuclear accidents. The key
characteristic controlling the behaviour of caesium in the environment is its strong sorption tomineral components both in soils and in suspended and bottom sediments of water bodies. In
general, this causes a slow migration in soil, a considerable accumulation in sediments and a
low uptake of caesium by plants. However, uptake of caesium from soil may be higher by ordersof magnitude on acid, organic soils with insufficient potassium supply [12], as well as on
tropical soils with advanced degradation of clay minerals [13].
Due to the strong sorption to suspended matter in freshwater environments, caesium deposits
effectively to bottom sediments, and caesium levels in the water column decline quickly.
Therefore, the transport of caesium in rivers and lakes with moving sediments is an important
process. The uptake of caesium by fish and other biota is effective, in particular in waters withlow potassium concentrations.

FIG. 1: Deposition of 137Cs in the Fukushima Prefecture as of 14 June 2011 [14].
6

3.

STRUCTURE FOR A COMPREHENSIVE COMPILATION OF
RESULTS IN A MATRIXMuch work has been carried out in the Fukushima Prefecture to study the behaviour ofradionuclides in the environment and various aspects related to decontamination of affectedareas. For facilitating the access to the knowledge, the set-up of a matrix has been suggested to
document the data in a structured manner. The comprehensive and concise compilation of thedata in this way can facilitate the comparison of results achieved in the Fukushima Prefecturewith global experience in these fields.
The proposed structure of the matrix is shown in Table 1. However, rather than a table, thematrix defines a structure for reporting the data and supporting information. In most cases it notpossible to include the results of investigations as simple datapoints in a table. Many data setsconsist of many individual data collected at different places over many years which require aparameter- and process-specific presentation.
For compiling results of studies on the behaviour of radionuclides and on decontamination work
carried out in the Fukushima Prefecture and elsewhere, the following processes are included;
more processes can be considered, as necessary and appropriate:

⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯

Time dependence of 137Cs in river water;
Time dependence of 137Cs in water of dams lakes and reservoirs;
Time dependence of 137Cs in bottom sediments of freshwater bodies;
Loss of 137Cs from catchments/catchment areas;
Effective half-lives of 137Cs in river water and suspended sediments;
Micro-particles with enhanced levels of radiocaesium in the environment;
Decontamination (rivers);
Decontamination (residential area).

For each process, several descriptors are needed to allow a quick overview and a simple(preliminary) evaluation of the results. These descriptors are:

⎯
⎯
⎯
⎯
⎯

⎯
⎯

Definition of the parameter/quantity;
Sampling location;
Observation period;
Unit of the parameter/quantity reported;
Results to be presented ⎯ as appropriate⎯ as:• Single values, individual data points,• Time series of values (figures and/or tables),• Spatial distribution of quantities or parameter values,• Functions describing the results in dependence of one or more variables;
Key influencing factor(s);Dependence of the process on the influencing factor(s), any other remarkable point tocharacterise the process considered.

7

Table 1. Proposed matrix to define a structure for comprehensive and concise compilation of data elaborated in the Fukushima Prefecture and elsewhere
Process

Parameter/quantity

1

Time dependenceof Cs-137 in river
water

2

Time dependenceof Cs-137 in dam
lake / water
reservoir

3

Time dependenceof Cs-137 in bottom
sediments offreshwater bodies

4

5

6

Unit

ValuesInfluencing factor(s)Measured levels of dissolved Cs-137
Measured levels of particulate Cs-137
Simulated levels of dissolved Cs-137
Simulated levels of particulate Cs-137
Measured levels of dissolved Cs-137
Measured levels of particulate Cs-137
Simulated levels of dissolved Cs-137
Simulated levels of particulate Cs-137
Measured levels of particulate Cs-137

Bq/m³
Bq/kg
Bq/m³
Bq/kg
Bq/m³
Bq/kg
Bq/m³
Bq/kg
Bq/m³

Time series formonitoring points
in a river

Flow rate
Turbidity
Conc. of suspended sediments

Simulated levels of particulate Cs-137

Bq/kg

Loss of Cs-137
from catchment
areas
Ecological half-lives

Loss of Cs-137 from catchments/
catchment areas

Micro-particles inthe environment

Cs-MPs found

Bq/ m² a,(lost activity per unit area
per time)days or year
Number of components
identified
Number of particles
foundParticles per unit area
Main elements in theparticles (mg/kg)
Bq per particles
Bq/kg
As applicable:
Activity (Bq/kg) in
before and after
decontamination
Activity (Bq/m²) before
and after
decontamination
Dose rate before and after
decontamination

Reduction of Cs-137 in environmental
media with time

Composition
Activity

8

7

Decontamination(river)Decontamination measure (e.g.
removal of shore sediments, removal ofbottom sediments, removal of weed)

8Decontamination(residential area)

Decontamination measure (e.g.
removal of ……)

Sampling
location

Observation
periodTime series formonitoring points
in dam lake / water
reservoir
Time series formonitoring points
in a river / dam lake/water reservoir
Land use, slope of the terrain, precipitation,
number of events with high precipitation,
catchment area
Time after the accident, media considered,environmental conditions
Particle type

Rainfall after decontamination,
High rainfall events after precipitation,
Slope of the terrain
Intensity of decontamination, area
decontaminated, amount of material (soil,
sediments, litter, etc.) removed, decontamination
measures applied,

The format of the results to be reported depends on the nature of the process. The results ofstudies may be reported as e.g. single values, time series of values, or functions describing thedependency of the results on one or more variables, as appropriate. Maps can be used to show
spatial distributions of parameters or activity levels in environmental media. Since any process
requires an individual format for presenting results, a more specific definition of the format is
not possible.
Data available from other countries can be reported as well in the same structure. This will
facilitate the comparison with the studies carried out in the Fukushima Prefecture.
The matrix should not be considered as a ‘big table’ to include data in formalized way. Veryoften, this is not possible, since the results are available as time series over many years with alarge number of individual points.
The matrix provides a general structure for the reporting of data on the work done in the
Fukushima Prefecture and in other parts of the world.
Results available from the Fukushima Prefecture are summarized in the following sections andcompared with studies carried out in other countries, for different aspects of radioactive
contamination of the environment. The results presented could provide the basis for integrationin the data structure presented above.

9

4.
4.1.

RADIOCAESIUM IN FRESHWATER SYSTEMS

TRANSFER PROCESSES

Water from rivers, lakes, and reservoirs is widely used as drinking and irrigation water as well
as for industrial purposes. The accident in 2011 led to catchment areas being contaminated thatare essential for the water supply of the Fukushima Prefecture.
A scheme of the transport of caesium in a freshwater system is shown in Figure 2. The driving
force for the transport of radiocaesium from the catchment area to freshwater bodies is the flowof water. Since radiocaesium is strongly absorbed by mineral components of the soil, it ismainly transported attached to sediments. The amount of radiocaesium in run-off water is theresult of a complex interaction of land-use (vegetated, paved, bare soil), amount and intensityof precipitation, and the slope of the surface.
Freshwater systems include rivers, lakes, and reservoirs. The use of water for irrigation or as
drinking water for humans represents a link to the human environment. The radiocaesiumtransport in a catchment is not continuous but varies depending on precipitation and surface
water runoff. During dry periods, it may be very low, whereas it may increase by orders ofmagnitudes during high rainfall events. Then, rivers may overflow and areas within thecatchment may become flooded and contaminated suspended matter carried with the water may
deposit on flood plains.
With regard to the great importance of the freshwater bodies for the water supply of the
Fukushima Prefecture, monitoring activities were initiated for caesium in freshwater bodies
immediately after the accident in 2011. The monitoring programs included the following
activities:

⎯
⎯
⎯
⎯
⎯

⎯

Measurement of radiocaesium in water in dissolved and particulate form;
Measurement of radiocaesium in bottom sediments;
Loss of radiocaesium from catchments;
Transport of radiocaesium with river water;
Hydrological characteristics:• Measurement of water levels and flow rates,• Precipitation,• Turbidity;
Water composition:• Concentrations of major ions (potassium, calcium, magnesium, and ammonium),• Concentration of suspended sediments.

For this purpose, along the Abukuma River and on rivers draining coastal catchments,
30 monitoring stations were installed (Figure 3).
4.2. RADIOCAESIUM IN RIVER WATER
4.2.1.

Particulate and dissolved radiocaesiumRadiocaesium in freshwaters is present in dissolved and particulate form. Because of the strong
sorption of caesium to clay particles, the greatest fraction of radiocaesium is attached tosuspended sediments. In calm waters as lakes and reservoirs and in rivers with low flow rates,
suspended sediments quickly deposit to the bottom sediments.
10FIG. 2: Scheme of the transport of radiocaesium from the catchment to the ocean (red arrows indicate
the transport between compartments).

FIG. 3: Map of 137Cs-deposition calculated for 2 July 2011. Red shaded areas indicate theoriginal evacuation zone. The numbers in the map correspond to the sites listed in Table 6. (Figure from
Ref. [15]).

11

Figure 4a shows the absolute and normalized 137Cs-activity concentration in suspended
sediments, and Figure 4b shows the absolute and normalized activity concentration of dissolved
137
Cs in water of rivers of the Fukushima Prefecture covering the period from 2011 to 2021
[15–17]. The normalized activity concentrations of particulate and dissolved 137Cs represent thequotient of the activity concentrations of 137Cs and the mean 137Cs deposition per unit area inthe catchment. Normalization allows for better comparability between watersheds byeliminating the influence of varying deposition densities. The data include the main channel ofthe Abukuma River system, and nine smaller river systems in the Hamadori area.
Immediately after the deposition, the values of 137Cs-concentrations in suspended sediments
exceeded 10 000 Bq/kg; since then, levels have steadily declined. The variations of the 137Cs
activity concentrations in suspended sediment are pronounced and cover 1–2 orders ofmagnitudes; in the rivers of the Hamadori area, the variations cover even up to three orders ofmagnitude. However, this variation is not surprising as the catchments related to the rivers varyin 137Cs -deposition, size, slope, and land-use. The variation of the normalized concentration ofsuspended sediments is lower. The underlying data for Figure 4 for the activity concentrationof 137Cs in suspended sediments from 2011–2021 [16] are summarized in Appendix II below.
There are fewer measurements for dissolved 137Cs in river water. Caesium is strongly sorbed
by suspended sediments, therefore the concentrations of dissolved 137Cs in river water isrelatively low. In the Abukuma River and its tributaries, the values drop from some hundred
mBq/L to some mBq/L at the end of the observation period. In the rivers of the Hamadori area,
the decline is less pronounced. The levels of dissolved radiocaesium in water are far below theWorld Health Organization [18] recommended quality criterion for 137Cs in drinking water of
10 Bq/L, this level is marked in Figure 4b (top). The underlying data for Figure 4 for the activity
concentration of dissolved 137Cs in river water from 2017–2021 [17] are also summarized inAppendix II.
The time-dependence of 137Cs in freshwaters is quantified by the effective half-life1, which
integrates all processes that cause a decline of 137Cs concentrations in environmental media [12]as e.g. radioactive decay, migration, and movement of sediments.
The effective half-lives determined for particulate and dissolved 137Cs in the rivers monitored
in the period of 2012–2021 are summarized in Table 2. The concentrations of particulate 137Cs
decline slightly slower, and the variation of half-lives is less than for dissolved 137Cs. In general,the differences to dissolved 137Cs are not considerable.
The time dependence of the concentration of particulate and dissolved 137Cs in the Hiso andWariki River from 2011–2021 is presented in Figure 5. In both rivers, there is a continuous,
relatively smooth decline during the whole observation period. A fast component immediately
after the deposition is followed by a slower component starting a few months after deposition.
Nakanishi and Sakuma [19] studied the decline of particulate and dissolved 137Cs in water of
the Ukedo and Ota Rivers during 2015 and 2018. In this period, effective half-lives forparticulate 137Cs were observed of 2.1 and 1.5 years for Ukedo and Ota River, respectively. The
decline of dissolved 137Cs was slower with effective half-lives of 3.3 for the Ukedo River and2.2 years for the Ota River. The values are in the same range as given in Table 2.
The values in Table 2 for the effective half-lives for 137Cs in river water are somewhat
shorter; however, it should be noted that the observation period in Table 2 is from 2012 to 2021
[15–17, 20], whereas it is 2015–2018 in Ref. [19]. Therefore, it is important not tooveremphasize the differences.

1

Decline of 137Cs activity concentrations in river water due to ecological processes and physical decay.

12FIG. 4a: Absolute (top) and normalized (bottom) activity concentration in of 137Cs in suspended
sediments in water of rivers of the Fukushima Prefecture from 2011–2021 [16]. (The bottom of the
figure on normalized 137Cs activity concentration of 137Cs in suspended sediments was kindly provided
by the Fukushima Prefecture). Image credit: Fukushima Prefecture2.
(The numbers represent the following rivers: 1 Mizusakai River, 2 Kuchibuto River, Upstream,
3 Kuchibuto River Midstream, 4 Kuchibuto River Downstream, 5 Fushiguro, 6 Iwanuma, 7 Mano,
8 Ojimadazeki, 9 Matsubara, 10 Onahama, 11 Tsukidate, 12 Nihonmatsu, 13 Miyoda, 14 Nishikawa,
15 Kitamachi, 16 Kawamata, 17 Marumori, 18 Funaoka Ohashi, 19 Senoue, 20 Yagita, 21 Kuroiwa,
22 Tomita, 23 Ota, 24 Odaka, 25 Asami, 26 Tsushima, 27 Ukedo, 28 Takase, 29 Haramachi,
30 Akanuma, 31 Watari.)

2 Available in English from: https://www.iaea.org/sites/default/files/23/06/fcp_final_report_2013-2022.pdf and in Japanesefrom https://www.iaea.org/sites/default/files/23/06/fcp_final_report_2013-2022_japanese.pdf

13

FIG. 4b: Absolute (top) and normalized (bottom) activity concentration of dissolved 137Cs in water ofrivers of the Fukushima Prefecture from 2011–2021 [17]. The red line in the upper figure marks the
WHO guidance level of 10 Bq/L for 137Cs in drinking water [18]. (The bottom of the figure on thenormalized concentration of dissolved 137Cs in river water was kindly provided by the Fukushima
Prefecture). Image credit: Fukushima Prefecture3.
(The numbers represent the following rivers: 1 Mizusakai River, 2 Kuchibuto River, Upstream,
3 Kuchibuto River Midstream, 4 Kuchibuto River Downstream, 5 Fushiguro, 6 Iwanuma, 7 Mano,
8 Ojimadazeki, 9 Matsubara, 10 Onahama, 11 Tsukidate, 12 Nihonmatsu, 13 Miyoda, 14 Nishikawa,
15 Kitamachi, 16 Kawamata, 17 Marumori, 18 Funaoka Ohashi, 19 Senoue, 20 Yagita, 21 Kuroiwa,
22 Tomita, 23 Ota, 24 Odaka, 25 Asami, 26 Tsushima, 27 Ukedo, 28 Takase, 29 Haramachi,
30 Akanuma, 31 Watari.)

3 Available in English from: https://www.iaea.org/sites/default/files/23/06/fcp_final_report_2013-2022.pdf and in Japanesefrom https://www.iaea.org/sites/default/files/23/06/fcp_final_report_2013-2022_japanese.pdf

14

Table 2: Effective half-lives of particulate and dissolved 137Cs in rivers of the Fukushima
Prefecture from 2012 to 2021 [16, 17]. The number of observations is given in brackets.
Form of Cs137
Particulate
Dissolved

Effective half-life of Cs-137 in the period 2012-2021 (years)
AbukumaAffluents ofRivers in
Mean of all
River
Abukuma
Hamadori
rivers3.7 (6)
3.2 (11)
3.1(12)3.2 (29)
2.8 (6)
3.0 (10)2.7 (11)
2.8 (27)

FIG. 5: Activity concentration of particulate and dissolved 137Cs from 2011 to 2021 in the Hiso and the
Wariki River. Image credit: Fukushima Prefecture (reproduced from Ref. [21]. (Please note: Somecircles are on top of each other due to datapoints (open circles) being on top of one another andsubsequently look like filled circles.).

4.2.2.

Leaching of 137Cs from litter and concentrations of dissolved 137Cs in run-off
water

A seasonal variation of dissolved 137Cs in river water with a maximum in summer and minimumin winter was found by Nakanishi and Sakuma [19]. It is suggested that the release of 137Cs
during decomposition of litter in flooded areas is an important source of dissolved 137Cs inrivers. The seasonal effect was less pronounced towards the end of the observation period(2015–2018).
These results are supported by another study by Tsuji et al [22] where the normalized
concentrations of dissolved 137Cs4 in 66 rivers of East Japan were determined. It was found that4

Normalized concentration of dissolved 137Cs: Ratio of dissolved 137Cs in river water and the average
Cs-deposition in the catchment area [m²/L].

137

15

the normalized concentrations of dissolved 137Cs decreased with increasing coverage of forest
in the catchment areas, whereas it increased with larger fractions of built-up areas. It is
postulated that high concentrations of potassium and dissolved organic carbon in urban areas
inhibit the sorption of 137Cs to soil particles found in runoff water [22].
Furthermore, it was found that the normalized concentration of dissolved 137Cs increased withthe topographical wetness index TWI5 [22]. TWI is high for flat areas, because run-off is low,
and the periods of wetted surfaces are longer than on slopes. Forested areas are mainly on slopes
and therefore have a lower TWI; this is consistent with the finding on the negative correlation
between dissolved 137Cs in water and the coverage of forest in the catchment area.
The leaching of 137Cs from litter in Fukushima broadleaf forests were studied by Sakakibara
et al [23], the key findings are:⎯⎯

The amount of 137Cs leached from litter increased with increasing contact area and time
between litter and rainwater;
The concentration of dissolved 137Cs in run-off water increased with increasing amountof rainfall, which also increased contact area and time between litter and water.

In conclusion, the results given in Refs [19, 22, 23] consistently indicate a relationship between
the leaching of 137Cs from litter and the levels of dissolved 137Cs in run-off water. However,these findings need to be put in context with the contributions of dissolved 137Cs and of 137Cs
in suspended sediments to the total 137Cs activity in river water. As both Figures 4 and 5 show,
the by far dominating fraction of 137Cs in river water is bound to suspended sediments.
4.2.3.

Dynamic of 137Cs in four headwater catchments

The time-dependence of the concentrations of dissolved 137Cs and of 137Cs bound to suspended
sediments and coarse organic matter is studied in four headwater catchments of the Fukushima
Prefecture from 2011 to 2016 by Iwagami et al [24].
The dynamics of the activity concentration of 137Cs in run-off water was approximated byexponential functions with one or two components. The periods of the first 200 days and theperiod from 2012 to 2016 were considered separately.
The fastest decline was observed for dissolved 137Cs, during the period June to December 2011
with an effective half-life Teff,1 ranging from 44 to 77 d (Table 3).
In the second phase, the decline was differentiated between dissolved 137Cs, 137Cs bound tosuspended sediments and 137Cs bound to coarse organic matter:

⎯
⎯
⎯

5

Dissolved 137Cs declined according to an effective half-life in the range of 0.89-5.3 years;
Caesium-137 bound to coarse organic matter declined according to Teff,2 of 0.82–2.1
years.
The largest fraction of 137Cs in run-off water was bound to suspended sediments.
The concentration of this fraction varied widely with reported 𝑇eff values ranging from
1.6–22 years.

The topographical wetness index is defined as: TWI= ln(Area of the watershed area / [tan(slope)]).

16

Table 3: Effective half-lives of 137Cs activity concentration in water discharged from headwater
catchment for different forms of 137Cs [24, 25].
Phase

June 2011 to
December 2011

Catchmentarea

Form of 137Cs

Koutaishia
Iboishic
Ishidairad
Koutaishia

Dissolved
Dissolved
Dissolved
Dissolved
Suspended sediment
Dissolved
Coarse organic matter
Suspended sediment
Dissolved
Coarse organic matter
Suspended sediment
Dissolved
Coarse organic matter
Suspended sediment

Setohachib

January 2012 toNovember 2016

Iboishic

Ishidairad

Effective half-life
Teff,1
Teff,2(June to December 2011)(2012 to 2016)77 days
44 days
44 days
2.2 y
22 y
5.3 y
2.1 y
2.5 y
0.98 y0.82 y4.6 y0.89 y
1.0 y
1.6 y

a

Koutaishi: cedar forest 99%, grassland 1%, b Setohachi: cedar forest 100%); c Iboishi: cedar and deciduous forest
76%, grassland 23%, d Ishidaira: cedar forest 81%, grassland 19%.

In general, the decline of 137Cs in run-off water was faster in catchments with a higher fractionof pasture than that in forested catchments. This observation agrees with the findings reported
in Ref. [26], where a more rapid decrease of the 137Cs activity concentration in grass comparedwith litter was observed.
4.3. RADIOCAESIUM OF CAESIUM-137 IN SUSPENDED SEDIMENTS
4.3.1.

Interaction of flow rate, concentration of suspended sediment and Cs-levels of
suspended sediments

The relationships between water level, concentration of suspended sediments and the 137Cs
levels in suspended sediments were investigated in a study by Arai et al [27]. The study was
carried out in the catchment of the Hirose River, where water samples were taken near the
confluence of the Hirose and Abukuma River.
The study is based on measurements of: (i) particulate 137Cs in river water and in suspended
sediments; (ii) the total organic carbon (TOC) in water and in suspended sediments; and (iii) the137
Cs and TOC levels in adjacent forest soil, forest litter, riverbank soil and river sediments.
Water samples were taken under base-flow conditions and under high flow conditions6 during
and after typhoons. The sampling was carried out from September 2017 to October 2019.
In addition, this study determined the fractions of forest soils, forest litter, forest soils, and river
sediments in suspended sediments based on the concentrations of 137Cs, TOC, and the6Base flow conditions are defined, if the sampling of water was carried out at least 2 days after the last
precipitation, TSS concentration varied from 1.5 to 4.2 mg/L.
Sampling under high flow conditions was carried out during and after typhoons, SS concentrations varied from
5 to 930 mg/L.

17

13C-signature7 in these media. The fractions were estimated by means of a mixing model forbase flow and high flow conditions.
The results are shown in Figure 6. With increasing concentration of suspended sediments inriver water:

⎯
⎯
⎯
⎯
⎯

The concentration of particulate 137Cs in river water increased;
The concentration of organic matter in water increased;
The concentration of 137Cs in suspended sediment declined;
The total organic carbon in suspended sediments decreased; andThe 13C-level in suspended sediments decreased.

During high flow conditions, the concentration of suspended sediments in river water was
higher than under base-flow conditions, as resuspension of bottom sediments becomes more
and more important with increasing water levels.
4.3.2.

Origin of suspended sediments in rivers during high water periods

The 13C-signatures, the TOC concentration in water and the 137Cs activity concentration insuspended sediments were used to determine the source of carbon in a sample. The
13C-signatures in different media and forest soil samples indicate the origin of the increased
amounts of suspended matter in river water. Table 4 summarizes the 13C-signatures, the 137Csconcentrations and the TOC concentrations in various samples in the study site. The
13C-signatures for material from the river vary from -25.4 to -26.4 ‰, whereas the13C-signatures in forest soil and litter varies from-26.4 to -30.0 ‰. This means, there is a clear
difference of the 13C-signatures among river sediments, riverbank soil, forest soil, and forest
litter.
The decline of the 13C signature with increasing concentrations of SS in water — and with atendency to increasing flow velocities — indicates that the relative contribution of forest soil
and forest litter declines. At the same time, the relative contribution of riverbank soils and river
sediments to SS increases with increasing concentrations of SS in river water. A simulation of
the different contributors to SS confirms this hypothesis:⎯⎯

Under base flow conditions forest soil contributes nearly 70% to the SS. Riverbank soil
and river sediments together contributed approximately 7%;
At high flow, the absolute TOC concentration in river water increased. As a result, therelative contribution of forest soil to SS decreased to 48%, and the input of both riverbank
soil and river sediments to SS increased to about 50%.

13C-signature: 13C is a natural stable carbon isotope, about 1.1% of the global carbon is 13C. The 3C signature
quantifies the deviation of the 13C/12C-ratio from Vienna PeeDee Belemnite (VPDB) standard [28] in anenvironmental sample in permille. The 3C signature is calculated from the concentrations of 13C and 12C in thesamples and in the VPDB standard according to:13C = [(13Csample/12Csample - 13Cstandard/12Cstandard)/ 13Cstandard/12Cstandard)] × 1000.
The depletion of 13C in organic material is due to the higher atomic mass of 13C compared to 12C, this facilitates
the uptake of 12CO2 by plants during the photosynthesis, and it causes the depletion of 13C in plant material.
718

FIG. 6: Dependence of particulate 137Cs, POC (particulate organic matter), TOC (total organic matter),and 13C on the concentration of TSS (total suspended sediment) in water. The average value andstandard deviation under the base-TSS-load conditions (black squares) and all the data measured underhigh-TSS load conditions (orange circles) are shown. For POC, TOC, and 13C, measured andestimated values are shown separately for each of the river conditions (grey for estimated and blue andorange for measured values, and squares for the base- and circles for the high-TSS-load conditions).
(a) Particulate 137Cs concentration in river water; (b) POC content; (c) 137Cs concentration of TSS;(d) TOC concentration of TSS; (e) 13C values in TSS. The shaded areas represent the 95% confidence
intervals. Image credit: Fukushima Prefecture (Figure from Ref. [27]).

Table 4: 13C-signatures, 137Cs activity concentration, total organic carbon and for river andforest samples [27]Material

13C signature(‰)

Number ofsamplesCs-137 activity
concentration(Bq/kg)Number ofsamples

Total organiccarbon(mgC/mg)

Numberofsamples

Forest soil

-26.9±0.6125400±1600120.11±0.021

12

Forest litter-30.0±0.516240±150160.47±0.011

16Riverbank soil

-26.4±0.815470±530460.018±0.015

15River sediment-25.4±0.8

21110±110175

0.001±0.001

21

19

4.3.3.

Normalized 137Cs activity concentration in suspended sediments

The long-term behaviour of radiocaesium in catchments is essential for the evaluation of
possible impacts of radiocaesium on water supply, agriculture, and leisure activities.
Intensive measurements of radiocaesium were carried out in rivers in Fukushima for 30
monitoring points [15]. For comparing the dynamic of radiocaesium, the 137Cs activity
concentrations were normalized to the mean deposition density in the catchment related to theriver basin [15]. The underlying data for the assessment are summarized in Appendix II below.
The time-dependence of the activity concentrations were approximated by exponentialfunctions with two components. The results are shown in Figure 7. The data cover the period
from 2011 to 2016. The post-deposition-decline of particulate 137Cs concentrations ischaracterized by an initial rapid decline in the first year after the accident, which slows down
during the following years.
For six monitoring sites in the Abukuma River system, a more detailed study has been carriedout to estimate the 137Cs loss from the catchment areas. For each of the catchments considered,the decline of the normalized particulate 137Cs activity concentration C’(t) was approximatedby single exponential functions for the phases June 2011 to March 2012 and April 2012 toAugust 2015 respectively:⎯⎯

For the period June 2011 to March 2012:
For the period April 2012 to August 2015:

𝐶1′ (𝑡) = 𝑎1 ∙ 𝑒 −𝜆1∙𝑡 (Eq. 1a);𝐶2′ (𝑡) = 𝑎2 ∙ 𝑒 −𝜆2∙𝑡 (Eq. 1b),where a1 and a2 are fitting parameters for period 1 and 2, respectively, and 1, and 2 describe
the reduction rate of 137Cs in suspended sediments of the rivers considered.
The values for the parameter an and Teff,n are given in Table 5 (Teff,n corresponds to n in Eqs 1a
and 1b according to: Teff,n= ln2/n). The 137Cs activity concentrations in suspended sediments
decline rapidly. In the first period, the normalized 137Cs concentrations in suspended sediments
decrease according to effective half-lives in the range of 0.3 to 1.6 years, in the second phasethe decline rate slows down, it is equivalent to half-lives of 1.4 to 2.7 years.
Table 5 also includes the half-lives of 137Cs in suspended sediments measured at 24 other sites
in the period 2012–2016. Due to later start of the measurements, the short-term component of
the decline could not be determined, and the half-lives are given for the second component of
the decline only. For these sites, the estimated half-lives of the 137Cs concentration in suspended
sediments vary from 1.1 to 16 years.
4.3.4.

Land-use and 137Cs-loss with surface run-off

Additionally, in the Upper Kuchibuto catchment, the relationship of the land-use and the lossof 137Cs with surface run-off [15]. The land-use was classified into forest – which are thought
to have low run-off — and areas with Paddies, Farmland, and Urban use (PFU) with a higher
run-off. Results are shown in Figure 8. Since immediately after the accident the loss of 137Cs
activity with surface run-off is more pronounced, the periods June 2011 to February 2012
(upper part) and March 2012 onwards are considered separately.

20

FIG. 7: Time-dependence of particulate 137Cs in river water normalized to the deposition density in the related catchments for rivers of: (A) Abukuma mainstream;(B) Abukuma tributaries (West); (C) Abukuma tributaries (East); and (D) coastal catchments (Hamadori district). In plot C, sites 1_Miz and 2_KU were excluded
from the analysis due to ongoing decontamination activities. Image credit: Fukushima Prefecture (Figure from Ref. [15]). The underlying data on the 137Cs activity
concentrations in suspended sediments for Figure 7 are summarized in Appendix II below.

21

Table 5: Parameters for the exponential functions to describe the time-dependence of thenormalized activity concentration of 137Cs in suspended sediments for the periods June 2011 toMarch 2012 and April 2012 to August 2015 [15], the measurements for sites 7–30 started in
April 2012 only.
Site name1 Mizusakai
2 Kuchibuto_Upper
3 Kuchibuto_Middle
4 Kuchibuto_Down
5 Fushiguro
6 Iwanuma
7 Mano8 Ojimadazeki
9 Matsubara
10 Onahama
11 Tsukidate
12 Nihonmatsu
13 Miyota
14 Nishikawa
15 Kitamachi
16 Kawamata
17 Marumori
18 Funaoka-ohashi
19 Senoue
20 Yagita
21 Kuroiwa
22 Tomita
23 Ota24 Odaka
25 Asami
26 Tsushima
27 Ukedo
28 Takase
29 Haramachi
30 Akanuma

22

Exponential function describing the decline
from June 2011 to March 2012a1
Teff,1 (y)
0.64
1.6
0.79
0.37
0.74
0.33
0.64
0.75
0.96
0.18
0.92
0.22
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–

Exponential function describing the decline
from April 2012 to August 2015a2
Teff,2 (y)
0.36
2.7
0.21
2.0
0.26
1.6
0.36
1.4
0.04
1.8
0.08
1.5
0.040
8.2
0.020
4.6
0.022
3.7
0.060
2.1
0.117
1.1
0.128
1.6
0.039
2.9
0.032
2.5
0.117
1.5
0.118
1.1
0.063
1.8
–
–
0.133
2.4
0.060
16.4
0.132
1.3
0.286
1.5
0.031
3.8
0.021
11.4
0.033
2.1
0.088
1.7
0.037
2.8
0.070
1.7
0.042
3.0
0.050
2.0

FIG. 8: Relationship between the coverage of the catchment with Paddies, Farmland, and Urban areas (PFU) and the scaling factor a, the decline rate  of thenormalized 137Cs-activity concentration in suspended sediments, and the total loss of 137Cs from the catchment with surface run-off. Image credit: Fukushima
Prefecture (Figure from Ref. [15]).
23

The relationships of the coverage of the catchment with paddies, farmland, and urban areas(PFU) with the following parameters have been plotted in Figure 8 for the periods June 2011
to February 2012 and from March 2012 to August 2015:⎯⎯⎯

The reduction rates  of the normalized 137Cs activity concentration in suspended
sediments (Eq. 1) increases with increasing PFU-coverage;
The scaling factors a (Eq. 1) increases with increasing PFU-coverage;
The total loss of 137Cs from the catchment increases with increasing PFU-coverage.

The data clearly indicate that surface run-off from catchments increases with increasing
fractions of PFU. These relationships are more pronounced in the first period (June 2011 to
February 2012) compared to the time following. This observation is confirmed by thecomparison of the 137Cs flux from forests and from PFU (Figure 9) for the Iwanuma catchment[15]. It should be noted that the 1st period covers only 9 months, whereas the second period
covers about 3.5 years:⎯⎯

In the first period, the total 137C flux from forests is about a factor of 3-4 lower than from
PFU, although the area covered by forests is a factor of 2 larger than for PFU;
In the second period, the 137C flux from forests is similar to that in the first period.
However, the 137C flux from PFU is lower than in the first period by a factor of 2.

The total 137C inventory of the Iwanuma catchment is about 470 TBq (Table 6). The total runoff
from forests and PFU is about 10 TBq in the period 2011–2015, which is about 2% of the total
inventory. During the same period, the reduction of the inventory by radioactive decay is about
9%. However, it is important to note that runoff can locally lead to significant changes in 137C
activity concentrations in soils and sediments.
4.3.5.

Flux of 137Cs with suspended sediments

For the monitoring stations in Table 6, the flux of 137Cs during the observation period wasestimated. The normalized 137Cs activity concentrations in suspended matter are the basis forquantifying the total loss of 137Cs from catchments via surface run-off and the subsequenttransport with sediments in rivers. Additionally, the following quantities were considered toestimate the flux of 137Cs from the catchments:

⎯
⎯
⎯
⎯

Average initial deposition in the catchment areas considered as of June 2011;
Hydrological data as flowrate and turbidity;
Precipitation;
Topographical data including elevation and land-use data.

The monthly fluxes of suspended sediments and of 137Cs in the rivers are calculated monthly
and integrated over the total observation period [15]. These analyses have been carried out for
30 monitoring sites of the Fukushima prefecture. The results are given in Table 6. The
underlying data for Table 6 are summarized in Appendix III.
In general, the losses of 137Cs activity from the catchments due to run-off and river transport
are low. In the 1st year, the loss varies 0.13–1.7%, in the period from June 2011 to August 2015,
the total loss ranges from 0.1–4.3%. In the same periods, 137Cs activity is reduced due tophysical decay by 1.7% and 9.2% respectively; for the investigated catchments, the activity lossof 137Cs and 134Cs due to physical decay is more important than run-off. More than 95% of the137
Cs is lost in particulate form.
24

FIG. 9: Flux of particulate 137Cs from forests and PFU from observed in the catchment Iwanuma(Forest: 62%, PFU 30%). Image credit: Fukushima Prefecture [15].

Table 6: Characteristics of the catchments included in the study on the loss of 137Cs [15].
Site name1 Mizusakai
2 Kuchibuto-up
3 Kuchibuto-mid
4 Kuchibuto-down
5 Fushiguro
6 Iwanuma
7 Mano8 Ojimadazeki
9 Matsubara
10 Onahama
11 Tsukidate
12 Nihonmatsu*
13 Miyota
14 Nishikawa
15 Kitamachi
16 Kawamata
17 Marumori*
18 Funaoka-ohashi#
19 Senoue
20 Yagita
21 Kuroiwa
22 Tomita
23 Ota24 Odaka
25 Asami
26 Tsushima
27 Ukedo
28 Takase
29 Haramachi
30 Akanuma

Particulate
Cs-137 loss
Particulate
Cs-137 loss from thefraction of
from thefraction of CsCatchment Averagecatchment (%)
Cs-137 flux (%) catchment (%) 137 flux (%)
area
deposition(km²)(kBq/m²) 6/2011 to 6/2011 to
6/2011 to
10/2012 to
10/2012 to
3/20128/20158/20158/20158/2015
7.5
745
0.13
0.4
97.2
0.24
98.3
21.4
477
0.39
1.1
98.5
0.65
98.9
62.8
357
0.4
1.0
99.6
0.57
99.7
135
269
0.64
1.4
99.7
0.62
99.7
3640
95.9
1.7
3.3
98.7
1.09
97.5
5310
88.4
1.6
2.7
96.5
0.78
96.6
75.6
499
0.10
90.0
111
406
0.11
89.3
571
40.0
0.09
69.6
70.1
38.8
0.42
66.7
83.6
223
0.40
99.2
2380
81.8
1290
74.1
0.64
96.4
290
132
0.30
97.6
35.8
565
0.37
93.4
56.6
229
0.19
97.4
4120
105
20.2
775
313
41.9
0.59
94.3
185
52.7
1.04
92.1
2920
103
1.01
98.6
72.6
98.5
4.3
98.3
49.9
1770
0.03
82.2
50.3
724
0.08
83.4
25.8
194
0.10
91.4
25.4
952
0.10
98.0
153
2570
0.23
87.5
264
726
0.42
99.5
200
964
0.26
98.5
242
52.6
0.12
92.9

* Not included in the analysis since too few turbidity data were available.
# Not included in the analysis because only data for dissolved 137Cs were available.

25

4.4. MODELLING THE CONCENTRATIONS OF DISSOLVED AND PARTICULATECAESIUM-137 IN RIVER WATER
The concentrations of dissolved and particulate 137Cs in rivers of the Fukushima were modelled
by application of the TODAM8 model. The model was designed for estimating the transport ofradionuclides in rivers. The model requires data on water flow, topography, land use and grainsize distribution. In the Fukushima Prefecture, it was applied to estimate the transport ofdissolved and particulate 137Cs downstream the Hirose River. Within the studied area, the rivers
Takane, Nuno, Ishida, and Oguni join the Hirose River.
In Figure 10, the measured and predicted activity concentrations of particulate and dissolved
137
Cs in the Hirose River are shown. The simulation was performed for a relatively low
flowrate. The activity concentrations of particulate and dissolved 137Cs in water are the resultof the interaction of water composition, silt, clay and sand content of the suspended sediments,
turbidity, and flow rate. The 137Cs concentrations in suspended sediments are of the order ofseveral thousand Bq/kg, the concentration of dissolved 137Cs is in the range 1–5 Bq/m³. Despite
this complexity, measurements and prediction agree reasonably well. The understanding of the137
Cs transport supports planning of remediation measures in rivers, the dislocation of riverbed
sediments and the persistence of countermeasures.

FIG. 10: Comparison of measured concentrations for particulate and dissolved 137Cs in the Hirose River
with simulations using the TODAM model. Image credit: Fukushima Prefecture.

8

The TODAM model (Time-dependent, One-dimensional Degradation And Migration) was developed [29]. Thismodel has been applied in many countries to simulate the transport of radionuclides in freshwater systems as e.g.
in the framework of remediation projects in Hanford (Washington, USA), Chornobyl (Ukraine), and Mayak
(Russian Federation).

26

4.5. COMPARISON OF JAPANESE AND INTERNATIONAL EXPERIENCE ON THE
DYNAMIC OF CAESIUM-137 IN RIVERS
Effective half-lives of 137Cs in river water

4.5.1.

Following the accident in the Chornobyl Nuclear Power Plant in 1986, freshwater bodies allover Europe have been monitored for 137Cs in water and in suspended and bottom sediments[30]. However, 137Cs activity concentrations in different water bodies are not directlycomparable. The 137Cs concentrations in the water bodies and their time-dependence are theresults of an interaction of the deposition density, the catchment area, size of the water body,
precipitation, rainfall intensity, slope, and land-use.
To facilitate the comparison of the behaviour of 137Cs in freshwater systems, the timedependence of radionuclides in sediments, suspended sediments or water is approximated by
an exponential function or a sum of exponential functions. If the available data allow, theactivity concentrations may be normalized to the average deposition in the catchment tofacilitate the comparison of different rivers and catchments:
𝐶𝑤 (𝑡) = 𝐶0 ∙ ∑𝑛1 𝑎𝑛 ∙ 𝑒 −𝜆n ∙𝑡
𝐶

′ (𝑡)
𝐶w
= 𝐷0 ∙ ∑𝑛1 𝑎𝑛 ∙ 𝑒 −𝜆n ∙𝑡
0(Eq. 2a)(Eq. 2b)where:𝐶𝑤 (𝑡) is the time-dependent activity concentration in sediments (Bq/kg) or water (Bq/L);′ (𝑡)𝐶w
is the time-dependent normalized activity concentration in sediments/water (m²/kg or
m²/L);
C0 is the initial concentration in sediments/water (Bq/kg) or water (Bq/L);
D0 is the initial average deposition in the catchment (Bq/m²);
An is the weighting factor for the exponential function n;
n is the decline rate of the exponential function n (a-1) (corresponding half-live T½,n=ln(2)/ n).
The parameters of Eqs 2a and 2b, which reflect global experience, as well as those determinedin studies conducted in Fukushima Prefecture after 2011, are compiled in Table AI.1 (Appendix
I, with all underlying references). However, not all parameters included in Eqs 2a and 2b could
be determined in all studies.
In the studies, the number of exponential functions identified varies, depending on theobservation period, and the start of the observation period after the contamination event. In
long-term studies, starting immediately after the deposition, a typical pattern of the long-termdecline of radiocaesium in water is characterized by 3 phases. However, in some cases, theobservations started too late after the deposition, then the initial concentration in water could
not be determined and the rapid decline immediately after the deposition was not covered by
the observation period. In other case, the observation period was not long enough to identify
the long-term component of the decline.
From the data compiled in Table I.1 (Appendix I), the following trends can be extracted:
General aspects:⎯

As expected, immediately after the deposition, the maximum level of 137Cs in river water
is observed.
27

⎯
⎯

Most data are for suspended sediments. However, the effective half-lives observed forparticulate and dissolved 137Cs are in the same range.
By and large, the time trends observed in Japan and in other parts of the world agree
reasonably well. The general pattern of the decline is quite similar in both regions.

Initial decline:⎯⎯

Initially, concentrations in water decrease rapidly, with time the decrease slows down.
• In European rivers, immediately after deposition during a period of about 2–3 weeks,a decline of the 137Cs according to an effective half-life of 5 days was observed.
• In measurements of 137Cs in river water, starting several days after deposition, effective
half-lives in the range of 20–50 days were observed.
• In some cases, the measurements started later (in 1987 following the Chernobyl
accident, in 2012 following the accident in FDNPP). Then the very rapid immediate
decline of concentrations is no longer reflected in the first component. In such cases,
effective half-lives of 70–270 days were found, in one case 1.6 y were observed.
The results achieved in the Fukushima Prefecture agree well with the global experience.

Decline within an observation period of 5–15 years:⎯⎯

Many data sets do not include the initial phase with the fast decline; most data are
available for the second component which covers observation periods of 5–15 years
starting several months after radionuclide deposition.
• For Ukrainian rivers, the effective half-lives found are in the range from 2.0–6.5 years.
• In two Finnish rivers, effective half-lives of 3.5 and 6 years were observed.
• In the Iput River (Russia), an effective half-life of 1.3 years was observed in the period
1987–1991.
• For the Fukushima Prefecture, values for effective half-lives from 48 data sets areavailable ranging from 0.7–16 years. Three values were below 1 year, and three values
were above 5 years. Fourty-two values were in the range from 1.1–4.6 years.
The results from the Fukushima Prefecture agree very well with the effective half-lives
observed in Ukraine, Russia, and Finland.

Long-term decline:⎯⎯

4.5.2.

If the observation period is long enough, in some cases a third phase can be identified.
However, quantifying a third decline component requires observation times of at least
15 years, since the overall contribution of a third exponential term is very small. So far,in the studies carried out in the Fukushima Prefecture, such long observation periods are
not possible.
In an analysis of the time dependence of 137Cs in water of 25 rivers in Europe and West
Asia after the Chernobyl accident, a third component with an effective half-life of
16 years was identified. The contribution to the overall decline of this component was
only 0.5% and the relevance in practice is of minor importance.
Loss of 137Cs from catchments

As was the case for the releases during the accident in FDNPP, the releases from the Chernobyl
accident occurred within a short time. For estimating the loss of activity from a catchment, in
Ref. [31] a transfer function has been defined, which describes the loss rate of activity depositedin a catchment by run-off processes as function of time. In agreement with the studies carried
28

out in the Fukushima Prefecture, the run-off depends on specific circumstances as thecharacteristics of the catchment, the radionuclide and the quantity considered (run-off ofdissolved or particle-bound radionuclides, total run-off). The transfer function consists of
2 components:
𝑓(𝑡) = 𝑓1 ∙ λ1 ∙ exp⁡[−(λ1 + λ𝑟 )⁡∙ 𝑡]+⁡𝑓2 ∙ λ2 ∙ exp⁡[−(λ2 + λ𝑟 )⁡∙ 𝑡](Eq. 3a)𝑓1 + 𝑓2 = 1(Eq. 3b)where:
f1 is the fraction of activity that is available for short-term (rapid) run-off;
f2 is the fraction of activity deposited which is subject to long-term run-off;1, 2, r, are the loss rates for the short- and the long-term components of run-off and thephysical decay respectively (a-1).
The parameters f1 and f2 and the loss rates 1 and 2 have been determined from wash-off
experiments and observations in the field.
Regarding total 137Cs-run-off, the parameter f1 covers a range of 0.2–7.4%. However, the upperbound of the range has been determined for experiments on small plots. For catchment areas,
for f1 a value of the order of a percent is given as a typical estimate for radiocaesium.
The loss rate for short-term wash-off 1 is estimated to be approximately 24 a-1, whichcorresponds to a half-life of about 10 days [31].
The long-term 137Cs -activity loss due to surface run-off is much less. The ranges for 2 for runoff of dissolved and particulate 137Cs are 0.00007–0.02 a-1 and 0.00009–0.1 a-1 respectively;
the values in the lower part of the range refer to flat terrains where the run-off is very low by
nature. Regarding the total loss due to run-off, the 2-values for 137Cs cover a wide range from
0.00004–0.01 a-1. For catchment areas, 2-values of less than 1% are given as a typical estimate
for radiocaesium [31]. The upper limit of 2 of 0.01 a-1 is lower than the activity loss due tophysical decay rate r of 0.023 a-1, i.e. the decline of the total 137Cs-inventory in a catchment
area is generally dominated by the radioactive decay.
These findings are in general agreements with the findings of the studies carried out in the
Fukushima Prefecture.

29

5.
5.1.

EXPERIENCE MADE DURING DECONTAMINATION WORKEFFECT OF DECONTAMINATION ACTIVITIES ON RIVERS AND
CATCHMENTS

In the upper part of the Kuchibuto River, from March 2013 to December 2015, a
decontamination project was implemented on an area of 1600 ha. The area is mainly used asforest (730 ha) and for agriculture (610 ha), 71 ha are covered by roads; the rest is used forresidential purposes. The decontamination work focused on removal of topsoil fromagricultural and washing of roads and paved areas. Most of the work was carried out from April
2014 to March 2015.
The loss of suspended sediments from the catchment before, during and after thedecontamination work is shown in Figure 11. Transport of suspended sediments increased
during decontamination work, and it declined after it was completed. However, aftertermination of the decontamination project, the sediment loss remained higher than before thedecontamination work.
The monthly loss of 137Cs as a percentage of the total 137Cs inventory from the upstream,
midstream and downstream Kuchibuto catchment is shown in Figure 12. The monthly losses
were highest immediately after the deposition. The monthly loss increased during thedecontamination work as the disturbance of the upper soil layer intensified erosion processes.
The area was hit by typhoons in September 2015 and 2016 that caused widespread flooding due
to heavy rains, which was reflected in an increase in monthly 137Cs losses in September 2015
and 2016. After decontamination was completed, 137Cs losses decreased.
During the decontamination work, the total loss of 137Cs from the catchment due to surface runoff is of the order of 0.03% per month and does not contribute significantly to the decrease of
the overall 137Cs inventory in the catchment, which is dominated by the radioactive decay(0.19% per month).
However, it is important to be aware that the loss is not homogeneous over the whole catchment.
In some areas the 137Cs loss may be considerable whereas other parts may not be affected byerosion at all. The same is true for the landscape element that receives the activity lost from the
upstream catchment. The total inventory of the receiving landscape element may not change
significantly, but locally, the activity concentration may be modified considerably.
5.2. DECONTAMINATION OF RIVERBEDS AND RIVERBANKS
Immediately after the accident, comprehensive decontamination activities were set up to reduce
activity and radiation levels in residential and public areas, and on agricultural land. For publicareas, focus was given to routes for children to schools and kindergartens, and to areas used for
leisure activities.

30

FIG. 11: Loss of suspended sediments from the Upper Kuchibuto catchment before, during, and after
the decontamination work. Image credit: Fukushima Prefecture [32].

FIG. 12: Monthly loss of 137Cs with suspended solids from the Kuchibuto catchment upstream,
midstream and downstream. Decontamination work was carried out from April 2014 to March 2015,
the decontamination intensity was highest from April 2014 to March 2015. Image credit: Fukushima
Prefecture (Figure created from data in Refs [15, 20]). The underlying data for this figure aresummarized in Appendix III.
31

For demonstrating the feasibility and for exploring the effectiveness of decontamination
measures, in terms of reduction of gamma-dose rates in air, three sites of the Fukushima
Prefecture were considered:⎯⎯⎯
5.2.1.

Kami-Oguni River: A path along the river is used as route to a school and for recreation.
Decontamination measures included pre-weeding and removal of sediments from theriver bottom. Additionally, vegetation and soil were removed from the river dikes
Figure 13. The decontamination activities were carried out from August to November
2014. Gamma-dose rate was reduced by about a factor of 2 [33].
Niida River Park: An area close to the river which is used for leisure purposes. Modelcalculations were carried out to estimate the possible reduction of gamma dose rates.
The Nature Park at the Mizunashi River in Minami-Soma city is used for leisure. The
effectiveness of decontamination measures was studied by means of model simulations.
Impact of typhoons and flood events on the persistence of decontamination

The Fukushima Prefecture is occasionally hit by typhoons which are associated with highrainfall, overflowing of rivers and floods. Such high-water events cause considerable
displacement of sediments and coarse material in the riverbeds; suspended sediments may also
deposit on adjacent flooded areas. Investigations to explore the impact of typhoons on thepersistence of decontamination measures were based on comprehensive measurements of
gamma-dose rates. Figure 14 shows the time-dependent gamma dose rate in air for the studied
area at the Kami-Oguni for the period from September 2014 to September 2015. A typhoon
occurred in August 2015.
The decrease of the gamma-dose rate in Figure 14 from February 2015 to September 2015
appears to indicate the impact of a typhoon. It is interesting to note that the displacement ofmaterials associated with the typhoon did not affect the effectiveness of the decontamination
work.
Another typhoon, called ‘Typhoon No. 19’, hit the Fukushima Prefecture in October 2019.
Gamma dose rates were comprehensively measured immediately after the typhoon in October
2019, and compared to those in January 2018 to estimate the impact of the typhoon. The results
are shown in Table 7. At all three sites, the gamma dose rates dropped. The 137Cs activity
concentration of the material carried with the flood water is noticeably lower than of theriverbed sediments before the flood. These observations are consistent with the results reported
by Evrard et al. [34] who measured 137Cs-activity concentrations in sediments and related
gamma dose rates in coastal rivers of the Fukushima Prefecture.
5.3. INTERNATIONAL EXPERIENCE ON REMEDIATION OF RIVERS
Since the early 1950s, experience has been gained world-wide in the management ofcontaminated rivers. Large amounts of radionuclides were released to the freshwater
environment from the nuclear facility in Mayak (Russian Federation) in the late 1940s and1950s [35]; this facility produced nuclear fuel and material for nuclear weapons since the late
1940s. Freshwater environments were also contaminated due to releases from the Hanford
facilities (USA) and from inappropriately stored liquid waste at the Hanford site since the mid1940s [36]. The Chernobyl accident in 1986 [37] caused a deposition of radionuclides on thefloodplain of the Prypiat River (Ukraine), which triggered a long-term input of radionuclides to
the Pripyat River.
In all cases, river water was used as drinking water, for irrigation, and for industrial purposes.
Decontamination measures were introduced to mitigate the radiological consequences
potentially arising from the contamination of freshwaters.
32

FIG. 13: The Kami-Oguni River before and during decontamination work in 2014. Image credit:
Fukushima Prefecture [33].

FIG. 14: Time-dependent −dose-rate at a demonstration site at the Kami-Oguni River for adecontaminated area(removal of weed, riverbed sediments, soil, and of vegetation from the dykes), a
flood occurred in August 2015. Image credit: Fukushima Prefecture [32].

Table 7: Comparison of average gamma dose rates before and after Typhoon No. 19. [32]Study sites
Kami-Oguni River
Niida River Park
Mizunashi River Park

Quantity
Average
Average
Average (range)

-dose rate at 1 m height (µSv/h)
Before Typhoon No. 19
After Typhoon No. 19(31 January 2018)(17 October 2019)
0.34
0.18
0.30
0.20
0.21 (0.07-0.42)
0.16 (0.02-0.32)

33

Freshwaters are dynamic systems with continuously changing conditions. Important factors are
the variations of water level and water flow, the input from the surrounding catchment, andsedimentation and resuspension processes. All these factors lead to varying concentrations ofradionuclides in dissolved and suspended form. Radionuclides in dissolved and particulate form
are continuously dislocated. Due to the dynamic nature of freshwaters, there are only limited
options for reducing activity levels in freshwaters and for interventions for reducing exposures
to people. The measures can be classified into two groups [38, 39], the most important are:Administrative measures:⎯⎯⎯

Restrictions on the use of drinking water for humans and livestock;
Restrictions on access to contaminated riverbanks;
Restrictions on fishing and freshwater fish consumptions/Technical measures:

⎯
⎯
⎯
⎯
⎯
5.3.1.

Water treatment in waterworks;
Modifying the water flow by the construction of dikes;
Implementing sedimentation traps to force sedimentation of suspended sediments;
Measures to reduce the radionuclide uptake by fish from water;
Removal of dissolved radionuclides by means of agents that adsorb radionuclides.
Administrative measures

Administrative measures were applied within the management of the contaminations of rivers
in Mayak, Chornobyl and Hanford [37, 40]. Experience from these sites show that suchmeasures are effective and easy to implement provided that sufficient water and fish can bemade available from other sources. This is easy to warrant for localized contaminations and forsmall water bodies, whereas it might be challenging for large-scale contamination that affect alarger group of population.
The radiological relevance of administrative measures in terms of reduction of doses depends
strongly on the living habits, such as withdrawal of drinking water, use of river water for
irrigation and consumption of local fish. An advantage of administrative measures is that
restrictions can, in principle, be easily lifted when activity concentrations in water, sediments,and fish have declined due to radioactive decay and other attenuation processes.
5.3.2.

Technical measures

In the early phase after the Chernobyl accident, charcoal and zeolite were applied in somewaterworks. The activity concentrations of 131I, 106Ru, 134Cs, 137Cs, and 90Sr were reduced byapproximately a factor of two, with charcoal being effective for iodine and ruthenium, andzeolite effective for caesium and strontium. The limited capacity of the sorbents has to beconsidered; a replacement with new sorbents would be necessary if the treatment is needed fora longer time [37].
Experience from the Chernobyl accident shows that technical measures implemented in
freshwater bodies to reduce activity levels in water and sediments need to be carefully planned
to consider the specific local hydrological conditions.
For reducing the transport of particulate radiocaesium, sediment traps were installed in the
Pripyat River. The effectiveness of this measure was very low, as a large fraction of caesium
34was in dissolved form which cannot be intercepted. Furthermore, the flow rates were too highto intercept small, suspended particles. However, it was found that the Kiev reservoir and deep
reservoirs in the Fukushima Prefecture along the rivers Ota (Yokokawa Dam), Mizunashi,(Takanokura Dam), Ukedo (Ogaki Dam), and Kuma (Sakashita Dam) act as sediment traps[41, 42]. The low flowrate in dams favours the sedimentation of particulates. This is a general
phenomenon which caused an effective sedimentation of radiocaesium in calm waters, such as
lakes and reservoirs.
On smaller rivers in the Chornobyl region, about 130 dikes containing zeolite were installed forabsorbing dissolved radionuclides [43]. The effectiveness was low, with only 5–10% of 90Sr
and 137Cs being removed. Due to the saturation of the sorbents, this low effectiveness declined
within a relatively short time; this measure is therefore not sustainable. Filtering of water
through reed beds to remove 137Cs and 90Sr was considered as a potential option; however, it isa cumbersome procedure and the application for larger areas is unlikely [43].
Depending on the local conditions, hydrological measures may prevent the dispersion ofradionuclides from contaminated land with water. In 1993, the Pripyat River was separated
from the highly contaminated Prypiat flood plain by a dike constructed on the left bank of theriver. This measure prevented the run-off of radionuclides from the highly contaminatedfloodplain to the Prypiat River [41]. This measure was technically feasible, as the area aroundthe Chornobyl NPP is flat. Such hydrological measures in mountainous terrains as found in the
Fukushima Prefecture, if technically feasible at all, may be much more complicated and costly.
In 18 Swedish lakes, the application of lime had no influence the 137Cs levels in freshwater fish[44]. The antagonism of caesium and potassium was tested in 13 Swedish lakes by applying
potash. However, the results do not allow to draw final conclusions, as the water turnover ofthe lake was too high to maintain sufficiently high levels of potassium concentrations in thelake water.
The application of potassium chloride to Lake Svyatoe (Belarus) with low natural potassium
concentrations and a lower water turnover, leading to a longer residence time of the water inthe lake, was more successful. After potassium application of 0.05 kg/m² to the lake surface in
1998, the 137Cs activity concentrations in large perch were reduced by approximately a factorof 3 (see Figure 15 below) [45]. Model calculations indicated that the reduced 137Cs levels inlarge perch would be reduced for about 15 years after the potassium application. However,application of potassium led to increased radiocaesium activity concentration in water due tocompetition with K in sediments, which could affect its use for drinking or irrigation.
Following the Chernobyl accident, numerous countermeasures were tested and implemented toprevent the input of run-off water to freshwater bodies. In general, the initial expectations ofsuch measures were not met, as it is complicated to control the dispersion of material in dynamic
systems as river. Engineering measures are costly and often difficult to implement; moreover,
the overall impact on public doses in the affected countries were low [37]. In terms of reducing
exposures to the public, restrictions on drinking water abstraction and fishing were mosteffective.

35

FIG. 15: Activity concentration of 137Cs in perch from the potassium application in 1998 to 2013. The
expected decrease in the absence of countermeasures is shown as well, an effective half-life of 20 years
has been assumed [45].

36

6.

MICRO PARTICLES CONTAINING CAESIUM-137

6.1. GENERAL INFORMATION ON MICROPARTICLESIn several investigations carried out in the Fukushima Prefecture, a kind of glassy particles
containing radiocaesium were found by autoradiography methods in various materials such as
air filters, house dust, soils, plant leaves near the accident site, agriculture materials, feathers ofbirds, and river water (see e.g. Refs [46–49]). The particles are usually called CaesiumMicroparticles (CsMPs). These particles were released from the reactors and dispersed in theatmosphere. So far, most CsMPs have been found relatively close to the reactors, but some werealso detected several hundred kilometres away from FDNPP [47].
Studies were carried out to investigate the chemical and isotopic compositions of the CsMPs,
to identify the likely sources of the CsMPs and the processes generating CsMPs during theaccident. Main elements of CsMPs are Si, Fe, Zn, Cs, and O. Two types of particles have been
identified, called Type A and Type B particles [48, 50]:⎯⎯

Type A particles are almost spherical, the diameter is typically less than 5 µm. Type A
particles originate from silicate glass. The activity is several Bq 137Cs per particle. The
134
Cs/137Cs ratio is above 1, which reflects the fuel burn-up at the time of the accident inUnits 2 and 3 of FDNPP. Therefore, it is thought that Type A particles originate from
Units 2 and 3.
Type B particles have various shapes, with diameters of a few to up to 400 µm. These
particles appear to originate from fibre silicate, which is an insulation material used in thereactor. The activity is in the range of 30–19 000 Bq. The 134Cs/137Cs ratio is lower than 1.
Type B particles are associated with Unit 1 of FDNPP.

Such caesium-microparticles (Cs-MPs) degrade slowly. A solubility experiment using a CsMP
with a radius of approximately 1 µm was conducted [51]. Seawater and pure water were usedas solvents. The dissolution rate in seawater was about a factor of ten higher than in pure water.
For this experiment (given in Ref. [48]), a lifetime for this particle of less than 10 years inseawater has been estimated. In pure water, the lifetime is expected to be much higher than 10
years, so the results indicate a low solubility and a high persistence. Investigations in soil
samples collected between 2011 and 2017 in the vicinity of FDNPP [52] indicate that 2–80%
of the radiocaesium in soil may be associated with such particles.
6.2.

CsMPs FOUND IN SUSPENDED SEDIMENTS OF THE HAMADORI RIVER

During investigations by Fukushima Prefecture on 137Cs in suspended sediments at amonitoring point of the Hamadori River in October 2018, a sample with an exceptionally high137
Cs concentration was taken. The concentration was about a factor of 5 higher than in othersamples taken in the same period (see Figure 16 below). The enhanced 137Cs-activity in thesample of suspended sediments was associated with the presence of radiocaesium microparticle(CsMP).
Characteristics of CsMPs found in the Kuchibuto River during campaigns carried out from 2011
to 2016 (see Table 8 below) were compiled by Miura et al [53]. The distribution coefficients,
Kd for 137Cs in the suspended sediment samples were calculated based on the 137Cs activity inthe sample excluding and including the activity of the CsMP. In all cases, the Kd-value basedon the total activity (including the CsMP) is higher, which indicates the low solubility of theCsMPs.

37

FIG. 16: Time dependent 137Cs activity concentration in suspended sediments at a monitoring station of
the Hamadori River, one sample has an exceptionally high 137Cs concentration. Image credit:
Fukushima Prefecture.

Table 8: Concentrations of 137Cs in CsMPs collected in the Kuchibuto River; the number of
CsMPs, and Kd-values with or without CsMP in the solid phase [53].
Sampling date
31 July 2011
3 August 2012
3 May 2014
22 November 2014
22 November 2015
1 April 2016

Numberof CsMPs

Cs-137 in CsMPs
(Bq)

17
1
6
4
5
3

4.3
0.11
4.1
0.77
2.3
0.48

Fraction of
CsMPs on filter
(%)
15
1.3
36
67
66
36

Kd without
CsMPs (L/g)

Kd with CsMPs
(L/g)

1400
1910
1100
4600
3200
850

1700
1950
1700
14 0009300
1300

The characteristics of 5 CsMPs deposited on a non-fabric cloth 50 km west of the FDNPP
were investigated by Kurihara et al [49]. Diameters varied from 1.6-2.7 µm, the total
137
Cs-activity ranged from 0.7–1.9 Bq, and 134Cs/137Cs-ratios between 0.96 and 1.17 were
found. Based on these properties, and the on ratios of 235U/238U, all these CsMPs were classified
as Type A originating from Unit 2.
The investigations of CsMPs in soil and suspended sediment samples [48, 53] indicate that only
a minor fraction of the 137Cs in the environment is associated with CsMPs. However, the longterm fate of CsMPs in the environment is not yet fully clarified. The low solubility in the
freshwater system indicates low bioavailability [51].

386.3. INTERNATIONAL EXPERIENCE ON PARTICLES WITH ENHANCEDRADIONUCLIDE CONCENTRATIONS
The occurrence of particles in the environment with enhanced levels of radionuclides was alsoa phenomenon that was detected after the Chernobyl accident [54]. However, due to thedifferent reactor type and the different specifications of the accident at Chornobyl, thecharacteristics of the particles are quite different compared to those found in the Fukushima
Prefecture. Due to the high activity of some particles released from the Chornobyl reactor, they
were called ‘hot particles’. These particles from the Chornobyl reactor are classified into
condensation particles and fuel particles.
6.3.1.

Condensation particles

Condensation particles were generated at high temperatures during the breakdown of fuelelements and typically have a size on the order of 1µm. Volatile fission products (isotopes of I,
Cs, etc.) were released into the atmosphere and condensed on inert particle carriers. Particles
of such kind were also detected after the test of nuclear weapons in the atmosphere. Some
condensation particles had relative high activities containing one dominating radionuclide ase.g. 106Ru and 140Ba (half-lives 374 d and 12.8 d) with activities in the range of 500–
10 000 Bq/particle. Due to the relatively short half-lives of these isotopes, there is no long-term
impact of such particles [54].
6.3.2.

Fuel particles

Fuel particles are small fragments of nuclear fuel, generated during the breakdown of fuelelements. Fuel particles had higher activity concentrations than condensation particles. They
were composed of uranium oxides, the radionuclide composition was like the fuel compositionin the damaged unit, but volatile nuclides (131I, 134Cs/137Cs, 106Ru, etc.) were depleted. The sizeof fuel particles ranged from a fraction of a micrometres to hundreds of micrometres; theiractivity was typically 100–1000 Bq/particle.
6.3.3.

Environmental behaviour

Within the 30-km exclusion zone around the damaged Chornobyl reactor, up to 105 fuelparticles per m² were found. Deposition of fuel particles decreased with distance from thereactor site. Fuel particles have a low solubility in water. Therefore, with increasing distancefrom the reactor, the fraction of water soluble and exchangeable forms increased since thecontribution of more soluble particles increased with distance. Due to the presence of waterinsoluble fuel particles, the fraction of non-exchangeable 137Cs in the fallout near Chornobyl
about 75%, whereas it was 40–60% in the Bryansk region at a distance of 200 km from thereactor, and only 10% in Cumbria (UK) at a distance of 2000 km [54].
Near the Chornobyl reactor, in the first years after the accident, leaching of radionuclides fromfuel particles was an important process; this caused an increased migration of radionuclides, inparticular for 90Sr. In soils, fuel particles had virtually disintegrated within 10 years. Due to thelow solubility of hot particles, radiocaesium released during the Chernobyl accident had higher
distribution coefficienst (Kd) than e.g. of radiocaesium originating from atmospheric nuclear
weapons tests. Consequently, migration in soil was slower, and the bioavailability radiocaesium
was lower in the area close to the NPP [54].
Far away from Chornobyl, the situation was different. In the first year after deposition, theuptake of 137Cs by plants was 4–5 times higher than that in areas with considerable fuel particle
39

deposition. In subsequent years, in particular the transfer of radiocaesium from soil to plants
declined due to the increasing sorption of caesium to clay minerals.
6.3.4.

Fukushima CsMPs and Chernobyl hot particles

Following both accidents in Fukushima and in Chornobyl, particles with enhanced levels ofradionuclides were found. However, the particles are quite different:

⎯
⎯
⎯
⎯
⎯

Fukushima type A particles have a similar size spectrum as condensation particles thatwere found e.g. after weapons’ fallout. However, type B particles are smaller than
Chernobyl hot particles;
Chernobyl-hot-particles are mainly fuel fragments, whereas CsMPs are of glassy nature
generated during any liquifying and evaporation processes of reactor materials [48];The total activity of the CsMPs is in general lower than of Chernobyl hot particles;
The hot particles released from the Chernobyl reactor contain a wider spectrum ofradionuclides, whereas the Fukushima-CsMPs contain mainly 137Cs;
Due to their larger diameter, Chernobyl hot particles deposited close to the reactor site,
the number of hot particles decreases with the distance from the reactor.

Due to their size, solubility, activity and chemical composition, particles with enhanced levelsof radionuclides raise several questions regarding dosimetry. These questions are currently
being investigated for the CsMPs.
A key parameter for dosimetric calculations is the gut absorption (transfer of radionuclides fromthe gut to the blood). For the calculation of dose conversion coefficient for intake of 137Cs withfood or water [55], a gut absorption of 100% is assumed, which is a conservative assumption.
The solubility of the CsMPs is relatively low, which may cause a lower gut absorption andlower values for the dose per unit intake [Sv/Bq]. Further studies are needed to confirm thishypothesis.

40

7.

SUCCESS OF DECONTAMINATION WORK

7.1. DECONTAMINATION ACTIVITIES IN THE FUKUSHIMA PREFECTURE
For planning of decontamination, the areas affected by the enhanced deposition of radionuclides
were classified in August 2011 [56] into the Special Decontamination Area (SDA) and theIntensive Contamination Survey Area (ICSA):⎯⎯The SDA consists of the former ‘Warning Zone within a 20 km radius of the Fukushima
Daiichi NPP, and the former ‘Planned Evacuation Zone’, which was situated beyond the
20 km radius from the NPP and where the additional annual dose for individuals could
exceed 20 mSv in the first year after the accident [14].
The ICSA includes those municipalities where the additional radiation dose in the firstyear was estimated to be between 1 and 20 mSv for individuals in some parts of themunicipality. Areas with an ambient dose rate of 0.23 µSv/h and above were assigned to
the ICSA. This value was used as criterion for designation of the ICSA, but it was not adecontamination target.

By March 2018, the decontamination activities in the Fukushima Prefecture except for the
Difficult-to-Return Zones (DRZ) were terminated. In the SDA, decontamination was performed
on 23 000 houses of residential areas, on 8700 ha of farmland, on 7800 ha of forests close toresidential areas and on 1500 ha of roads. In the ISCA, decontamination works were carried out
at 418 583 houses including the gardens, 11 958 public buildings, on 31 061 ha of farmland,4478 ha of forest near residential areas, and on 18 841 km of roads [57].
During the decontamination, approximately 14 million m³ [58] of soil and waste was generated
that is stored in Temporary Storage Sites (TSS). The transport of the soil and waste from the
TSS to an Interim Storage Facility started in 2015, and the transport was completed in 2022,
except for the DRZ.
The effectiveness of the decontamination work is compiled in Ref. [59]. The results are
summarized in Table 9 for agricultural land, forest, roads, and residential areas [59–61]. The
data are based on demonstration tests carried out by JAEA [59]. The effectiveness is quantified
as a reduction factor, which is determined as ratio of the gamma dose rates at 1-meter height
before and after the decontamination work. Interestingly, the effectiveness was higher in areas
with higher ambient dose rates.
The effectiveness of decontamination work under field conditions is shown in Figure 17 for theSpecial Decontamination Area [57]. Depending on the land-use, the average gamma dose rate
immediately after the decontamination work was reduced by 44–60%. Six to twelve months
after the decontamination work, the gamma dose rate was 55–76% lower than before thedecontamination; this decrease is due to ongoing attenuation processes, such as migration in
soil, street cleaning, and radioactive decay (of the relatively short-lived 134Cs). The results
achieved under field conditions are consistent with those obtained for a dose-rate of 1µSv/h inthe demonstration tests, as shown in Table 9.

41

Table 9: Reduction of gamma dose rate in percent resulting from decontamination work for the
Intensive Contamination Survey Area (ICSA) [59–61]
Decontamination measure
FarmlandInterchange topsoil and subsoil, add zeolite and potassium
Ploughing with zeolite and potassium
ForestRemove fallen leaves
Roads
Cleaning roads and ditches
Residential areas
Full remediation
Localised remediation

Reduction factor of gamma dose rate due todecontamination measures
Dose rate before remediation≤1 µSv/h
1–3 µSv/h
3–10 µSv/h>10 µSv/h
1.5
1.3

2.0
1.4

1.9
1.4

5.0
2.0

1.1

1.2

1.3

1.4

1.1

1.2

1.3

1.5

1.4
1.2

1.5
1.2

2.0
1.3

3.3
1.5

FIG. 17: Effect of decontamination work for different land-uses in the Special Decontamination Area.
Image credit: Fukushima Prefecture (redrawn from data in Ref. [57]).

FIG. 18: Distribution of gamma-dose rates in the Special Decontamination Area before and after
decontamination work. Image credit: Fukushima Prefecture [62].
42The distribution of the gamma dose rates before and after the decontamination work for the
SDA is shown Figure 18 above [62]. The measurements were performed before, immediately
after, and a few months after termination of the decontamination activities. The average valueof the gamma dose rate declined from 1.27 µSv/h to 0.63 µSv/h and 0.44 µSv/h, respectively.
These findings are in accordance with the results in Table 9 and Figure 17. The ongoing declineof the gamma-dose rate after the termination of the decontamination work confirms thepersistence of the measures; the results indicate that re-contamination is, if there is any, aphenomenon of minor importance.
7.2. INTERNATIONAL EXPERIENCE IN DECONTAMINATION AND
REMEDIATION IN TERRESTRIAL ENVIRONMENTS
The effectiveness of decontamination measures is the result of a complex interaction of aspectrum of factors e.g. the radionuclide, the surface, the depth profile of radionuclide
concentration in soil, and the land-use. Much experience in decontamination and remediationof contaminated land has been gained in the decades after the Chernobyl accident [37]. Studies
have been carried out under controlled experimental conditions as well as in the field.
Remediation work focused on both the reduction of external and internal exposure.
Table 10 summarizes the achievable decontamination factors for contaminated surfaces for avariety of measures [63] tested in an area affected by the Chernobyl fallout. The highest
reduction of the dose rate can be achieved if the radioactivity is removed from the surfaces (e.g.
removal of soil, sandblasting of surfaces, lining of asphalt). The large variation is due to thevarying thickness of the removed surface layers; in general, the reduction factor increases withthe thickness of the removed layer. However, it should be noted that the results represent very
well controlled experimental conditions [63], which are extremely difficult to achieve if appliedin a normal living environment. For field conditions, decontamination factors from the lower
part of the range are considered more realistic. Nevertheless, the data indicate that carefully
implemented measures under favourable conditions may be quite effective. The
decontamination factors elaborated during demonstration tests in Japan (Table 9) under more
realistic conditions are smaller; they are consistent with the lower values of the range presented
in Table 10. Similar techniques were also applied during the decontamination work in areas
affected by the Chornobyl fallout. However, due to the high costs, not all affected areas weresystematically treated after the Chernobyl accident [37].
The reduction of the annual effective dose from external exposure due to decontamination work
was studied where gamma dose rate measurements and individual external dose measurements
before and after large-scale decontamination campaigns in the Bryansk oblast (RussianFederation) in 1989 were carried out [64]. For the average population, annual effective doses
from external exposure were reduced by 10–20%. The effect for outdoor workers was less than
10%, whereas the reduction for children in schools and kindergartens was approximately 30%.
In Belarus, Russia, and Ukraine, after the Chernobyl accident, the intake of food was in many
areas the dominating contributor to the annual exposure of people. Therefore, much attention
was given to the uptake of 137Cs from soil, as this process represents a potential long-termsource for internal exposure of people. A strong emphasis was given to exploring theeffectiveness of countermeasures to reduce the 137Cs-uptake by agricultural crops.
The situation in the Fukushima Prefecture was different. Due to the intensive food monitoring
and the low activity limits for radiocaesium in food, doses from the intake of radiocaesium infood remained low. It should also be noted that the uptake of 137Cs from soils in the Fukushima
Prefecture is relatively low due to the strong sorption of radiocaesium to clay minerals.
43

Table 11 compares the effectiveness of a spectrum of countermeasures for reducing the uptakeof radiocaesium from soil9 applied after the accidents at Chornobyl and the Fukushima Daiichi
NPPs [14]. Most effective, but also most expensive, is the removal of the soil. A similareffectiveness can be achieved with deep ploughing, where the activity is buried to a depth where
the radionuclides are no longer available for root uptake. However, deep ploughing represents
a severe impact for the soil quality, and it cannot be applied at all sites. The othercountermeasures are part of the normal agricultural practice. The reduction factors depend on
the prevailing conditions, such as the site-specific agricultural practice and the soil and plant
type; these factors differ between the areas affected. Nevertheless, the range of reduction factors
obtained after both accidents is similar for the various remediation measures.

Table 10: Achievable decontamination factors (dimensionless) for various urban surfaces [63]Surface
Windows
Walls
Roofs
Gardens
Gardens
Trees and shrubs
Streets
Asphalt

Decontamination technique
Washing
Sandblasting
Hosing and /or sandblasting
Digging
Removal of Surface
Cutting back or removal
Sweeping and vacuum cleaning
LiningDecontamination factor
10
10–100
1–100
6
4–10
≈10
1–50
>100

Table 11: Comparison of reduction factors for radiocaesium transfer to agricultural products
derived after the accidents at Chornobyl and Fukushima Daiichi (Annex IV of Ref. [14])Remediation option
Topsoil removal
Normal ploughing
Deep ploughing a, b
Reverse tilling of soil
Application of potassium
Application of organic fertilizers
Application of sorbents
Radical renovation
Simple renovationab

Reduction factor for the uptake of radiocaesium from soil
Chernobyl
Fukushima
Not applied
4–5
2.5–3
1.5–2.5
3–8
2–3
10–16
Not applied
1.5–3
1.5–3
1.5–2
1.3–2.5
1.3֪2
1.5–1-8
2–9
8
2–3
4

Deep ploughing to replace topsoil up to a depth of 5 cm with soils taken from a depth of 50 cm.
Reduction of the external dose rate at the height of 1 m.

9

Decontamination is quantified in terms of reduction of the uptake of 137Cs from soil. In Table 10, the effectivenessis quantified in terms of the reduction of the gamma dose-rate over the treated area.

44

8.

INTERACTION WITH THE PUBLIC

8.1. ACTIVITIES IMPLEMENTED AFTER FUKUSHIMA ACCIDENT
The release of man-made radionuclides to the environment attracts much attention among the
population in the affected areas. Fears, anxieties, concerns on the future development,
scepticism about the radiological impacts and on the management of environmental
contaminations are typical phenomena observed in the aftermath of accidental releases ofradionuclides [14].
Following the accident in the FDNPP mechanisms were established to provide information to
the public on the radiological status in the Fukushima Prefecture, on the planning and on the
progress of decontamination activities. A wide range of topics were addressed to disseminate
information and guidance on radiation safety [57], including implications for agriculture,
fishing, food supply, environmental monitoring, lifting of restrictions, and the future
development of the radiological situation.
For this purpose, the municipalities and the Fukushima Prefecture made use of different
information channels as:

⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯

The Commutan Fukushima (Fukushima Prefectural Centre for Environmental Creation)
was established in 2016. Since then, this Centre been also one of the important
information channels for the public.
Local newspapers, radio stations and TV programmes
Organisation of explanatory and consultation meetings for the people living in affected
areas
Providing basic and comprehensive information that helps people understanding
radiological topics and the state of the region after decontamination
Distributing pamphlets, comic books, and videos addressing radiation-related topics
The Environmental Regeneration Plaza, set up by the Ministry of the Environment, is an
information centre in Fukushima City with interactive exhibitions and workshops onradiation-related topics
Visit of experts in municipalities, communities, and schools for discussing actual topics
related to the radiological situation and future developments
Establishing a website to share information on efforts toward restoration and reconstruction,
including decommissioning, decontamination, and improvement of living environment, as wellas activities to revitalize and revitalize the economy of the Fukushima Prefecture10.

Over time, the focus of the information campaign shifted from the simple transmission of resultsfrom measurements and of scientific knowledge to a dialogue with the population on radiationrelated issues. The intention of the dialogue with the people is to let people develop forthemselves a sense for the safety of their municipalities.
Although after the termination of the decontamination work, the gamma dose rate declined
steadily, concerns remained regarding radiation risk, storage of removed soils and wastes, andthe possible implications for the daily life. In principle, there is a rational understanding of the

10 Available from: https://www.pref.fukushima.lg.jp/site/portal-english/45

radiological circumstances; nevertheless, the perception of the situation is often characterized
by anxieties and fears.
Efforts are still being undertaken to offer correct and easily understandable information forsupporting the communication between the local governments and citizens. The aim is toincrease the awareness of the enormous remediation efforts for remediation and the resulting
improvement in environmental conditions among both, local and country-wide population.
8.2. INTERNATIONAL EXPERIENCE
The experience gained after nuclear and radiological accidents has shown that the interaction
with the population in the affected areas is essential. This includes activities such as timely
information of the public on the environmental contaminations, a dialogue on the radiologicalhazards arising from environmental contaminations, discussion about measures to mitigate
radiological, social, and economic consequences, and fora to address any concerns raised by
the public and specific groups.
The radiological incidence on Goiânia (Brazil) happened in 1987. A medical 137Cs source withan activity of about 52 TBq was opened by scrap collectors. A large part of the 137Cs dispersedin the environment and caused exposures to the local population. Comprehensive activities formonitoring people and the environment, for decontamination of the affected area, and for the
management of the decontamination waste were initiated. Details including the experience
made with the interaction with the public are summarized in Ref. [65].
Valuable insights were also achieved during the ICRIN programme (International Chernobyl
Research and Information Network) [66]. This programme was launched in 2009 by fourInternational Organisations (UNDP, UNICEF, IAEA, WHO)11 in rural areas affected by the
Chernobyl fallout of Belarus, Russia, and Ukraine. The aim of the program was to provide
scientific correct information on radiation-related topics, to initiate a dialogue with the local
population on agricultural practice, and to discuss individual habits that could reduce exposures.
Additionally, initiatives started to foster the economic development of these areas.
During the cooperation of the Fukushima Prefecture with the IAEA, the global experience frominteraction with the public in post-accidental situations were discussed in detail. The essential
points of the discussion are summarized in Table 12.
The discussions underlined that the interaction with the public is a complex process. A special
challenge is that — besides the official information sources — rumours will be around, andother information sources will become available as the contamination situation develops.
Experience shows that not all information sources are reliable. So, conflicting information willbe spread. It may be difficult for the people to clearly differentiate between reliable and nonreliable information sources, which undermines confidence in the official information channels.
Therefore, according to the experience made after the Chernobyl and the Goiânia accidents, thedevelopment, and maintenance of trust is the most important factor for the successful dialogue
and fruitful discussions with the local and nation-wide population.

11

UNDP: United Nations Development Programme; UNICEF: United Nations International Children’s
Emergency Fund; IAEA: International Atomic Energy Agency; WHO: World Health Organization.

46

Table 12: Aspects on communication with the public identified as essential during managementof post-accidental situations outside Japan [65, 66]
Item

Information

Essential features

⎯
⎯
⎯
⎯
⎯

Distribution of
information

⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯

Direct contact topeople⎯⎯⎯⎯Transparency: Where does the information come from?
Credibility: Is the source of information trustworthy?
Completeness: What is known, what is uncertain? Are the knowledge gaps relevant?
Status of the radiological situation: What has happened, what is the current situation, what
will be next?
Tailored information: Addressing concerns of specific groups as e.g. children, farmers,
leisure facilities
Radio and TV
Internet and social media
Print media including brochures
Establishment of information centers
Involvement of respected and credible persons in the dissemination of scientifically correct
information
Involve physicians and teachers in the dissemination of results
Organisation of information events to allow dialogues and discussions with affected
peopleAvailability of competent experts in the public, e.g. on marketplaces, cultural events, local
festivals
Establishment contact points and information services for allowing immediate
information, as necessary
Availability of competent and trustworthy contact persons
Monitoring for privately produced foodFace-to-face discussions on radiation issues and the resulting implications, providing
advice to individuals on social and economic topics

47

9.

SUMMARY

The report summarizes the results of the cooperation of the Fukushima Prefecture and theInternational Atomic Energy Agency in the field of decontamination and remediation of areas
affected by the deposition of radionuclides during the accident in the Fukushima Daiichi
Nuclear Power Station. The main findings of the discussions and findings of the work carriedout from 2018 to 2022 are:⎯Comprehensive monitoring and research programs were initiated in 2011 for studying thefate of radionuclides in freshwater systems of the Fukushima Prefecture. As expected,
immediately after the deposition, the maximum level of 137Cs in river water is observed.
The concentrations of dissolved and particulate 137Cs in river water declined steadily since
2011.

⎯

The concentrations of suspended sediments in river water increase with rising waterlevels. Caesium-137 activity concentrations in suspended sediments tend to be higher
during periods of low flow rates.

⎯

In forested areas, forest soils and litter may significantly contribute to the concentrationsof suspended sediments in rivers.

⎯

The concentrations of dissolved and particulate 137Cs in rivers of the Fukushima
Prefecture were modelled by application of the TODAM model. For the cases
investigated in detail, measurements and predictions agree reasonably well.

⎯

Usually, the time-dependence of 137Cs in river water can be described by exponentialfunctions with one to three components representing different phases after the deposition:• Immediately after deposition, a decline of 137Cs in European rivers according to a halflife of 5 days during a period of about 2–3 weeks was observed. However, many data
sets do not include the initial phase with the fast decline.
• Most data sets cover an observation period of 5–15 years starting several months afterradionuclide deposition. For rivers of in the Fukushima Prefecture, the values for thehalf-life of 137Cs for 48 data sets of river water range from 0.7–16 years. Only 3 values
were below 1 year, and only three values were above 5 years. Forty-two values werein the range from 1.1–4.6 years.
• If the observation period is long enough, in some cases a third phase can be identified.
However, quantifying a third decline component requires observation times of at least
15 years. Such long observation periods cannot yet be available for Fukushima
Prefecture.
• In water of 25 rivers in Europe and West Asia, a long-term component with aneffective half-life of 16 years was identified. The contribution to the overall decline ofthis component was only 0.5% and the relevance in practice is of minor importance.
• In general, the time trends observed in the Fukushima Prefecture and in other parts of
the world agree reasonably well. The general pattern of the decline is quite similar for
both.

⎯

48

The loss of 137Cs due to run-off depends on the land-use. The loss of 137Cs increases withincreasing fractions of rice paddies, farmland, and residential areas.

⎯

Decontamination activities in catchment areas cause a higher loss of 137Cs with surface
run-off. In a study carried out during ongoing decontamination work, a total loss of 137Cs
due to surface run-off of the order of 0.03% per month was found. The 137Cs -reduction
rate due to radioactive decay is 0.19% per month.

⎯

Leaching of 137Cs from forest and grassland litter can cause an increase of dissolved 137Cs
levels in the surface runoff water following rainfall.

⎯

Remediation work was carried out in a part of a river channel of the Fukushima
Prefecture, where a reduction in the gamma dose rate by approximately a factor of 2 wasobserved. This effect persisted also during the next years.

⎯

International experience shows that decontamination works in rivers are challenging due
to the dynamic nature of flowing waters. Engineering measures are costly and often
difficult to implement, and the overall impact on public doses remains low. For reducing
exposures to the populations, restrictions on the abstraction of drinking water and fishingwere most effective.

⎯

Following both accidents in Fukushima Daiichi and at Chernobyl, particles with enhanced
levels of radionuclides were detected. The Chernobyl hot particles are fuel fragments, andthey are different from the Caesium-Micro-Particles (CsMPs) which are found in the
Fukushima fallout. CsMPs are smaller and contain much lower activities than thosereleased from the Chornobyl reactor.

⎯

The decontamination work in the Fukushima Prefecture was terminated in 2018 except
for the Difficult-to-Return-Zone. In the Special Decontamination Area (SDA), theaverage gamma dose rate immediately after the decontamination work was reduced by
44–60%. Six to twelve months after the decontamination work, the gamma dose rate was
55–76% lower than before the decontamination. These reductions are consistent with theexperience made after the Chornobyl accident.

⎯

For reducing 137Cs -levels is crops, a similar spectrum of techniques was applied as after
the Chernobyl accident. The effectiveness of the countermeasures was — as far as being
comparable — generally the same as that achieved after the Chernobyl accident.

⎯Interaction with the public during the management of post-accident situations is acomplex process. The interests and concerns of numerous groups and individuals need tobe addressed, which underlines the need for a tailored, situation-specific communication
strategy to initiate and maintain a dialogue with the population in the affected areas.

⎯

A matrix is suggested to define a structure for data reporting to enable a comprehensive
and concise compilation of the results elaborated in the Fukushima Prefecture on the
behaviour of radiocaesium in the environment and on decontamination of contaminatedareas.

49

APPENDIX I.

DYNAMICS OF CAESIUM-137 IN JAPANESE AND
EUROPEAN RIVERS

Table I.1: Compilation of data to describe the dynamic of 137Cs in rivers, half-lives are given
for the short-term, the intermediate and the long-term component of the decline. If more than
one component is given, the weighting factors for these components are given in brackets.
River or site name

Observation
periodMediumEuropean rivers affected by the Chernobyl accident
Pripyat (Ukraine)
Dissolved
May 1986,
Dnieper (Ukraine)
Dissolved
Week 1–3 after
Glatt (Switzerland)
Dissolved
deposition
Elbe (Germany)
Dissolved
20 May–July
Po (Italy)
Dissolved
1986
European rivers
1–15 May 1986
9 Ukrainian rivers
1987–1991
Dissolved
5 Finnish rivers
1987–1991
Dissolved
5 Belarussian rivers
1987–1991
Dissolved
Dora Baltea (Italy)
1987–1991
Dissolved
Rhine (Germany)
1987–1991
Dissolved
Rhine (Germany)
1987–1991
Particulate
Pripyat (Ukraine)
1987–1991
Dissolved
Pripyat (Ukraine)
1995–1998
Dissolved
Dnieper (Ukraine)
1995–1998
Dissolved
Desna (Ukraine)
1995–1998
Dissolved
5 Finnish rivers
1995–2002
Dissolved
5 Belarussian rivers
1994–1998
Dissolved
Pripyat (Ukraine)
1995–1998
Particulate
Dnieper (Ukraine)
1995–1998
Particulate
Desna (Ukraine)
1995–1998
Particulate
Pripyat (Ukraine)
1987–2001
Unfiltered water
Pripyat (Chernobyl)
1987–2001
Unfiltered water
Dnieper (Ukraine)
1987–2001
Unfiltered water
Uzh (Ukraine)
1987–2001
Unfiltered water
Teterev (Ukraine)
1987–2001
Unfiltered water
Irpen (Ukraine)
1987–2001
Unfiltered water
Braginka (Ukraine)
1987–2001
Unfiltered water
Ilya (Ukraine)
1987–2001
Unfiltered water
Sakhan (Ukraine)
1987–2001
Unfiltered water
Glinitsa (Ukraine)
1987–2001
Unfiltered water
Pripyat (Ukraine)
1988–2018
Particulate
Dnieper (Ukraine)
1989–2012
Particulate
25 rivers in Asia and
1987–2001
Unfiltered water
EuropeIput river (Russia)
1987–1991
Kymijoki (Finland)
1990–1996
Kokemäenjoki
1990–1996(Finland)Effective half-lives(Weighting factors, if available)
Teff,1
Teff,2
Teff,3(short-term) (intermediate) (long-term)

Reference
number

11 d
9.0 d
19 d
18 d

[67]

35 d

[68]

5d
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
20 d
(0.905)––

1.0-2.1 y
1.7-4.3 y
1.0-1.4 y
1.9 y
1.3 y
1.9 y
1.6 y
3.8 y
3.6 y
9.9 y
5.2-7.5 y
2.1-4.5 y
8.2 y
7.5 y
2.6 y
3.0 y (*)
2.5 y (*)
1.9 y (*)
2.6 y (*)
3.1 y
2.8 y
5.3 y (*)
3.2 y
2.7 y (*)
2.0 y (*)
1.1 y (*)
3.6 y (*)
1.6 y
(0.09)
1.3 y
6.0 y

–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
14 y (*)
15 y (*)
8.3 y (*)
6.2 y (*)––
6.0 y (*)–
16 y (*)
21 y (*)
10 y (*)
7.6 y (*)
16 y
(0.005)
–
–

[69]

–

3.5 y

–

[67]

[70]

[71]
[30]
[72]
[73]

51

Table I.1. (cont.)
River or site name

Observation
periodMediumJapanese rivers affected by the FDNPP accident
Ukedo
2015–2018
Dissolved
Particulate
Ota
2015–2018
Dissolved
Particulate
Koutaishi
2011–2013
Dissolved
Iboishi
2011–2013
Dissolved
Ishidaira
2011–2013
Dissolved
Fukushima rivers**
2012–2014
Dissolved
Odaka river
2012–2016
Sediment
River waterOta
2012-2016
Sediment
River waterNiida
2012-2016
Sediment
River waterMano
2012-2016
Sediment
River water
Mizusakai

2011–2016

Particulate

Kuchibuto_Upper

2011–2016

Particulate

Kuchibuto_Middle

2011–2016

Particulate

Kuchibuto_Down

2011–2016

Particulate

Fushiguro

2011–2016

Particulate

Iwanuma

2011–2016

Particulate

ManoOjimadazeki
Matsubara
Onahama
Tsukidate
Nihonmatsu
MiyotaNishikawa
Kitamachi
Kawamata
Marumori
SenoueYagitaKuroiwa
Tomita
Ota
Odaka
Asami
Tsushima
Ukedo
TakaseHaramachi
Akanuma

2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016
2012–2016

Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate
Particulate

52

Effective half-lives(Weighting factors, if available)
Teff,1
Teff,2
Teff,3(short-term) (intermediate) (long-term)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
1.6 y
(0.64)
135 d(0.79)
120 d(0.74)
274 d(0.64)
66 d(0.92)
80 d(0.92)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–

3.7 y
2.3 y
2.4 y
1.6 y
0.69 y0.69 y1.5 y1.8±0.5 y
4.7±1.3 y
3.7±0.6 y
1.5±0.4 y
2.1±0.6 y
1.8±0.6 y
1.0±0.2 y
2.1±0.2 y
0.9±0.1 y
2.7 y(0.36)
2.0 y(0.21)
1.6 y(0.26)
1.4 y(0.36)
1.8 y
(0.08
1.5 y
(0.08)
8.2 y
4.6 y
3.7 y
2.1 y
1.1 y
1.6 y
2.9 y
2.9 y
1.5 y
1.1 y
1.8 y
2.4 y
16 y
1.3 y
1.5 y
3.8 y
11 y
2.1 y
1.7 y
2.8 y
1.7 y
3.0 y
2.0 y

–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–

Reference
number

[19]

[74]
[75]

[76]

–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–

[15]

[15]

Table I.1. (cont.)
River or site name

Observation
periodMediumAbukuma River

2011–2017

Particulate

2011–2017

Particulate

2011–2017

Dissolved

Hiso River

2011–2021

Particulate

Hiso River

2011–2021

Dissolved

Wariki River

2011–2021

Particulate

Wariki River

2011–2021

Dissolved

Rivers coastal regionof FP
Abukuma & riversof coastal region

Effective half-lives(Weighting factors, if available)
Teff,1
Teff,2
Teff,3(short-term) (intermediate) (long-term)
0.14 y1.5 y–(0.96)(0.04)
0.12 y2.6 y–(0.93)(0.07)
0.14 y2.6 y–(0.94)(0.06)
0.068 y1.7 y–(0.97)(0.03)
0.20 y1.8 y–(0.914)(0.086)
0.071 y1. 9y–(0.975)(0.025)0.24 y1.7 y–(0.82)
0.18)

Reference

[77]

[21]

* The data indicate that the decrease of 137Cs in these rivers follows an exponential function with two components.
However, the weighting factors for the 2 components are not given by the authors, since the uncertainty of thelong-term component is very high, and it was not considered reasonable to assign a specific value for the weighting
factors. The values should therefore be considered as a first estimation of the long-term component. The highuncertainty of the long-term component is due to the short observation period compared to its ecological half-life.
** The effective half-lives were derived from measurements in the Uta, Mano, Niida, Ohta, Odaka, Ukedo, andAbukuma Rivers.

53

APPENDIX II. TIME-DEPENDENCE OF CAESIUM-137 IN SUSPENDED
SEDIMENTS OF RIVERS OF THE FUKUSHIMA PREFECTURE
Table II.1: Underlying data for Figure 4a of the main text for the dynamics of 137Cs insuspended sediments of rivers within the 80 km-zone around the Fukushima Daiichi Nuclear
Power Plant form 2011–2021 [15, 78].
Sampling
date
2011-06-27
2011-07-12
2011-07-20
2011-07-25
2011-08-01
2011-08-09
2011-08-16
2011-08-24
2011-08-30
2011-09-10
2011-09-17
2011-12-08
2011-12-22
2012-01-14
2012-01-28
2012-02-11
2012-02-21
2012-02-25
2012-03-09
2012-03-20
2012-03-29
2012-04-17
2012-04-25
2012-05-15
2012-05-30
2012-06-21
2012-06-29
2012-12-05
2012-12-19
2013-01-11
2013-01-23
2013-02-27
2013-04-18
2013-05-21
2013-06-18
2013-07-26
2013-08-09
2013-08-23
2013-09-12
2013-09-26
2013-10-30
2013-11-21
2013-12-24
2014-01-17
2014-02-26
2014-08-05

Site(river name)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)

Activity in suspended
sediments (Bq/kg)
4.85E+04
3.85E+04
9.28E+03
2.42E+04
5.54E+04
2.57E+03
3.39E+04
3.42E+04
1.15E+04
2.75E+04
3.50E+04
1.31E+03
1.21E+04
2.65E+04
2.46E+04
2.53E+04
2.55E+04
2.54E+04
2.00E+04
1.52E+04
1.32E+03
1.73E+03
1.63E+04
7.99E+03
1.73E+04
1.15E+04
1.63E+04
6.29E+03
8.45E+03
1.45E+04
9.49E+03
1.07E+02
8.65E+03
4.53E+03
9.76E+03
1.42E+04
9.80E+03
1.43E+04
1.93E+04
9.62E+03
4.32E+03
1.30E+04
1.26E+04
9.49E+03
1.61E+04
4.83E+03

Standard
deviation
1.45E+03
1.25E+03
5.57E+02
1.06E+02
1.11E+03
6.19E+02
1.34E+03
6.45E+02
2.80E+02
1.04E+03
2.10E+03
3.37E+02
4.63E+02
4.17E+02
1.10E+03
7.02E+02
1.16E+03
2.29E+02
2.33E+02
5.94E+02
6.17E+02
1.48E+02
4.31E+02
1.87E+02
6.53E+02
4.00E+02
1.93E+02
2.41E+02
4.22E+02
2.92E+02
3.51E+02
2.19E+02
2.72E+02
2.28E+02
3.87E+02
3.11E+02
3.12E+02
2.56E+02
3.06E+02
1.75E+02
1.04E+02
3.16E+02
3.22E+02
1.82E+02
3.71E+02
9.10E+01

Catchment area
(km²)
7.5

Mean deposition in
the catchment (kBq/m²)
745.2

55

Table II.1. (cont.)
Sampling
date

Site(river name)2014-09-09
2014-10-21
2014-12-04
2015-01-15
2015-04-22
2015-05-29
2015-07-21
2015-09-03
2015-12-24
2016-01-21
2016-02-23
2016-04-15
2016-09-27
2016-12-21
2017-03-01
2017-05-08
2017-07-10
2017-09-05
2017-12-12
2018-05-14
2018-05-30
2018-07-03
2018-10-11
2018-12-03
2019-04-24
2019-07-05
2020-02-26
2020-05-15
2020-07-06
2020-10-21
2021-02-01
2011-06-27
2011-07-06
2011-07-12
2011-07-20
2011-07-25
2011-08-01
2011-08-09
2011-08-16
2011-08-24
2011-08-30
2011-09-10
2011-09-17
2011-12-08
2011-12-22
2012-01-14
2012-01-27
2012-02-11
2012-02-21
2012-02-25
2012-03-09
2012-03-20

Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Mizusakai (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)

56

Activity insuspended
sediments (Bq/kg)
3.30E+03
1.80E+03
5.37E+03
6.88E+03
3.95E+3
5.00E+3
3.33E+3
3.56E+3
2.33E+3
3.24E+3
3.08E+3
2.99E+3
2.24E+3
3.53E+3
1.96E+3
3.87E+3
4.08E+3
3.04E+3
2.46E+3
4.54E+3
3.15E+3
6.44E+3
4.19E+3
3.86E+3
2.88E+3
2.41E+3
7.73E+2
9.32E+2
5.10E+2
3.40E+2
1.58E+3
5.75E+04
3.32E+04
3.45E+03
3.58E+04
4.13E+04
3.41E+04
2.92E+04
3.68E+04
2.02E+04
2.90E+04
3.09E+03
3.28E+04
7.40E+03
9.63E+03
6.84E+03
1.07E+03
8.46E+03
2.32E+04
2.94E+04
1.44E+04
1.32E+04

Standard
deviation
9.60E+01
5.30E+01
1.18E+02
1.66E+02
4.70E+1
9.50E+1
4.10E+1
8.10E+1
4.60E+1
1.05E+2
6.60E+1
9.50E+1
7.50E+1
9.00E+1
1.03E+2
1.69E+2
9.40E+1
3.30E+1
2.80E+1
1.20E+2
3.60E+1
1.75E+2
5.40E+1
9.00E+1
1.52E+2
7.30E+1
2.90E+1
2.70E+1
2.70E+1
1.10E+1
6.10E+1
2.50E+01
1.10E+03
1.43E+03
1.68E+03
1.61E+03
1.37E+03
6.14E+02
1.36E+03
4.23E+02
1.72E+02
1.36E+03
1.12E+03
3.25E+02
5.24E+02
2.84E+02
7.10E+01
7.10E+01
6.48E+02
6.61E+02
4.21E+02
1.90E+02

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

21.4

477.4

Table II.1. (cont.)
Sampling
date

Site(river name)2012-03-29
2012-04-17
2012-04-25
2012-05-15
2012-05-30
2012-06-21
2012-06-29
2012-12-05
2012-12-19
2013-01-11
2013-01-23
2013-02-27
2013-04-18
2013-05-21
2013-06-18
2013-07-26
2013-08-08
2013-08-23
2013-09-12
2013-09-26
2013-10-30
2013-11-21
2013-12-24
2014-01-17
2014-02-26
2014-08-05
2014-09-09
2014-10-21
2014-12-04
2015-01-15
2015-04-22
2015-05-29
2015-07-21
2015-09-03
2015-10-22
2015-12-24
2016-01-21
2016-02-17
2016-04-15
2016-09-27
2016-12-21
2017-03-01
2017-05-08
2017-07-04
2017-09-05
2018-07-03
2018-10-11
2018-12-03
2019-04-24
2019-07-05
2019-11-19
2020-02-26

Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)

Activity insuspended
sediments (Bq/kg)
1.16E+04
1.75E+04
1.09E+04
1.06E+04
1.19E+04
6.65E+03
1.06E+04
8.47E+03
1.30E+04
9.94E+03
1.07E+04
1.05E+04
7.49E+03
8.53E+02
7.22E+03
1.02E+04
1.04E+04
8.12E+03
2.16E+03
9.52E+03
6.75E+03
1.22E+04
1.11E+04
1.17E+04
7.43E+03
3.31E+03
5.32E+03
1.95E+03
4.16E+02
7.14E+03
2.26E+3
3.43E+3
2.89E+3
3.79E+3
1.12E+3
1.53E+3
3.91E+2
7.08E+2
9.83E+2
7.27E+2
7.17E+2
6.49E+2
1.60E+3
1.71E+3
1.07E+3
1.34E+3
7.60E+2
1.90E+3
1.42E+3
9.97E+2
7.97E+2
9.13E+2Standard
deviation

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

3.94E+02
1.07E+02
1.53E+02
3.15E+02
4.58E+02
8.70E+01
1.43E+02
2.29E+02
2.80E+02
1.88E+02
3.26E+02
3.45E+02
2.72E+02
2.91E+02
9.70E+01
2.34E+02
4.00E+02
2.38E+02
4.70E+01
1.40E+02
7.00E+01
2.76E+02
3.14E+02
2.04E+02
1.46E+02
7.30E+01
1.43E+02
4.10E+01
1.15E+02
1.59E+02
3.70E+1
9.00E+1
4.30E+1
6.80E+1
2.40E+1
3.10E+1
1.80E+1
2.40E+1
3.10E+1
2.40E+1
2.50E+1
3.40E+1
4.70E+1
4.00E+1
1.60E+1
5.20E+1
1.60E+1
9.90E+1
4.80E+1
6.10E+1
1.70E+1
2.50E+1

57

Table II.1. (cont.)
Sampling
date

Site(river name)2020-05-15
2020-07-06
2020-10-21
2021-02-01
2011-06-27
2011-07-06
2011-07-12
2011-07-20
2011-07-25
2011-08-01
2011-08-10
2011-08-16
2011-08-24
2011-08-30
2011-09-10
2011-09-17
2011-12-08
2011-12-22
2012-01-14
2012-01-28
2012-02-11
2012-02-21
2012-02-25
2012-03-10
2012-03-20
2012-03-29
2012-04-17
2012-04-26
2012-05-15
2012-05-30
2012-06-22
2012-06-29
2012-12-05
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-21
2013-06-18
2013-07-26
2013-08-09
2013-08-23
2013-09-12
2013-09-26
2013-10-30
2013-11-20
2013-12-24
2014-01-16
2014-02-25
2014-08-07
2014-09-09

Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-upper (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)

58

Activity insuspended
sediments (Bq/kg)
7.09E+2
8.14E+2
4.65E+2
1.67E+3
3.27E+04
1.21E+04
1.37E+04
1.28E+04
1.51E+04
1.85E+04
9.29E+03
1.81E+04
1.75E+04
1.14E+04
6.76E+03
1.27E+04
7.73E+03
3.04E+03
4.33E+03
3.16E+03
5.65E+03
3.31E+03
1.20E+04
1.19E+04
6.65E+03
7.13E+03
8.27E+03
5.58E+03
6.58E+03
6.63E+03
3.66E+03
5.96E+03
6.82E+03
2.50E+03
5.69E+03
1.05E+04
1.28E+04
5.04E+03
3.26E+03
4.32E+03
3.85E+02
3.40E+03
1.34E+03
5.56E+03
3.28E+03
1.84E+03
4.16E+03
3.88E+03
7.33E+03
4.72E+03
2.10E+03
1.73E+03

Standard
deviation
2.00E+1
4.00E+1
1.30E+1
6.60E+1
1.99E+03
5.60E+02
6.64E+02
6.61E+02
5.88E+02
7.68E+02
2.68E+02
8.27E+02
7.64E+02
3.20E+02
2.50E+02
6.02E+02
4.65E+02
1.38E+02
2.51E+02
1.40E+02
1.91E+02
1.85E+02
7.94E+02
3.09E+02
2.43E+02
1.61E+02
2.43E+02
1.69E+02
1.74E+02
3.38E+02
5.20E+01
1.14E+02
2.45E+02
1.95E+02
1.42E+02
2.77E+02
4.38E+02
1.63E+02
1.72E+02
8.60E+01
7.70E+01
2.25E+02
4.50E+01
1.62E+02
8.40E+01
4.60E+01
6.40E+01
1.02E+02
9.60E+01
5.70E+01
5.40E+01
5.70E+01

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

62.8

357.2

Table II.1. (cont.)
Sampling
date

Site(river name)2014-10-21
2014-12-04
2015-01-15
2015-04-23
2015-05-29
2015-07-21
2015-09-03
2015-12-24
2016-01-21
2016-02-17
2016-04-15
2016-09-27
2016-12-21
2017-03-01
2017-05-08
2017-07-07
2017-09-05
2017-12-08
2018-05-11
2018-07-03
2018-10-11
2018-12-03
2019-04-24
2019-07-08
2019-07-17
2019-11-19
2020-01-21
2020-07-10
2020-10-21
2021-02-05
2011-06-27
2011-07-06
2011-07-12
2011-07-19
2011-07-25
2011-08-01
2011-08-10
2011-08-16
2011-08-24
2011-08-30
2011-09-10
2011-09-17
2011-12-08
2011-12-22
2012-01-14
2012-01-28
2012-02-11
2012-02-21
2012-02-25
2012-03-10
2012-03-20
2012-03-29

Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-middle (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)

Activity insuspended
sediments (Bq/kg)
1.06E+03
1.86E+02
2.99E+03
2.65E+3
1.94E+3
2.46E+3
2.35E+3
7.40E+2
1.19E+3
8.87E+2
7.15E+2
7.96E+2
1.19E+3
7.37E+2
7.60E+2
1.29E+3
1.08E+3
1.55E+3
6.68E+2
1.28E+3
1.37E+3
8.24E+2
3.74E+2
1.06E+3
9.74E+2
7.29E+2
2.31E+2
4.06E+2
2.43E+2
9.84E+2
4.56E+04
2.92E+04
2.41E+04
2.33E+04
1.98E+04
2.44E+04
1.82E+04
2.05E+04
1.30E+04
9.21E+03
1.73E+04
1.68E+04
3.94E+03
1.04E+04
1.17E+04
1.04E+04
1.85E+04
1.36E+04
2.55E+04
1.13E+04
1.21E+04
7.77E+03

Standard
deviation
4.10E+01
5.30E+01
7.30E+01
4.40E+1
3.80E+1
3.30E+1
4.20E+1
2.00E+1
4.50E+1
2.50E+1
2.50E+1
2.70E+1
3.50E+1
2.50E+1
3.50E+1
3.70E+1
2.50E+1
4.50E+1
1.60E+1
3.30E+1
3.60E+1
7.30E+1
4.20E+1
1.04E+2
3.60E+1
2.20E+1
8.00E+0
9.00E+0
9.00E+0
3.90E+1
1.98E+03
1.52E+03
6.38E+02
1.11E+03
5.48E+02
8.51E+02
9.60E+02
5.66E+02
6.98E+02
1.09E+02
6.48E+02
1.01E+03
1.65E+02
4.80E+01
6.34E+02
3.56E+02
1.18E+02
2.77E+02
3.26E+02
4.19E+02
2.10E+02
2.94E+02

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

135.2

269.1

59

Table II.1. (cont.)
Sampling
date

Site(river name)2012-04-17
2012-04-26
2012-05-15
2012-05-30
2012-06-22
2012-06-29
2012-12-05
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-21
2013-06-18
2013-07-26
2013-08-09
2013-08-23
2013-09-12
2013-09-26
2013-10-30
2013-11-20
2013-12-24
2014-01-16
2014-02-25
2014-08-05
2014-09-09
2014-12-04
2015-01-15
2015-04-23
2015-05-29
2015-07-21
2015-09-03
2015-12-24
2016-01-21
2016-02-17
2016-04-15
2016-10-24
2016-12-21
2017-03-01
2017-05-08
2017-07-07
2017-09-04
2017-12-08
2018-05-30
2018-07-03
2018-10-11
2018-12-03
2019-04-24
2019-07-26
2021-02-05
2011-07-11
2011-07-19

Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Kuchibuto-down (Kuchibuto)
Fushiguro (Abukuma)
Fushiguro (Abukuma)

60

Activity insuspended
sediments (Bq/kg)
9.54E+03
6.82E+03
8.67E+03
8.87E+03
8.21E+02
7.40E+03
7.98E+02
9.38E+03
4.29E+03
7.86E+03
7.09E+03
5.48E+03
5.86E+03
1.44E+04
8.36E+03
5.18E+02
2.30E+03
4.51E+03
3.92E+03
2.48E+03
3.89E+03
1.42E+02
4.52E+02
3.39E+03
1.86E+03
2.09E+03
1.70E+03
2.99E+03
3.00E+3
2.48E+3
2.79E+3
2.77E+3
1.23E+3
1.19E+3
1.76E+3
1.63E+3
1.98E+3
1.48E+3
9.16E+2
7.77E+2
1.87E+3
1.60E+3
1.83E+3
8.66E+2
1.63E+3
1.52E+3
8.00E+2
7.41E+2
1.45E+3
4.20E+2
5.53E+04
3.02E+04

Standard
deviation
2.72E+02
1.47E+02
2.79E+02
5.61E+02
1.72E+02
3.34E+02
3.10E+02
3.05E+02
1.32E+02
2.96E+02
1.43E+02
9.30E+01
2.99E+02
5.11E+02
2.35E+02
9.70E+01
8.80E+01
1.54E+02
1.21E+02
5.30E+01
1.06E+02
2.60E+01
1.03E+02
7.40E+01
5.10E+01
5.80E+01
6.40E+01
1.00E+02
6.50E+1
6.90E+1
5.00E+1
4.60E+1
1.03E+2
4.30E+1
6.10E+1
9.00E+1
5.50E+1
6.40E+1
3.20E+1
3.70E+1
5.50E+1
2.30E+1
5.20E+1
4.40E+1
5.30E+1
3.30E+1
1.05E+2
9.70E+1
5.90E+1
1.70E+1
1.80E+03
1.85E+03

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

3645

95.9

Table II.1. (cont.)
Sampling
date

Site(river name)2011-07-25
2011-08-09
2011-08-16
2011-08-24
2011-08-31
2011-09-10
2011-09-17
2011-12-09
2011-12-21
2012-01-13
2012-01-27
2012-02-10
2012-02-20
2012-02-26
2012-03-21
2012-03-30
2012-05-30
2012-06-28
2012-12-07
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-17
2013-05-20
2013-06-17
2013-09-12
2013-09-25
2013-11-19
2013-12-24
2014-01-16
2014-02-25
2014-08-04
2014-09-11
2014-10-20
2014-12-03
2015-01-13
2015-05-27
2015-07-15
2015-08-24
2015-10-08
2016-01-26
2016-02-16
2016-04-13
2016-10-24
2016-12-21
2017-03-01
2017-05-09
2017-07-07
2017-09-25
2017-11-10
2017-12-08

Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)

Activity insuspended
sediments (Bq/kg)
4.10E+04
3.23E+03
3.88E+04
3.25E+04
2.18E+03
3.09E+04
3.37E+04
5.16E+03
6.58E+03
1.34E+04
4.91E+03
3.77E+03
5.13E+03
1.01E+04
1.26E+04
1.61E+03
3.93E+03
1.53E+03
2.71E+03
2.62E+03
2.09E+03
2.54E+03
8.84E+03
4.51E+03
1.58E+03
4.99E+03
2.40E+03
1.75E+03
2.30E+03
2.49E+03
2.53E+02
2.82E+03
2.34E+03
2.55E+03
1.02E+02
2.17E+02
1.51E+03
2.35E+3
3.82E+3
2.05E+3
9.75E+2
1.32E+3
4.32E+2
7.61E+2
9.61E+2
4.34E+2
6.90E+2
4.27E+3
1.84E+3
2.76E+3
8.44E+2
9.09E+2Standard
deviation

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

9.71E+02
4.27E+02
9.80E+02
8.29E+02
4.18E+02
1.29E+03
1.24E+03
1.41E+02
2.64E+02
7.05E+02
1.84E+02
3.48E+02
3.98E+02
4.99E+02
4.49E+02
9.50E+01
2.32E+02
4.50E+01
1.36E+02
2.38E+02
4.90E+01
2.87E+02
1.72E+02
2.80E+01
1.25E+02
6.00E+01
6.00E+01
8.10E+01
8.40E+01
5.80E+01
5.70E+01
7.00E+01
8.00E+00
4.50E+01
8.60E+01
8.50E+1
1.29E+2
3.90E+1
2.00E+1
7.50E+1
3.40E+1
2.20E+1
3.20E+1
1.90E+1
3.90E+1
1.49E+2
3.10E+1
3.00E+1
1.90E+1
2.04E+2

61

Table II.1. (cont.)
Sampling
date

Site(river name)2018-05-30
2018-07-03
2018-10-17
2018-12-05
2019-04-09
2019-08-06
2020-09-04
2020-11-11
2021-02-05
2011-07-12
2011-07-19
2011-07-26
2011-08-10
2011-08-17
2011-08-25
2011-08-31
2011-09-10
2011-09-17
2011-12-09
2011-12-21
2012-01-13
2012-01-27
2012-02-10
2012-02-20
2012-02-27
2012-03-21
2012-03-30
2012-04-25
2012-05-15
2012-05-29
2012-06-28
2012-12-19
2013-01-09
2013-01-21
2013-02-27
2013-04-18
2013-05-20
2013-06-17
2013-07-26
2013-08-08
2013-08-23
2013-09-12
2013-09-25
2013-10-31
2013-11-19
2013-12-24
2014-01-16
2014-02-25
2014-08-04
2014-08-04
2014-09-11
2014-09-11

Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Fushiguro (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)

62

Activity insuspended
sediments (Bq/kg)
6.86E+2
5.81E+2
1.21E+3
1.06E+3
1.52E+3
1.12E+3
6.37E+2
7.67E+2
4.51E+2
3.09E+04
3.45E+03
2.83E+04
2.02E+04
4.44E+04
1.62E+04
2.01E+04
2.72E+04
2.81E+04
8.02E+03
6.44E+03
4.22E+02
7.45E+03
8.48E+03
8.34E+03
3.82E+03
1.46E+04
2.48E+04
4.57E+02
1.82E+03
3.08E+03
1.89E+03
3.18E+03
7.01E+03
2.91E+03
4.37E+03
4.54E+03
2.16E+03
2.05E+03
2.51E+03
6.69E+03
2.54E+03
2.95E+03
2.72E+03
2.23E+03
1.21E+03
1.14E+03
1.09E+03
1.31E+02
1.25E+03
2.35E+03
1.16E+03
2.29E+03

Standard
deviation
1.10E+1
9.70E+1
2.80E+1
3.30E+1
5.20E+1
4.00E+1
1.70E+1
2.10E+1
9.30E+1
1.61E+03
1.71E+03
1.01E+03
6.29E+02
2.00E+03
9.31E+02
6.86E+02
3.45E+02
1.64E+03
4.31E+02
1.99E+02
9.80E+01
2.23E+02
3.16E+02
3.54E+02
1.63E+02
7.21E+02
1.02E+03
2.25E+02
1.00E+02
5.30E+01
8.20E+01
1.71E+02
2.12E+02
1.08E+02
1.39E+02
3.30E+01
7.90E+01
8.50E+01
7.90E+01
1.03E+02
9.60E+01
8.70E+01
8.40E+01
5.50E+01
3.80E+01
3.80E+01
2.10E+01
3.40E+01
3.70E+01
6.00E+01
4.70E+01
6.40E+01

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

5313

88.4

Table II.1. (cont.)
Sampling
date

Site(river name)2014-10-20
2014-10-20
2014-12-03
2015-01-13
2015-01-13
2015-06-02
2015-08-03
2015-08-28
2015-10-14
2016-01-15
2016-04-11
2016-05-30
2016-08-02
2016-10-17
2017-01-06
2017-02-27
2017-05-11
2017-07-06
2017-12-04
2018-05-30
2018-07-03
2018-10-11
2018-12-05
2019-04-09
2019-08-05
2019-12-13
2019-12-13
2020-05-11
2020-07-07
2020-11-11
2021-02-24
2012-12-06
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-21
2013-06-18
2013-07-25
2013-08-08
2013-08-22
2013-09-11
2013-09-26
2013-10-30
2013-11-20
2013-12-23
2014-01-17
2014-02-26
2014-08-05
2014-09-08
2014-10-21

Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Iwanuma (Abukuma)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)

Activity insuspended
sediments (Bq/kg)
1.39E+03
1.47E+02
2.10E+03
2.93E+03
2.93E+02
2.15E+3
1.81E+3
1.35E+3
6.96E+2
1.10E+3
7.24E+2
7.79E+2
1.13E+3
5.26E+2
6.41E+2
4.87E+2
6.38E+2
1.21E+3
7.15E+2
9.40E+2
7.52E+2
1.01E+3
7.34E+2
8.43E+2
8.05E+2
4.11E+2
4.69E+2
3.00E+2
8.59E+2
5.48E+2
9.05E+2
2.98E+04
3.09E+04
1.26E+04
1.83E+04
2.09E+04
2.14E+04
1.67E+04
3.90E+03
3.47E+04
3.28E+04
2.38E+03
3.39E+04
2.53E+04
2.28E+04
2.48E+04
2.25E+04
9.29E+03
1.48E+04
1.43E+04
2.04E+03
1.80E+04

Standard
deviation
3.40E+01
4.50E+01
6.20E+01
8.60E+01
5.40E+01
9.40E+1
1.09E+2
7.50E+1
2.10E+1
1.90E+1
4.30E+1
3.80E+1
1.80E+1
9.00E+02.80E+1
3.60E+1
2.10E+1
5.00E+1
1.80E+1
1.20E+1
2.40E+1
2.90E+1
8.10E+1
5.10E+1
6.90E+1
1.40E+1
1.30E+1
9.00E+0
2.60E+1
2.60E+1
3.70E+1
8.30E+02
7.61E+02
1.90E+02
2.00E+02
5.34E+02
5.62E+02
3.96E+02
1.77E+02
2.84E+02
1.04E+03
7.33E+02
9.84E+02
5.46E+02
4.14E+02
5.50E+02
5.48E+02
2.62E+02
5.07E+02
2.85E+02
2.75E+02
3.52E+02

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

75.6

498.7

63

Table II.1. (cont.)
Sampling
date

Site(river name)2014-12-04
2015-01-14
2015-04-17
2015-06-02
2015-07-22
2015-08-25
2016-02-16
2016-04-08
2016-06-21
2016-07-28
2016-10-17
2016-12-20
2017-02-27
2017-05-11
2017-07-06
2017-12-04
2018-05-31
2018-07-02
2018-10-11
2018-12-04
2019-04-25
2019-07-05
2020-02-17
2020-05-14
2020-07-07
2020-10-14
2021-02-02
2011-09-26
2012-12-06
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-22
2013-06-18
2013-07-25
2013-08-08
2013-08-22
2013-09-11
2013-09-26
2013-10-30
2013-11-20
2013-12-23
2014-01-17
2014-02-26
2014-08-05
2014-09-08
2014-10-21
2014-12-04
2015-01-14
2015-04-17

Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Mano (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)64

Activity insuspended
sediments (Bq/kg)
1.37E+03
1.10E+03
1.83E+4
1.33E+4
1.50E+4
1.76E+4
2.69E+3
3.11E+3
7.41E+3
6.62E+3
6.39E+3
3.89E+3
1.01E+3
3.50E+3
8.78E+3
7.83E+3
7.37E+3
1.99E+2
7.99E+3
8.50E+3
1.29E+4
7.07E+3
4.67E+3
3.62E+3
3.76E+3
3.88E+3
2.84E+3
2.81E+04
7.78E+03
6.30E+03
7.07E+03
6.71E+03
6.13E+03
6.51E+03
5.85E+03
6.30E+03
6.18E+03
7.67E+03
7.32E+03
5.64E+03
8.42E+03
7.20E+03
7.08E+03
5.41E+03
1.35E+03
4.69E+03
6.26E+03
5.69E+03
4.89E+03
4.81E+03
9.10E+01
4.25E+3Standard
deviation

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

110.8

405.5

3.46E+02
2.40E+02
2.77E+2
4.11E+2
2.56E+2
2.04E+2
6.18E+2
1.37E+2
1.32E+2
3.22E+2
1.06E+2
1.01E+2
2.74E+2
1.39E+3
2.70E+1
2.00E+2
6.40E+1
5.50E+1
4.62E+2
8.24E+2
1.57E+2
6.70E+1
6.30E+1
6.10E+1
6.10E+1
1.00E+2
4.34E+02
2.88E+02
2.38E+02
2.40E+02
2.26E+02
1.09E+02
1.29E+02
7.80E+01
3.41E+02
8.70E+01
2.69E+02
1.54E+02
2.29E+02
2.34E+02
1.64E+02
1.81E+02
1.63E+02
1.30E+01
1.11E+02
9.20E+01
1.70E+02
1.37E+02
1.01E+02
3.36E+02
1.25E+2

Table II.1. (cont.)
Sampling
date

Site(river name)2015-06-17
2015-07-22
2015-08-25
2015-11-05
2015-11-24
2016-02-16
2016-04-11
2016-06-21
2016-07-28
2016-10-17
2016-12-20
2017-02-27
2017-05-11
2017-07-06
2017-12-04
2018-05-31
2018-07-02
2018-10-11
2018-12-04
2019-04-25
2019-07-05
2019-12-19
2020-02-17
2020-05-14
2020-07-07
2020-10-14
2021-02-02
2011-09-27
2012-12-08
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-17
2013-05-20
2013-06-17
2013-08-08
2013-08-22
2013-09-11
2013-09-25
2013-10-29
2013-12-23
2014-01-15
2014-02-24
2014-09-08
2014-10-20
2014-12-03
2015-01-13
2015-05-01
2015-06-03
2015-08-04
2015-09-01

Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Ojimadazeki (Mano)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)

Activity insuspended
sediments (Bq/kg)
3.88E+3
4.18E+3
3.66E+3
4.96E+3
3.06E+3
3.10E+3
8.21E+2
2.08E+3
2.56E+3
2.15E+3
2.62E+3
2.06E+3
2.62E+3
2.17E+3
2.68E+3
1.35E+3
1.33E+3
1.75E+3
2.11E+3
1.49E+3
1.51E+3
1.12E+3
7.29E+2
4.10E+2
1.25E+3
6.21E+2
1.22E+3
1.61E+03
1.12E+03
2.06E+02
4.30E+02
3.69E+02
3.66E+02
9.00E+02
3.53E+02
9.23E+02
1.04E+03
4.57E+02
8.47E+02
4.33E+02
7.47E+02
2.29E+02
2.59E+03
3.99E+02
8.12E+02
5.87E+02
5.93E+02
2.57E+02
6.33E+2
2.19E+2
9.61E+2
2.78E+2Standard
deviation
1.37E+2
7.40E+1
9.40E+1
5.90E+1
2.40E+1
8.10E+1
8.50E+1
1.85E+2
1.07E+2
5.30E+1
1.25E+2
1.66E+2
6.90E+1
2.60E+1
2.00E+1
2.20E+1
2.30E+1
1.90E+1
1.21E+2
1.38E+2
1.06E+2
2.30E+1
2.20E+1
8.00E+0
7.80E+1
1.50E+1
7.00E+1
7.00E+01
5.30E+01
1.10E+01
1.90E+01
1.80E+01
7.00E+00
5.00E+00
5.00E+00
4.20E+01
2.20E+01
1.50E+01
2.10E+01
1.20E+01
2.30E+01
1.40E+01
5.10E+01
1.10E+01
4.00E+01
1.70E+01
2.00E+01
9.00E+00
2.60E+1
1.00E+1
7.90E+1
2.30E+1

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

570.9

40.0

65

Table II.1. (cont.)
Sampling
date

Site(river name)2015-10-13
2015-11-25
2016-01-14
2016-02-22
2016-04-07
2016-06-07
2016-08-02
2016-09-30
2017-01-19
2017-02-27
2017-05-11
2017-07-10
2017-09-20
2017-12-11
2018-05-28
2018-07-02
2018-10-12
2018-12-04
2019-04-23
2019-07-03
2020-05-13
2020-07-09
2020-10-15
2021-02-04
2012-12-08
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-17
2013-05-20
2013-06-17
2013-07-25
2013-08-08
2013-08-22
2013-10-29
2013-12-23
2014-01-15
2014-02-24
2014-08-08
2014-09-08
2014-10-20
2014-12-03
2015-01-13
2015-05-01
2015-06-03
2015-08-04
2015-09-01
2015-10-13
2015-11-25
2016-01-14
2016-02-22

Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Matsubara (Same)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)

66

Activity insuspended
sediments (Bq/kg)
4.07E+2
1.18E+2
2.92E+2
3.45E+2
2.12E+2
2.04E+2
1.81E+2
3.36E+2
4.29E+2
1.40E+2
3.53E+2
5.98E+2
4.90E+2
4.87E+2
1.85E+2
2.37E+2
1.99E+2
1.43E+2
1.45E+2
1.86E+2
1.20E+2
1.79E+2
2.90E+2
1.74E+2
2.38E+03
1.33E+03
1.35E+03
1.29E+03
1.44E+03
1.19E+03
1.33E+03
2.12E+03
7.51E+02
7.23E+02
9.90E+02
1.28E+03
7.98E+02
4.40E+02
1.10E+03
7.59E+02
6.96E+02
7.11E+02
8.33E+02
5.73E+02
9.80E+2
5.71E+2
6.68E+2
9.86E+2
7.05E+2
3.73E+2
4.44E+2
2.32E+2Standard
deviation
1.70E+1
1.20E+1
2.10E+1
1.90E+1
5.40E+1
4.60E+1
2.10E+1
3.00E+1
3.90E+1
4.40E+1
2.70E+1
2.80E+1
1.90E+1
1.90E+1
2.00E+1
1.20E+1
1.60E+1
5.90E+1
2.60E+1
2.90E+1
2.00E+0
4.00E+0
7.00E+0
6.00E+09.90E+01
2.80E+01
4.80E+01
2.70E+01
1.80E+01
4.20E+01
3.80E+01
1.03E+02
3.10E+01
7.00E+00
3.20E+01
3.60E+01
1.90E+01
1.30E+01
2.50E+01
2.90E+01
2.60E+01
2.60E+01
2.60E+01
1.60E+01
2.50E+1
3.80E+1
3.70E+1
5.20E+1
3.00E+1
2.60E+1
1.10E+1
1.60E+1

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

70.1

38.8

Table II.1. (cont.)
Sampling
date

Site(river name)2016-04-07
2016-06-07
2016-08-02
2016-09-30
2017-01-19
2017-02-27
2017-05-11
2017-07-10
2017-09-20
2017-12-11
2018-05-28
2018-07-02
2018-10-12
2019-04-23
2019-07-03
2020-05-13
2020-07-09
2020-10-15
2021-02-04
2011-08-31
2011-09-26
2012-12-19
2013-01-11
2013-01-23
2013-02-27
2013-04-18
2013-05-21
2013-06-18
2013-08-09
2013-08-23
2013-09-13
2013-09-27
2013-10-31
2013-11-21
2013-12-25
2014-01-15
2014-02-25
2014-08-07
2014-09-10
2014-10-21
2014-12-04
2015-01-14
2015-04-23
2015-05-27
2015-07-22
2015-08-25
2015-10-09
2016-01-20
2016-02-15
2016-02-15
2016-04-19
2016-04-19

Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Onahama (Fujiwara)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)

Activity insuspended
sediments (Bq/kg)
2.48E+2
6.88E+2
4.68E+2
5.85E+2
7.42E+2
4.45E+2
5.23E+2
5.22E+2
4.78E+2
5.99E+2
4.75E+2
4.90E+2
4.70E+2
3.68E+2
1.05E+3
7.66E+2
4.55E+2
5.90E+2
4.02E+2
2.07E+04
7.37E+03
8.60E+03
9.11E+03
1.01E+04
6.36E+03
6.69E+03
4.82E+03
8.75E+03
5.20E+03
6.60E+03
8.82E+03
4.17E+03
1.69E+03
2.18E+03
1.26E+04
3.53E+03
3.26E+03
1.57E+03
4.43E+02
2.51E+03
3.07E+03
2.13E+03
1.84E+3
8.69E+2
1.63E+3
1.90E+3
3.37E+3
9.11E+2
3.12E+2
4.74E+2
4.94E+2
3.21E+2Standard
deviation
2.10E+1
4.00E+1
3.20E+1
4.00E+1
4.40E+1
3.30E+1
2.50E+1
2.80E+1
2.40E+1
1.60E+1
1.30E+1
2.00E+1
2.10E+1
4.30E+1
7.00E+1
6.80E+1
1.70E+1
1.80E+1
2.30E+1
2.00E+02
1.68E+02
9.30E+01
9.10E+01
2.52E+02
1.53E+02
1.62E+02
1.67E+02
3.62E+02
1.93E+02
1.32E+02
2.99E+02
1.02E+02
5.70E+01
6.90E+01
3.22E+02
1.24E+02
8.50E+01
3.90E+01
6.50E+01
6.50E+01
6.00E+01
5.30E+01
3.50E+1
3.70E+1
4.20E+1
9.10E+1
7.00E+1
3.20E+1
2.50E+1
1.50E+1
2.60E+1
1.50E+1

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

83.6

222.8

67

Table II.1. (cont.)
Sampling
date

Site(river name)2016-05-31
2016-05-31
2016-08-09
2016-08-09
2017-05-08
2017-05-22
2017-12-07
2018-05-28
2018-06-01
2018-12-05
2019-04-23
2019-07-03
2020-07-08
2011-08-31
2011-10-18
2012-12-07
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-18
2013-05-21
2013-06-18
2013-09-13
2013-09-27
2013-11-20
2013-12-24
2014-01-16
2014-02-25
2014-08-05
2015-01-14
2015-05-28
2015-07-23
2015-10-08
2015-12-04
2016-01-26
2016-02-26
2016-04-13
2016-06-10
2016-10-24
2016-12-21
2017-03-02
2017-05-09
2017-07-07
2017-09-25
2017-12-08
2018-05-31
2018-07-03
2018-10-17
2018-12-03
2019-04-24
2019-08-06

Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Tsukidate (Hirose)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)

68

Activity insuspended
sediments (Bq/kg)
9.35E+2
1.25E+3
3.01E+2
2.57E+3
1.16E+3
1.14E+3
2.27E+3
1.52E+3
2.47E+3
1.78E+3
1.88E+3
4.20E+3
8.51E+2
3.05E+04
2.09E+04
5.42E+03
5.34E+03
7.75E+02
3.66E+03
7.19E+03
3.60E+03
7.48E+03
5.48E+03
2.46E+03
1.64E+03
1.12E+02
4.02E+03
2.67E+02
1.66E+03
2.03E+03
2.25E+03
1.93E+3
1.74E+3
1.65E+3
9.15E+2
1.71E+3
2.70E+3
3.32E+3
2.88E+3
1.54E+3
2.06E+3
1.95E+3
6.85E+2
1.92E+3
2.54E+3
6.63E+2
7.56E+2
2.49E+3
1.05E+3
6.19E+2
2.14E+3
1.77E+3Standard
deviation
2.90E+1
4.20E+1
1.40E+1
7.10E+1
3.80E+1
4.00E+1
3.80E+1
2.30E+1
2.10E+1
5.20E+1
6.70E+1
2.43E+2
1.80E+1
2.36E+02
1.84E+02
2.40E+02
2.77E+02
2.39E+02
7.60E+01
1.92E+02
1.52E+02
2.22E+02
2.09E+02
1.14E+02
5.60E+01
4.20E+01
9.80E+01
9.30E+01
6.00E+01
4.40E+01
7.40E+01
4.00E+1
6.90E+1
3.40E+1
5.60E+1
5.30E+1
7.40E+1
2.81E+2
1.02E+2
4.10E+1
7.20E+1
1.23E+2
3.00E+1
3.20E+1
3.80E+1
2.00E+1
2.10E+1
4.50E+1
2.80E+1
8.20E+1
2.00E+2
9.40E+1

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

2380

81.8

Table II.1. (cont.)
Sampling
date

Site(river name)2019-12-13
2020-02-19
2020-05-12
2020-07-10
2020-08-17
2020-11-11
2021-02-05
2011-09-01
2011-09-27
2012-12-07
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-17
2013-05-20
2013-06-17
2013-07-25
2013-08-22
2013-09-13
2013-09-25
2013-11-20
2013-12-23
2014-01-16
2014-02-25
2014-08-06
2014-12-05
2015-01-14
2015-05-01
2015-05-28
2015-07-23
2015-08-27
2015-10-06
2015-12-04
2016-01-28
2016-02-22
2016-04-13
2016-06-10
2016-08-05
2017-05-15
2017-07-10
2017-09-06
2017-12-12
2018-05-31
2018-07-04
2018-10-17
2018-12-03
2019-04-25
2019-08-06
2020-11-11
2021-02-01
2012-12-18

Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Nihonmatsu (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Miyota (Abukuma)
Nishikawa (Shakado)

Activity insuspended
sediments (Bq/kg)
3.32E+2
6.91E+2
7.54E+2
6.70E+2
3.61E+2
1.06E+3
8.38E+2
1.48E+02
3.75E+03
1.92E+03
2.60E+03
2.78E+03
6.27E+02
3.23E+02
3.05E+03
2.76E+03
1.68E+03
8.15E+02
1.94E+03
2.97E+02
4.07E+02
3.93E+02
8.78E+02
9.27E+02
9.92E+02
9.13E+02
1.59E+03
4.69E+03
1.36E+3
3.14E+3
6.29E+2
2.48E+3
4.97E+2
6.70E+2
1.21E+3
3.27E+2
2.85E+3
6.46E+2
1.48E+3
9.90E+2
2.40E+3
1.30E+3
7.34E+2
3.09E+2
8.08E+2
6.67E+2
1.69E+3
1.65E+3
7.87E+2
6.82E+2
4.80E+2
3.29E+03

Standard
deviation
1.10E+1
4.00E+1
4.20E+1
2.20E+1
9.00E+0
7.30E+1
8.70E+1
3.28E+02
9.80E+01
8.70E+01
2.27E+02
4.70E+01
2.90E+01
9.20E+01
7.80E+01
1.00E+02
6.10E+01
1.36E+02
7.50E+01
1.04E+02
1.10E+01
1.10E+01
1.00E+01
1.40E+01
3.90E+01
3.00E+01
5.00E+01
1.73E+02
4.40E+1
1.49E+2
2.00E+1
1.23E+2
1.70E+1
1.30E+1
4.30E+1
2.20E+1
1.62E+2
1.40E+1
6.60E+1
4.30E+1
7.40E+1
2.60E+1
1.60E+1
9.00E+0
3.20E+1
1.70E+1
9.20E+1
4.30E+1
3.80E+1
2.70E+1
4.20E+1
1.77E+02

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

1287

74.1

289.4

132.0

69

Table II.1. (cont.)
Sampling
date

Site(river name)2013-01-10
2013-01-22
2013-02-26
2013-04-17
2013-05-20
2013-06-17
2013-07-25
2013-08-08
2013-08-22
2013-09-12
2013-09-26
2013-10-29
2013-11-20
2013-12-23
2014-01-16
2014-02-25
2014-08-07
2014-09-08
2014-10-20
2014-12-03
2015-01-14
2015-05-01
2015-05-28
2015-07-23
2015-08-27
2015-10-06
2015-12-04
2016-01-28
2016-02-22
2016-04-07
2016-05-27
2016-12-20
2017-02-27
2017-05-11
2017-09-06
2019-04-25
2019-08-06
2020-11-11
2021-02-01
2011-09-26
2012-12-06
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-21
2013-06-18
2013-07-25
2013-08-08
2013-08-22
2013-09-11

Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Nishikawa (Shakado)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)

70

Activity insuspended
sediments (Bq/kg)
3.68E+03
3.47E+03
4.37E+03
2.92E+03
1.57E+03
2.96E+03
4.11E+03
1.98E+03
3.49E+03
2.16E+03
7.16E+02
3.16E+02
3.25E+03
4.55E+03
1.46E+02
3.78E+03
4.96E+02
1.30E+01
3.14E+02
1.93E+03
2.08E+03
1.49E+3
9.84E+2
1.03E+3
2.86E+3
1.42E+3
1.94E+3
1.46E+3
1.18E+3
9.86E+2
2.84E+3
1.54E+3
2.46E+2
2.04E+3
2.11E+3
7.45E+2
1.31E+3
6.25E+2
9.07E+2
4.22E+04
2.67E+04
2.11E+04
2.28E+04
2.73E+04
2.24E+04
2.75E+04
2.55E+04
2.46E+04
2.49E+04
2.64E+04
2.32E+04
2.24E+04

Standard
deviation
1.29E+02
1.47E+02
1.39E+02
7.00E+01
4.30E+01
1.46E+02
1.14E+02
5.00E+01
9.90E+01
4.70E+01
2.20E+01
1.00E+01
8.50E+01
1.07E+02
4.90E+01
9.00E+01
1.50E+01
3.30E+01
9.00E+00
4.80E+01
6.90E+01
4.20E+1
2.90E+1
2.80E+1
1.31E+2
3.70E+1
1.03E+2
8.00E+1
1.80E+2
7.30E+1
1.79E+2
3.10E+1
1.80E+1
1.04E+2
2.60E+1
6.20E+1
5.10E+1
4.20E+1
3.90E+1
8.99E+02
9.45E+02
3.01E+02
7.73E+02
3.76E+02
3.64E+02
4.37E+02
1.22E+02
7.50E+02
8.59E+02
5.18E+02
2.84E+02
5.63E+02

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

35.8

565.0

Table II.1. (cont.)
Sampling
date

Site(river name)2013-09-26
2013-10-30
2013-11-20
2013-12-23
2014-01-17
2014-02-26
2014-08-06
2014-09-09
2014-10-21
2014-12-04
2015-01-14
2015-04-17
2015-06-17
2015-07-28
2015-08-28
2015-10-23
2015-12-21
2016-02-16
2016-04-08
2016-06-10
2016-08-19
2016-12-20
2017-03-02
2017-05-09
2017-07-07
2017-09-06
2018-05-31
2018-07-02
2018-10-11
2018-12-04
2019-04-25
2019-07-03
2020-10-14
2021-02-02
2011-08-31
2011-09-26
2012-02-24
2012-12-05
2012-12-19
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-21
2013-06-18
2013-08-09
2013-08-23
2013-09-13
2013-09-27
2013-10-31
2013-11-21
2013-12-25

Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kitamachi (Mizunashi)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)

Activity insuspended
sediments (Bq/kg)
1.80E+04
2.05E+04
2.94E+04
2.13E+04
2.56E+04
1.96E+04
1.44E+04
1.32E+04
9.03E+03
1.60E+04
1.38E+04
8.28E+3
1.34E+4
7.25E+3
9.52E+3
1.89E+3
6.06E+3
6.44E+3
6.15E+3
6.05E+3
7.92E+3
7.03E+3
5.62E+3
4.11E+3
5.76E+3
6.58E+3
4.78E+3
4.28E+3
5.11E+3
5.56E+3
5.00E+3
4.95E+3
1.56E+3
1.13E+3
2.52E+04
1.30E+03
2.26E+04
7.41E+03
1.27E+04
6.47E+03
6.76E+03
1.10E+04
8.75E+03
5.90E+03
1.11E+04
1.03E+04
6.37E+03
6.45E+03
2.00E+00
4.35E+03
4.42E+03
4.89E+03

Standard
deviation
3.50E+02
1.95E+02
7.51E+02
4.81E+02
5.03E+02
3.43E+02
2.82E+02
1.70E+02
1.67E+02
3.73E+02
4.42E+02
6.40E+1
9.90E+1
7.80E+1
9.10E+1
2.90E+1
1.09E+2
1.34E+2
2.59E+2
1.90E+2
1.53E+2
2.65E+2
2.78E+2
1.33E+2
8.50E+1
6.70E+1
6.00E+1
4.00E+1
4.70E+1
8.90E+1
1.26E+2
1.17E+2
5.40E+1
2.40E+1
3.37E+02
3.41E+02
4.70E+02
3.15E+02
1.67E+02
2.55E+02
3.08E+02
4.21E+02
3.03E+02
1.80E+02
5.00E+02
3.66E+02
1.75E+02
2.50E+02
7.10E+01
9.20E+01
1.14E+02
5.40E+01

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

56.6

229.1

71

Table II.1. (cont.)
Sampling
date

Site(river name)2014-01-15
2014-02-25
2014-08-07
2014-09-10
2014-10-21
2014-12-04
2015-01-15
2015-04-23
2015-05-27
2015-07-24
2015-08-28
2015-10-09
2016-02-15
2016-04-19
2016-05-31
2016-08-09
2016-10-03
2016-12-21
2017-03-01
2017-05-08
2017-07-04
2017-09-04
2017-12-07
2018-05-28
2018-07-04
2018-10-11
2018-12-03
2019-04-23
2019-07-03
2012-12-07
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-17
2013-05-20
2013-06-17
2013-09-12
2013-09-25
2013-11-19
2013-12-24
2014-01-16
2014-02-25
2014-08-04
2014-10-20
2014-12-03
2015-01-13
2015-06-02
2015-07-15
2015-08-24
2015-10-14
2016-01-15

Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Kawamata (Hirose)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)

72

Activity insuspended
sediments (Bq/kg)
1.51E+03
3.00E+03
1.26E+02
2.60E+01
1.33E+03
3.58E+03
4.49E+03
2.91E+3
3.40E+3
3.23E+3
3.69E+3
8.37E+2
6.39E+2
7.73E+2
2.31E+3
1.59E+3
8.93E+2
1.53E+3
1.20E+3
1.09E+3
9.24E+2
1.28E+3
2.71E+3
5.85E+2
1.52E+3
1.72E+3
1.58E+3
1.59E+3
1.76E+3
5.30E+01
4.91E+03
3.23E+03
2.66E+03
4.17E+03
4.43E+03
3.11E+03
2.54E+03
4.11E+03
1.36E+03
1.26E+03
8.83E+02
9.51E+02
2.96E+02
2.06E+03
2.03E+03
1.43E+03
5.64E+03
1.56E+3
1.26E+3
1.21E+3
1.22E+3
7.91E+2Standard
deviation
2.70E+01
7.50E+01
3.70E+01
6.30E+01
2.90E+01
9.70E+01
8.40E+01
4.30E+1
6.30E+1
4.80E+1
4.80E+1
1.60E+1
4.30E+1
5.80E+1
7.10E+1
4.80E+1
2.50E+1
3.90E+1
5.90E+1
4.40E+1
5.70E+1
2.90E+1
5.40E+1
1.50E+1
3.30E+1
3.40E+1
6.40E+1
7.40E+1
6.60E+1
2.31E+02
1.42E+02
1.56E+02
5.00E+01
1.07E+02
1.33E+02
1.07E+02
1.14E+02
9.00E+01
3.50E+01
3.50E+01
2.40E+01
2.30E+01
7.90E+01
6.50E+01
5.80E+01
1.80E+01
1.90E+02
4.30E+1
4.60E+1
2.30E+1
3.40E+1
3.00E+1

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

4123

105.1

Table II.1. (cont.)
Sampling
date

Site(river name)2016-04-11
2016-05-30
2016-07-28
2016-10-17
2017-01-06
2017-02-27
2017-05-11
2017-07-06
2019-04-09
2019-08-05
2021-02-02
2012-12-07
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-17
2013-05-20
2013-06-17
2013-07-26
2013-08-09
2013-08-23
2013-09-11
2013-09-25
2013-10-31
2013-11-19
2013-12-24
2014-01-16
2014-02-25
2014-08-04
2014-09-08
2014-10-20
2014-12-03
2015-01-13
2015-05-27
2015-07-15
2015-08-24
2015-10-08
2016-01-26
2016-02-26
2016-04-13
2017-03-02
2017-05-09
2017-07-07
2017-09-25
2017-12-08
2019-04-24
2019-08-05
2020-02-19
2020-07-10
2021-02-05
2012-12-07

Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Marumori (Abukuma)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Senoue (Surikami)
Yagita (Ara)

Activity insuspended
sediments (Bq/kg)
7.17E+2
1.58E+3
1.08E+3
1.03E+3
5.83E+2
3.09E+2
5.51E+2
8.41E+2
8.76E+2
9.11E+2
1.92E+2
5.00E+03
4.02E+03
3.18E+02
3.00E+03
3.81E+03
3.50E+03
3.34E+03
2.54E+03
2.67E+02
4.65E+03
2.53E+03
7.85E+03
1.67E+03
1.13E+03
1.12E+02
2.98E+03
5.02E+03
1.45E+03
1.19E+03
4.09E+02
1.28E+02
1.46E+03
1.48E+03
1.17E+3
1.86E+3
3.03E+3
1.22E+3
1.91E+3
1.19E+3
9.18E+2
5.62E+2
7.81E+2
1.58E+3
1.95E+3
4.69E+2
1.71E+3
1.19E+3
4.04E+2
1.02E+3
2.65E+2
2.76E+03

Standard
deviation
6.30E+1
5.50E+1
4.30E+1
2.00E+1
2.20E+1
3.60E+1
2.10E+1
1.60E+1
2.90E+1
4.20E+1
3.40E+1
2.62E+02
1.39E+02
1.31E+02
1.07E+02
8.30E+01
1.13E+02
8.70E+01
8.10E+01
8.40E+01
1.02E+02
7.00E+01
1.55E+02
4.30E+01
3.00E+01
4.20E+01
6.10E+01
1.93E+02
4.60E+01
3.40E+01
1.45E+02
4.00E+01
3.20E+01
3.30E+01
5.40E+1
1.43E+2
1.31E+2
2.10E+1
7.10E+1
8.00E+1
6.80E+1
3.80E+1
3.40E+1
8.10E+1
3.00E+1
1.30E+1
1.04E+2
1.08E+2
1.00E+1
2.60E+1
1.10E+1
1.88E+02

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

313.3

41.9

184.6

52.7

73

Table II.1. (cont.)
Sampling
date

Site(river name)2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-17
2013-05-20
2013-06-17
2013-07-26
2013-08-08
2013-08-23
2013-09-12
2013-09-25
2013-12-24
2014-01-16
2014-02-25
2014-08-04
2014-09-10
2014-10-20
2014-12-05
2015-01-15
2015-04-24
2015-05-27
2015-07-15
2015-08-24
2015-11-05
2016-02-26
2016-04-13
2012-12-07
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-17
2013-05-20
2013-06-19
2013-07-26
2013-08-10
2013-08-24
2013-09-11
2013-09-25
2013-11-19
2013-12-24
2014-01-16
2014-02-25
2014-08-04
2014-09-11
2014-10-20
2014-12-03
2015-01-13
2015-04-24
2015-05-27
2015-07-15

Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Yagita (Ara)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)

74

Activity insuspended
sediments (Bq/kg)
3.13E+03
1.46E+03
1.50E+03
1.13E+03
5.80E+03
2.06E+03
1.02E+02
9.25E+03
1.16E+04
3.82E+02
1.03E+04
1.63E+03
2.72E+03
1.88E+02
5.54E+03
9.23E+02
2.96E+03
1.47E+03
3.81E+03
2.31E+03
7.80E+3
1.63E+3
1.90E+3
1.11E+4
1.04E+3
1.90E+3
1.67E+3
8.16E+03
1.27E+02
7.62E+02
2.03E+04
1.28E+04
4.84E+03
6.62E+02
1.28E+03
5.43E+03
4.83E+03
4.27E+03
3.03E+02
1.71E+03
2.26E+03
3.06E+03
2.59E+03
1.86E+03
3.03E+03
2.90E+03
6.24E+02
2.23E+03
1.79E+03
1.96E+3
3.47E+3
4.57E+3Standard
deviation

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

2921

103.4

1.30E+02
5.00E+01
5.80E+01
1.62E+02
3.60E+01
2.90E+01
2.47E+02
2.76E+02
1.07E+02
2.30E+02
4.20E+01
9.10E+01
4.20E+01
1.71E+02
3.10E+01
7.50E+01
3.70E+01
1.08E+02
6.40E+01
2.74E+2
8.50E+1
1.03E+2
2.64E+2
2.00E+1
6.50E+1
5.60E+1
3.33E+02
4.40E+01
2.71E+02
3.58E+02
3.66E+02
1.98E+02
1.73E+02
2.70E+01
8.30E+01
1.12E+02
1.07E+02
9.30E+01
6.00E+01
6.00E+01
7.00E+01
7.20E+01
4.60E+01
8.90E+01
8.40E+01
2.00E+01
5.30E+01
5.50E+01
4.00E+1
1.47E+2
1.08E+2

Table II.1. (cont.)
Sampling
date

Site(river name)2015-08-24
2015-10-08
2016-01-20
2016-02-26
2016-04-13
2017-03-02
2017-05-09
2017-07-07
2017-09-25
2019-04-24
2020-09-04
2020-11-11
2021-02-05
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-17
2013-05-20
2013-06-17
2013-07-25
2013-08-08
2013-08-22
2013-09-12
2013-09-26
2013-10-30
2013-11-20
2013-12-24
2014-01-16
2014-02-25
2014-08-06
2014-09-09
2014-10-22
2014-12-05
2015-01-14
2015-05-01
2015-05-28
2015-07-23
2015-08-27
2015-10-06
2015-12-04
2016-01-28
2016-02-16
2016-04-13
2016-06-10
2016-08-05
2016-09-29
2016-12-20
2017-02-27
2017-05-09
2017-07-10
2017-09-06

Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Kuroiwa (Abukuma)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)

Activity insuspended
sediments (Bq/kg)
5.32E+2
8.09E+2
1.54E+3
6.27E+2
5.33E+2
8.04E+2
2.10E+3
2.70E+3
2.86E+3
1.51E+3
9.31E+2
1.10E+3
4.27E+2
2.10E+04
1.68E+04
4.78E+02
5.17E+04
1.04E+04
4.54E+03
1.41E+04
1.38E+04
4.82E+03
7.51E+03
7.75E+03
4.60E+01
8.42E+03
1.53E+04
1.70E+04
1.55E+04
1.63E+02
3.89E+03
6.22E+03
4.00E+03
9.15E+03
3.30E+03
7.85E+3
3.70E+3
5.77E+3
5.90E+3
2.85E+3
1.58E+3
1.89E+3
4.78E+3
3.79E+3
5.40E+3
5.91E+3
3.38E+3
4.81E+3
1.22E+3
3.08E+3
4.60E+3
2.67E+3Standard
deviation
1.60E+1
2.00E+1
4.50E+1
4.80E+1
2.30E+1
7.20E+1
8.20E+1
5.00E+1
3.70E+1
7.20E+1
2.30E+1
2.70E+1
5.50E+1
4.76E+02
3.83E+02
7.22E+02
5.05E+02
2.34E+02
9.80E+01
6.97E+02
9.00E+01
1.54E+02
2.05E+02
1.48E+02
8.90E+01
2.00E+02
5.42E+02
3.45E+02
5.01E+02
7.90E+01
9.70E+01
1.23E+02
8.30E+01
2.23E+02
1.10E+02
1.41E+2
8.30E+1
1.24E+2
1.30E+2
6.00E+1
6.00E+1
4.40E+1
1.10E+2
1.42E+2
2.68E+2
1.03E+2
1.10E+2
2.80E+2
4.20E+1
1.12E+2
1.10E+2
1.18E+2

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

72.6

98.5

75

Table II.1. (cont.)
Sampling
date

Site(river name)2017-12-12
2018-05-31
2018-07-04
2019-04-25
2019-07-05
2019-11-15
2020-02-26
2020-05-12
2020-07-06
2020-11-11
2021-02-01
2012-12-06
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-21
2013-06-18
2013-07-25
2013-08-08
2013-08-22
2013-09-11
2013-09-26
2013-10-30
2013-11-20
2013-12-23
2014-01-17
2014-02-26
2014-08-06
2014-09-09
2014-10-21
2014-12-04
2015-01-14
2015-04-30
2015-06-17
2015-07-27
2015-09-02
2016-02-22
2016-04-08
2016-06-10
2016-10-27
2016-12-20
2017-03-02
2017-05-09
2017-07-10
2017-09-06
2017-12-11
2018-05-31
2018-07-02
2018-10-12
2018-12-04

Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Tomita (Ouse)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)

76

Activity insuspended
sediments (Bq/kg)
9.77E+2
1.43E+3
2.49E+3
4.03E+3
3.07E+3
1.36E+3
1.26E+4
5.71E+2
2.39E+3
1.84E+3
1.80E+3
5.13E+04
7.50E+03
3.88E+04
6.70E+04
7.50E+03
3.76E+04
1.53E+04
2.83E+04
5.34E+04
5.29E+04
9.06E+04
1.03E+04
4.91E+04
3.58E+03
3.76E+04
2.96E+04
5.48E+04
2.51E+04
4.02E+04
3.64E+04
3.91E+04
2.84E+04
3.75E+04
2.17E+4
2.89E+4
2.77E+4
3.15E+4
1.15E+4
1.54E+4
2.33E+4
1.82E+4
7.86E+3
7.29E+3
7.81E+3
9.70E+3
1.03E+4
7.66E+3
1.29E+4
1.17E+4
1.48E+4
1.74E+4Standard
deviation

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

2.50E+1
2.30E+1
3.30E+1
1.29E+2
1.22E+2
2.70E+1
2.56E+2
1.40E+1
5.30E+1
3.40E+1
1.03E+2
1.32E+03

49.9

1768

1.09E+03
2.84E+03
1.93E+03
2.89E+02
7.50E+01
6.99E+02
6.30E+02
2.09E+02
2.30E+02
1.51E+03
3.45E+02
8.50E+02
7.24E+02
4.83E+02
1.77E+02
1.29E+03
7.88E+02
1.04E+03
2.82E+02
1.10E+03
3.27E+2
4.90E+2
3.79E+2
3.69E+2
3.11E+2
2.16E+2
1.20E+3
1.63E+2
3.33E+2
4.31E+2
3.06E+2
1.77E+2
1.34E+2
7.30E+1
4.49E+2
1.63E+2
1.70E+1
5.56E+2

Table II.1. (cont.)
Sampling
date

Site(river name)2019-04-18
2019-07-03
2020-02-17
2020-05-14
2020-07-09
2020-10-14
2021-02-04
2012-12-06
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-21
2013-06-18
2013-07-25
2013-08-08
2013-08-22
2013-09-11
2013-09-26
2013-10-30
2013-11-20
2013-12-23
2014-01-17
2014-02-26
2014-08-06
2014-09-09
2014-10-21
2014-12-04
2015-01-14
2015-04-30
2015-07-27
2015-09-01
2015-10-23
2015-12-21
2016-02-22
2016-04-08
2016-06-10
2016-10-27
2016-12-20
2017-03-02
2017-05-09
2017-07-10
2017-09-06
2017-12-11
2018-05-17
2018-07-02
2018-10-12
2018-12-04
2019-04-23
2019-07-03
2019-12-04

Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Ota (Ota)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)

Activity insuspended
sediments (Bq/kg)
1.34E+4
3.20E+3
2.14E+3
3.73E+3
5.70E+3
4.63E+3
6.57E+3
1.56E+04
7.85E+03
1.35E+04
1.38E+04
8.62E+03
1.49E+04
4.01E+03
1.43E+04
1.19E+04
1.94E+04
1.30E+04
1.36E+04
4.04E+04
1.73E+04
2.36E+04
1.63E+04
1.45E+04
1.48E+04
1.73E+04
2.23E+04
1.64E+04
1.28E+04
9.96E+03
1.64E+4
1.27E+4
1.16E+4
2.08E+4
3.59E+3
6.46E+3
2.61E+3
6.00E+3
1.71E+4
8.69E+3
3.65E+3
4.09E+3
1.17E+4
1.45E+4
1.35E+4
2.82E+3
5.07E+3
1.36E+4
5.62E+3
4.54E+3
4.94E+3
5.26E+3Standard
deviation
1.30E+3
7.90E+1
2.90E+1
5.00E+1
2.59E+2
1.38E+2
1.84E+2
7.50E+02
3.20E+02
3.62E+02
2.73E+02
2.70E+02
4.30E+02
5.80E+01
4.87E+02
8.60E+01
3.92E+02
3.81E+02
3.15E+02
6.83E+02
2.20E+02
4.25E+02
5.10E+02
3.93E+02
5.07E+02
3.60E+02
7.40E+02
3.72E+02
1.92E+02
2.91E+02
1.59E+2
2.09E+2
2.19E+2
1.58E+2
1.36E+2
9.90E+1
1.46E+2
4.40E+2
1.73E+2
3.59E+2
2.25E+2
1.65E+2
2.29E+2
1.18E+2
4.50E+1
4.90E+1
1.13E+2
1.91E+2
6.79E+2
5.75E+2
5.55E+2
4.30E+1

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

50.3

724.2

77

Table II.1. (cont.)
Sampling
date

Site(river name)2020-03-05
2020-05-14
2020-07-09
2020-10-14
2021-02-04
2012-12-08
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-04-17
2013-05-20
2013-06-17
2013-07-25
2013-08-08
2013-08-22
2013-09-11
2013-09-25
2013-12-23
2014-01-15
2014-02-24
2014-09-08
2014-12-03
2015-01-13
2015-04-30
2015-06-03
2015-08-03
2015-09-01
2015-10-13
2016-08-02
2016-12-20
2017-02-27
2017-05-11
2017-07-10
2017-09-20
2017-12-11
2018-05-28
2018-07-02
2018-10-12
2018-12-04
2019-04-23
2019-07-03
2020-02-18
2020-05-13
2020-07-09
2020-10-15
2021-02-04
2012-12-05
2012-12-18
2013-01-11
2013-01-23
2013-02-27

Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Odaka (Odaka)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Asamai (Asami)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)

78

Activity insuspended
sediments (Bq/kg)
1.28E+3
5.99E+2
7.96E+3
1.45E+3
2.41E+3
4.90E+03
1.07E+02
5.55E+03
2.53E+03
4.88E+03
2.21E+03
1.76E+03
2.04E+02
4.27E+03
4.08E+03
2.66E+03
4.74E+03
5.40E+03
2.80E+03
1.03E+03
1.09E+03
4.16E+03
2.63E+03
7.09E+02
9.69E+2
2.94E+3
2.92E+3
1.40E+3
8.86E+2
1.21E+2
8.54E+2
8.74E+2
7.96E+2
4.61E+2
2.23E+3
1.21E+3
4.44E+2
8.95E+2
1.53E+3
1.14E+3
9.27E+2
1.35E+4
2.42E+2
1.42E+2
7.36E+2
2.54E+2
7.47E+2
4.48E+04
2.48E+04
3.43E+04
1.45E+04
3.51E+04

Standard
deviation

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

1.40E+1
9.00E+0
7.40E+1
2.10E+1
4.10E+1
1.93E+02

25.8

193.8

25.4

951.5

1.64E+02
1.52E+02
6.50E+01
6.70E+01
6.90E+01
6.70E+01
7.70E+01
1.05E+02
3.00E+01
1.23E+02
2.10E+02
6.30E+01
7.00E+00
3.40E+01
1.19E+02
4.80E+01
4.60E+01
3.00E+1
1.35E+2
1.13E+2
6.60E+1
2.30E+1
6.00E+0
3.80E+1
5.70E+1
3.40E+1
1.90E+1
6.40E+1
1.90E+1
1.10E+1
1.60E+1
3.00E+1
8.60E+1
5.70E+1
7.45E+2
1.80E+1
4.00E+02.30E+1
9.00E+08.10E+1
1.03E+03
3.33E+02
8.87E+02
8.24E+02
8.64E+02

Table II.1. (cont.)
Sampling
date

Site(river name)2013-09-13
2013-09-27
2013-10-29
2013-11-21
2014-01-15
2014-02-26
2014-08-09
2014-09-10
2014-10-22
2014-12-05
2015-01-15
2015-04-22
2015-05-29
2015-07-21
2015-09-03
2015-10-22
2015-12-24
2016-01-21
2016-02-23
2016-04-15
2016-09-27
2016-12-21
2017-03-01
2017-04-19
2017-07-10
2017-09-05
2017-12-12
2018-05-30
2018-07-03
2018-12-03
2019-04-24
2019-07-05
2020-02-26
2020-05-15
2020-07-06
2020-10-21
2021-02-01
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-09-11
2013-09-25
2013-11-19
2014-01-15
2014-02-27
2014-08-08
2014-09-10
2014-12-05
2015-01-13
2015-04-30
2015-06-03

Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Tsushima (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)

Activity insuspended
sediments (Bq/kg)
3.51E+03
2.01E+04
2.16E+04
2.48E+04
2.27E+04
2.53E+04
1.77E+04
1.60E+04
2.06E+03
1.49E+03
2.31E+04
2.31E+4
1.86E+4
2.05E+4
3.15E+4
9.09E+3
1.03E+4
9.91E+3
9.24E+3
1.21E+4
1.08E+4
1.09E+4
5.69E+3
9.94E+3
1.51E+4
1.70E+4
8.76E+3
7.88E+3
1.16E+4
1.12E+4
3.09E+3
7.91E+3
4.72E+3
5.00E+3
7.03E+3
7.75E+3
7.95E+3
5.55E+04
6.55E+04
5.32E+04
4.06E+04
6.78E+04
8.48E+04
5.60E+04
5.11E+04
3.13E+04
4.05E+04
4.40E+04
3.14E+04
4.60E+04
2.78E+4
2.36E+4Standard
deviation
1.11E+03
6.82E+02
4.33E+02
5.78E+02
5.79E+02
5.44E+02
3.52E+02
4.31E+02
3.29E+02
2.09E+02
5.18E+02
3.69E+2
3.33E+2
1.96E+2
2.46E+2
6.50E+1
1.20E+2
1.82E+2
1.50E+2
5.76E+2
1.39E+2
4.22E+2
2.31E+2
3.41E+2
2.25E+2
2.57E+2
8.70E+1
1.31E+2
1.50E+2
9.09E+2
8.90E+1
6.10E+1
1.11E+2
5.60E+1
1.64E+2
7.10E+1
5.00E+2
1.04E+03
8.02E+02
8.80E+02
3.54E+02
1.38E+03
1.83E+03
5.58E+02
7.09E+02
6.44E+02
5.13E+02
1.21E+03
3.43E+02
1.40E+03
1.62E+2
2.92E+2

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

152.6

2566

79

Table II.1. (cont.)
Sampling
date

Site(river name)2015-08-03
2016-02-22
2016-04-08
2016-10-27
2016-12-20
2017-03-01
2017-07-10
2017-07-10
2017-12-11
2017-12-11
2018-05-01
2018-05-01
2018-07-02
2018-07-02
2018-10-26
2018-12-04
2019-04-23
2019-07-03
2019-11-18
2020-02-18
2020-05-13
2020-07-09
2020-10-15
2021-02-04
2012-12-17
2013-01-09
2013-01-21
2013-02-25
2013-09-11
2013-09-25
2013-10-29
2013-11-19
2014-01-15
2014-02-27
2014-08-08
2014-09-10
2014-10-22
2014-12-05
2015-01-13
2015-04-30
2015-06-03
2015-08-03
2015-09-02
2015-10-15
2016-02-22
2016-04-08
2016-06-10
2016-10-27
2016-12-20
2017-03-01
2017-05-15
2017-07-10

Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Ukedo (Ukedo)
Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)80

Activity insuspended
sediments (Bq/kg)
3.73E+4
3.07E+4
2.29E+4
1.84E+4
2.14E+4
1.84E+4
2.82E+4
2.41E+4
2.68E+4
2.70E+4
2.38E+4
1.93E+4
2.25E+4
2.13E+4
2.91E+4
2.10E+4
1.55E+4
1.38E+4
2.06E+4
1.04E+4
2.77E+3
4.78E+3
1.13E+4
5.15E+3
2.75E+04
2.03E+04
2.57E+04
2.13E+04
2.62E+04
2.05E+04
1.20E+04
1.09E+04
2.05E+04
3.13E+04
7.75E+03
8.10E+03
1.26E+04
1.07E+04
7.91E+03
1.14E+4
9.03E+3
9.07E+3
8.01E+3
6.73E+3
8.72E+3
6.42E+3
1.16E+4
2.63E+3
5.70E+3
4.34E+3
8.69E+3
9.12E+3Standard
deviation
2.01E+2
2.85E+2
5.21E+2
2.03E+2
3.36E+2
2.78E+2
2.34E+2
2.99E+2
1.45E+2
1.26E+2
1.58E+2
8.30E+1
1.48E+2
1.31E+2
1.60E+2
1.50E+2
3.51E+2
6.32E+2
1.01E+2
8.30E+1
2.90E+1
3.07E+2
1.44E+2
1.12E+2
3.63E+02
4.57E+02
3.63E+02
3.58E+02
9.11E+02
7.10E+02
2.95E+02
2.09E+02
2.00E+02
7.81E+02
1.62E+02
1.94E+02
2.57E+02
2.49E+02
1.04E+02
1.60E+2
2.71E+2
1.34E+2
1.12E+2
6.80E+1
1.36E+2
3.07E+2
1.62E+2
2.50E+1
1.73E+2
1.87E+2
3.10E+2
2.22E+2

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

263.7

726.0

Table II.1. (cont.)
Sampling
date

Site(river name)2017-09-05
2017-12-11
2018-05-28
2018-07-02
2018-09-20
2018-10-12
2018-12-04
2019-04-23
2019-07-03
2020-07-09
2020-10-15
2021-02-04
2012-12-06
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-18
2013-05-21
2013-06-18
2013-07-25
2013-08-08
2013-08-22
2013-09-11
2013-09-26
2013-10-30
2013-11-20
2013-12-23
2014-01-17
2014-02-26
2014-08-05
2014-09-09
2014-10-21
2014-12-04
2015-01-14
2015-04-17
2015-06-17
2015-07-27
2015-09-02
2016-02-22
2016-05-09
2016-06-21
2016-10-27
2016-12-20
2017-03-02
2017-05-09
2017-07-07
2017-09-06
2017-12-04
2018-05-31
2018-07-02
2018-10-11

Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Takase (Takase)Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)

Activity insuspended
sediments (Bq/kg)
1.44E+4
2.54E+3
3.55E+3
6.55E+3
2.77E+3
3.96E+4
5.19E+3
5.41E+3
4.92E+3
6.41E+3
2.87E+3
2.44E+3
3.13E+04
1.32E+04
2.75E+04
2.43E+04
1.81E+04
2.74E+04
3.18E+04
1.61E+04
2.92E+04
3.61E+04
1.68E+04
3.51E+04
3.12E+04
2.66E+04
2.93E+04
2.13E+03
2.72E+04
2.00E+04
2.08E+03
1.87E+04
1.84E+04
1.86E+04
1.84E+04
1.62E+4
1.45E+4
1.37E+4
1.58E+4
7.46E+3
5.87E+3
6.29E+3
4.45E+3
4.46E+3
2.73E+3
4.67E+3
5.06E+3
7.77E+3
6.33E+3
6.36E+3
5.82E+3
4.11E+3Standard
deviation
2.33E+2
2.50E+1
5.50E+1
2.23E+2
2.30E+1
1.36E+2
4.98E+2
7.61E+2
1.19E+2
1.18E+2
3.20E+1
6.30E+1
1.10E+03
1.31E+03
5.15E+02
5.06E+02
5.83E+02
3.60E+02
7.79E+02
2.08E+02
2.67E+02
7.71E+02
1.05E+02
4.78E+02
1.10E+03
3.25E+02
4.59E+02
5.19E+02
6.05E+02
3.86E+02
3.58E+02
4.03E+02
3.19E+02
2.79E+02
4.91E+02
1.72E+2
2.59E+2
1.94E+2
1.68E+2
1.19E+2
9.00E+1
3.49E+2
4.40E+1
7.70E+1
1.43E+2
1.17E+2
7.70E+1
4.90E+1
3.30E+1
6.60E+1
4.20E+1
3.00E+1

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

200.3

963.7

81

Table II.1. (cont.)
Sampling
date

Site(river name)2018-12-04
2019-04-25
2019-08-05
2020-03-06
2020-05-14
2021-02-02
2012-12-18
2013-01-10
2013-01-22
2013-02-26
2013-04-17
2013-05-20
2013-06-17
2013-07-25
2013-08-08
2013-08-22
2013-09-12
2013-09-26
2013-10-30
2013-11-20
2013-12-24
2014-01-16
2014-02-25
2014-08-06
2014-09-08
2014-10-20
2014-12-03
2015-01-14
2015-05-01
2015-05-28
2015-07-23
2015-08-27
2015-10-06
2015-12-04
2016-01-28
2016-02-22
2016-04-13
2016-06-10
2016-08-02
2016-09-29
2016-12-20
2017-03-01
2017-05-09
2017-07-10
2017-09-06
2017-12-12
2018-05-31
2018-07-04
2018-10-17
2018-12-03
2019-04-25
2019-08-06

Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Haramachi (Niida)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)

82

Activity insuspended
sediments (Bq/kg)
6.37E+3
6.23E+3
7.32E+3
1.67E+3
7.84E+2
3.29E+3
9.88E+02
2.19E+03
1.39E+03
1.99E+03
1.74E+02
1.26E+03
1.21E+03
1.66E+03
1.04E+03
1.40E+03
1.52E+03
4.28E+02
4.77E+02
1.14E+03
3.06E+03
1.59E+03
3.98E+02
4.13E+02
8.96E+02
6.48E+02
6.31E+02
7.23E+02
6.93E+2
9.09E+2
4.36E+2
6.71E+2
2.62E+2
9.94E+2
9.02E+2
2.78E+2
1.25E+3
6.34E+2
8.60E+2
5.32E+2
1.16E+3
4.19E+2
4.04E+2
5.76E+2
7.27E+2
7.41E+2
1.33E+2
5.23E+2
5.08E+2
8.74E+2
2.40E+2
2.64E+2Standard
deviation
5.59E+2
1.48E+2
1.21E+2
1.10E+1
1.00E+1
4.00E+1
3.80E+01
4.00E+01
4.20E+01
7.40E+01
7.90E+01
1.90E+01
2.20E+01
4.60E+01
3.70E+01
4.90E+01
5.90E+01
1.30E+01
1.70E+01
4.10E+01
4.90E+01

1.70E+01
3.10E+01
1.70E+01
8.00E+00
2.80E+01
4.00E+1
5.40E+1
2.40E+1
5.10E+1
1.10E+1
4.00E+1
4.10E+1
4.70E+1
1.00E+2
5.30E+1
3.10E+1
1.00E+1
5.10E+1
6.80E+1
2.70E+1
5.00E+1
1.60E+1
4.30E+1
9.00E+0
3.60E+1
2.70E+1
1.03E+2
2.00E+1
2.10E+1

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

242.6

52.6

Table II.1. (cont.)
Sampling
date

Site(river name)2019-11-15
2020-02-26
2020-05-12
2020-07-06
2020-11-11
2021-02-01

Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)
Akanuma (Otakine)

Activity insuspended
sediments (Bq/kg)
4.15E+2
2.12E+2
1.79E+2
6.07E+2
2.69E+2
7.70E+1

Standard
deviation

Catchment area
(km²)

Mean depositionin the catchment(kBq/m²)

1.70E+1
8.00E+0
4.00E+0
3.30E+1
1.50E+1
1.40E+1

83

APPENDIX III. FLUX OF CAESIUM-137 IN RIVERS OF THE FUKUSHIMAPREFECTURE
Table III.1: Monthly flux of particulate 137Cs (Bq) in rivers of the Fukushima Prefecture [15].
For the months/sites with green or brown values, data on water level and/or turbidity data were
not available. For these cases, the flux of particulate 137Cs was determined as described inRef. [15]. The data are the basis for the preparation of Figure 12.
Sampling month
06/201107/201108/2011
09/2011
10/2011
11/2011
12/201101/201202/201203/201204/201205/201206/201207/201208/201209/2012
10/2012
11/2012
12/201201/201302/201303/201304/201305/201306/201307/201308/2013
09/2013
10/2013
11/2013
12/201301/201402/201403/201404/201405/201406/201407/201408/201409/2014
10/2014
11/2014
12/201401/2015
02/2015
03/2015
04/2015
05/2015
06/2015
07/2015
08/2015
Total
06/11- 08/15

Monthly flux of particulate Cs-137 in rivers (Bq)
Mizusakai
1.31E+08
1.56E+09
1.55E+09
2.88E+09
2.49E+08
8.58E+07
9.49E+07
4.74E+07
1.10E+08
3.60E+08
3.96E+08
3.42E+08
3.19E+08
3.39E+08
1.42E+07
1.52E+08
5.38E+07
1.22E+07
4.63E+07
3.26E+06
1.78E+07
3.08E+08
4.06E+08
2.02E+07
1.50E+08
1.09E+09
1.51E+08
9.85E+07
5.03E+08
9.08E+07
3.92E+07
1.69E+07
2.41E+07
1.56E+09
9.03E+08
1.32E+08
3.75E+09
2.36E+09
1.02E+09
1.06E+08
9.96E+07
3.48E+07
4.52E+07
1.59E+07
1.65E+07
5.97E+07
3.51E+07
1.29E+07
2.12E+07
2.76E+07
1.62E+07

Kuchibuto (up)9.69E+08
7.75E+09
5.07E+09
2.26E+10
1.13E+09
1.69E+08
2.32E+08
6.34E+07
4.27E+08
1.03E+09
1.83E+09
5.82E+08
2.11E+09
2.14E+09
9.42E+08
1.52E+09
7.26E+08
8.57E+08
2.16E+09
1.66E+09
9.09E+08
4.06E+08
1.97E+09
1.14E+09
8.74E+08
2.47E+09
1.90E+09
2.29E+09
3.27E+09
1.76E+09
1.66E+09
1.40E+09
1.70E+09
4.68E+09
3.59E+09
1.96E+09
3.59E+09
3.32E+09
6.99E+09
1.44E+09
1.87E+09
9.48E+08
1.30E+09
5.51E+08
4.15E+08
1.01E+09
6.97E+08
8.92E+08
1.60E+09
2.64E+09
5.60E+08

Kuchibuto (mid)1.11E+09
1.66E+10
8.45E+09
5.53E+10
3.65E+09
5.52E+08
6.14E+08
6.25E+07
5.52E+08
3.47E+09
3.53E+09
2.30E+09
3.89E+09
4.10E+09
4.34E+08
1.08E+09
1.53E+09
8.43E+08
1.00E+09
7.72E+08
3.55E+08
1.35E+08
1.46E+09
1.76E+08
1.59E+09
5.20E+09
7.23E+09
8.17E+09
9.07E+09
1.65E+09
1.16E+09
9.84E+08
9.24E+08
6.58E+09
4.61E+09
8.66E+08
8.29E+09
9.98E+09
1.12E+10
1.20E+09
5.37E+09
1.19E+09
2.11E+09
1.24E+09
1.79E+09
7.74E+09
4.47E+09
1.31E+09
3.58E+09
9.09E+09
5.05E+09

Kuchibuto (down)
5.10E+09
1.00E+11
2.81E+10
8.17E+10
4.10E+09
7.88E+08
5.34E+08
2.94E+08
1.93E+09
1.07E+10
1.27E+10
4.77E+09
9.19E+09
9.47E+09
2.24E+09
1.27E+10
2.94E+09
1.56E+09
1.78E+09
4.13E+08
5.51E+08
9.43E+08
5.92E+09
2.39E+08
3.13E+09
9.99E+09
8.15E+09
5.40E+09
8.77E+09
1.14E+09
8.26E+08
5.22E+08
7.70E+08
3.02E+10
1.21E+10
2.60E+09
9.99E+09
2.90E+10
1.60E+10
3.53E+09
9.65E+09
2.02E+09
4.42E+09
3.14E+09
2.89E+09
1.19E+10
8.88E+09
3.40E+09
4.87E+09
1.08E+10
6.92E+09

Fushiguro
1.29E+12
2.09E+12
3.69E+11
1.36E+12
9.72E+10
5.71E+10
5.43E+10
7.46E+10
1.27E+11
5.04E+11
2.12E+11
8.83E+11
1.90E+11
1.60E+11
2.93E+10
5.40E+10
1.03E+11
2.88E+10
2.81E+10
7.50E+10
1.59E+11
1.04E+11
1.40E+11
2.26E+10
3.86E+10
3.24E+11
2.64E+11
4.08E+11
2.12E+11
3.92E+10
5.06E+10
3.28E+10
4.62E+10
1.80E+11
9.44E+10
3.75E+10
9.72E+10
2.27E+11
1.17E+11
1.85E+10
1.96E+11
3.30E+10
3.27E+10
4.73E+10
4.95E+10
1.55E+11
1.25E+11
2.82E+10
6.49E+10
1.95E+11
3.33E+10

Iwanuma
1.05E+12
1.95E+12
4.25E+11
3.41E+12
1.81E+11
9.49E+10
4.00E+10
5.95E+10
5.75E+10
2.21E+11
6.45E+10
7.28E+11
2.11E+11
1.84E+11
6.38E+10
6.09E+10
8.86E+10
7.54E+10
6.05E+10
6.74E+10
5.49E+10
4.64E+10
5.54E+10
3.29E+10
3.87E+10
5.72E+11
4.99E+11
3.15E+11
2.67E+11
2.04E+10
2.38E+10
1.47E+10
1.76E+10
6.06E+10
9.68E+10
2.50E+10
1.40E+11
2.24E+11
5.02E+10
3.28E+10
2.13E+11
4.69E+10
5.21E+10
3.51E+10
2.94E+10
1.03E+11
7.68E+10
4.06E+10
3.45E+10
1.03E+11
4.42E+10

2.19E+10

1.14E+11

2.34E+11

5.10E+11

1.13E+13

1.24E+13

85

Table III.1. (cont.)
Samplingmonth
10/2012
11/2012
12/201201/201302/201303/201304/201305/201306/201307/201308/2013
09/2013
10/2013
11/2013
12/201301/201402/201403/201404/201405/201406/201407/201408/201409/2014
10/2014
11/2014
12/201401/2015
02/2015
03/2015
04/2015
05/2015
06/2015
07/2015
08/2015
Total
10/12-08/15

86Monthly flux of particulate Cs-137 in rivers (Bq)Mano
2.74E+08
8.57E+08
7.14E+08
3.54E+08
5.13E+08
1.14E+09
2.58E+09
5.69E+08
6.72E+08
1.14E+09
9.49E+08
9.46E+08
8.94E+08
3.43E+08
2.47E+08
1.48E+08
3.35E+08
1.27E+09
1.20E+09
2.21E+09
3.63E+09
7.43E+09
1.03E+09
3.28E+08
1.30E+09
1.44E+08
3.14E+08
4.31E+08
6.33E+08
1.16E+09
1.09E+09
4.22E+08
2.98E+08
2.75E+08
7.30E+07

Ojimadazeki
6.14E+08
1.15E+09
1.25E+09
1.21E+09
1.04E+09
1.09E+09
1.02E+09
1.09E+09
1.07E+09
2.00E+08
7.26E+08
4.85E+09
3.63E+09
3.09E+08
2.58E+08
9.66E+07
5.24E+08
3.16E+09
2.42E+09
8.46E+08
5.36E+09
4.41E+09
1.49E+09
2.78E+08
3.19E+09
1.41E+08
9.90E+07
4.26E+07
1.01E+08
2.69E+09
9.07E+08
6.78E+08
5.87E+08
8.82E+08
1.11E+09

Matsubara
5.42E+08
3.60E+08
1.80E+08
1.25E+08
2.14E+08
4.77E+08
1.63E+09
3.55E+08
8.92E+08
1.95E+09
4.53E+08
2.17E+09
9.83E+08
5.92E+07
4.51E+08
5.25E+08
4.38E+08
3.75E+08
1.65E+09
2.09E+08
6.13E+08
6.43E+08
5.96E+08
4.90E+08
8.86E+08
8.28E+08
4.34E+08
5.87E+08
5.89E+08
2.49E+08
1.35E+08
1.64E+08
2.20E+08
3.75E+08
8.16E+08

Onahama
4.82E+07
3.93E+07
4.05E+07
1.75E+07
1.27E+07
1.33E+07
1.17E+09
2.29E+07
2.59E+07
5.69E+07
5.05E+07
4.79E+08
2.85E+09
1.24E+07
1.10E+07
5.10E+06
1.25E+08
8.27E+07
7.60E+08
1.33E+08
1.13E+09
6.76E+08
1.93E+08
7.01E+07
2.05E+09
6.11E+07
5.61E+07
9.07E+07
9.75E+07
5.10E+08
1.23E+08
8.73E+07
7.34E+07
1.68E+08
1.63E+08

Tsukidate
1.82E+08
1.34E+09
3.39E+08
1.46E+08
5.50E+08
7.32E+06
2.18E+09
1.44E+08
3.95E+08
3.20E+09
2.42E+09
5.44E+09
1.83E+09
6.47E+08
5.48E+08
4.24E+08
8.12E+08
2.26E+09
1.12E+09
8.57E+09
8.21E+09
6.29E+09
2.05E+10
5.79E+08
2.46E+09
1.13E+09
1.00E+09
4.93E+08
5.63E+07
3.92E+08
2.19E+08
2.50E+07
2.99E+07
7.47E+07
1.05E+08

Nihomatsu
4.46E+09
4.31E+09
1.51E+10
7.90E+09
2.61E+09
1.94E+09
8.49E+10
4.88E+09
3.15E+10
7.10E+10
2.27E+10
3.09E+10
8.45E+09
1.56E+09
3.21E+09
2.65E+08
1.33E+09
2.02E+10
1.19E+10
4.08E+09
1.95E+10
5.37E+10
2.74E+10
1.29E+10
6.94E+10
4.16E+09
2.78E+10
1.09E+10
4.76E+09
1.17E+10
9.60E+09
1.29E+09
3.25E+09
1.54E+10
4.37E+09

Nishikawa
8.77E+08
7.12E+08
4.56E+08
2.11E+08
5.76E+08
9.55E+07
3.11E+09
4.79E+08
8.91E+08
1.02E+10
1.54E+10
6.14E+09
2.19E+10
2.85E+08
2.32E+08
7.21E+07
1.52E+08
4.44E+09
1.66E+09
2.61E+08
4.21E+09
7.48E+09
4.35E+09
6.53E+08
4.44E+09
1.32E+09
1.97E+09
1.37E+09
1.19E+09
4.75E+09
3.11E+09
7.64E+08
1.33E+09
4.74E+09
3.73E+09

Kitamachi
2.84E+09
3.08E+09
2.88E+09
7.25E+07
2.57E+08
3.98E+08
1.04E+10
1.15E+09
2.39E+09
3.98E+08
3.73E+09
2.48E+09
5.57E+09
5.45E+08
5.34E+08
4.66E+08
3.56E+09
1.66E+09
4.86E+09
4.21E+09
3.82E+09
7.72E+09
5.38E+09
6.56E+08
3.85E+09
1.37E+08
1.27E+08
6.28E+07
4.16E+07
4.43E+08
2.72E+08
1.31E+08
4.31E+08
6.98E+08
2.05E+08

Kawamata
1.20E+08
3.85E+08
8.13E+08
2.45E+08
8.49E+08
7.67E+07
7.79E+08
2.49E+08
5.98E+08
8.25E+09
2.09E+09
1.97E+09
2.03E+09
2.32E+08
3.31E+08
7.80E+07
1.31E+08
5.48E+08
8.05E+08
5.16E+07
4.51E+08
9.59E+08
6.00E+08
1.17E+08
4.61E+08
1.59E+08
1.54E+08
1.16E+08
8.55E+07
3.06E+08
2.19E+08
7.60E+07
6.52E+07
9.95E+07
1.02E+08

Senoue7.36E+08
1.13E+09
3.46E+09
4.16E+08
7.20E+08
2.62E+09
1.82E+09
1.32E+09
5.77E+08
8.93E+09
2.91E+09
5.42E+09
3.96E+09
1.43E+09
3.29E+09
2.78E+09
1.12E+09
2.77E+09
2.01E+09
9.35E+08
3.01E+09
6.51E+09
1.93E+09
8.53E+08
1.50E+09
7.90E+08
1.26E+09
1.05E+09
9.11E+08
2.72E+09
2.78E+09
1.32E+09
1.16E+09
1.83E+09
1.81E+09

Yagita
4.77E+08
4.02E+08
3.53E+08
7.76E+07
1.55E+08
1.35E+09
6.35E+09
4.40E+08
9.78E+08
9.73E+09
3.31E+09
3.03E+09
3.49E+09
2.28E+08
3.01E+08
1.31E+08
2.28E+08
8.91E+08
1.51E+09
5.48E+08
5.10E+09
9.39E+09
6.25E+09
5.12E+09
1.28E+10
1.69E+09
9.08E+08
1.70E+09
2.50E+09
2.68E+09
2.99E+09
4.58E+09
2.37E+09
4.48E+09
4.83E+09

3.59E+10

4.85E+10

2.17E+10

1.15E+10

7.42E+10

6.09E+11

1.14E+11

7.54E+10

2.46E+10

7.78E+10

1.01E+11

Table III.1 (cont.)
Samplingmonth
10/2012
11/2012
12/201201/201302/201303/201304/201305/201306/201307/201308/2013
09/2013
10/2013
11/2013
12/201301/201402/201403/201404/201405/201406/201407/201408/201409/2014
10/2014
11/2014
12/201401/2015
02/2015
03/2015
04/2015
05/2015
06/2015
07/2015
08/2015
Total
10/12-08/15

Monthly flux of particulate Cs-137 in rivers (Bq)
Senoue7.36E+08
1.13E+09
3.46E+09
4.16E+08
7.20E+08
2.62E+09
1.82E+09
1.32E+09
5.77E+08
8.93E+09
2.91E+09
5.42E+09
3.96E+09
1.43E+09
3.29E+09
2.78E+09
1.12E+09
2.77E+09
2.01E+09
9.35E+08
3.01E+09
6.51E+09
1.93E+09
8.53E+08
1.50E+09
7.90E+08
1.26E+09
1.05E+09
9.11E+08
2.72E+09
2.78E+09
1.32E+09
1.16E+09
1.83E+09
1.81E+09

Yagita
4.77E+08
4.02E+08
3.53E+08
7.76E+07
1.55E+08
1.35E+09
6.35E+09
4.40E+08
9.78E+08
9.73E+09
3.31E+09
3.03E+09
3.49E+09
2.28E+08
3.01E+08
1.31E+08
2.28E+08
8.91E+08
1.51E+09
5.48E+08
5.10E+09
9.39E+09
6.25E+09
5.12E+09
1.28E+10
1.69E+09
9.08E+08
1.70E+09
2.50E+09
2.68E+09
2.99E+09
4.58E+09
2.37E+09
4.48E+09
4.83E+09

Kuroiwa
3.91E+10
2.89E+10
2.25E+10
2.81E+10
4.43E+10
1.99E+10
9.07E+10
1.48E+10
2.35E+10
7.43E+11
4.74E+11
1.65E+11
1.53E+11
5.23E+09
1.61E+10
3.40E+09
9.67E+09
6.39E+10
5.77E+10
1.26E+10
9.41E+10
3.01E+11
1.32E+11
3.10E+10
2.39E+11
1.31E+10
8.87E+09
4.50E+09
4.62E+09
5.44E+10
4.07E+10
1.68E+10
3.33E+10
6.12E+10
6.69E+09

Tomita
6.70E+09
6.10E+09
2.11E+09
1.57E+09
1.19E+10
1.69E+09
3.08E+09
2.65E+09
6.43E+09
8.79E+10
4.90E+09
1.62E+10
7.08E+10
1.73E+09
2.35E+09
8.97E+08
1.40E+09
9.60E+09
3.20E+09
5.37E+09
1.09E+10
1.67E+10
2.33E+09
6.55E+08
1.06E+10
7.43E+08
6.37E+08
4.13E+08
3.12E+08
5.14E+09
3.79E+09
8.86E+08
2.23E+09
3.21E+09
2.71E+09

Ota
1.82E+08
4.88E+08
3.77E+08
3.78E+08
2.52E+08
2.94E+08
4.03E+08
1.92E+08
3.74E+08
3.79E+08
6.99E+08
4.73E+08
6.52E+08
9.55E+07
3.57E+07
2.77E+07
2.89E+07
2.64E+08
1.76E+09
2.23E+08
9.20E+08
6.84E+08
1.89E+09
1.51E+09
7.99E+09
7.09E+08
6.36E+08
4.78E+08
3.17E+08
6.12E+08
5.41E+08
4.78E+08
2.92E+08
8.07E+08
4.27E+08

Odaka
8.09E+07
1.36E+08
7.92E+07
4.59E+07
3.66E+07
4.52E+07
2.01E+08
5.76E+06
1.97E+08
1.80E+08
6.97E+07
1.52E+09
3.01E+09
1.53E+08
1.02E+08
1.44E+08
3.42E+08
3.41E+08
6.43E+08
3.25E+08
1.84E+09
1.52E+09
2.57E+09
8.71E+08
6.32E+09
6.50E+08
2.99E+08
3.36E+08
4.57E+08
3.47E+09
6.90E+08
4.12E+08
5.55E+08
6.88E+08
5.80E+08

Asami
1.68E+06
6.20E+06
1.72E+07
8.02E+06
6.23E+06
1.46E+06
5.37E+07
3.87E+06
6.20E+06
1.11E+07
7.88E+06
4.03E+07
1.01E+08
2.33E+07
2.94E+07
7.66E+06
3.44E+07
9.22E+07
2.63E+08
1.70E+08
3.57E+08
2.40E+08
5.32E+08
2.50E+08
1.09E+09
9.58E+07
1.21E+08
6.38E+07
6.26E+07
1.67E+08
3.98E+07
4.18E+08
6.60E+07
3.07E+08
1.35E+08

Tsushima
1.26E+08
2.71E+08
2.41E+08
3.86E+08
1.62E+08
2.23E+08
6.71E+08
1.58E+08
1.58E+08
2.55E+08
7.02E+08
1.52E+09
2.10E+09
2.51E+08
4.52E+08
3.17E+08
3.38E+08
1.34E+09
1.16E+09
5.23E+08
4.49E+09
2.15E+08
1.46E+09
5.29E+08
3.78E+09
3.88E+08
4.31E+08
1.10E+08
9.99E+07
8.92E+08
5.28E+08
1.30E+08
6.45E+07
2.35E+08
1.68E+08

Ukedo
2.49E+09
4.47E+09
4.88E+09
3.33E+09
2.39E+09
6.44E+09
1.61E+10
2.55E+09
2.02E+09
1.12E+10
3.63E+10
2.00E+11
3.98E+10
4.32E+09
5.13E+09
1.78E+09
4.24E+09
4.98E+10
6.18E+10
5.14E+09
8.99E+10
8.22E+10
4.05E+10
3.01E+10
6.85E+10
1.16E+10
1.38E+10
7.44E+09
7.79E+09
2.59E+10
1.26E+10
5.71E+09
1.10E+10
1.90E+10
9.08E+09

Takase
4.84E+07
3.80E+08
4.58E+08
1.60E+08
7.57E+07
2.41E+08
7.06E+09
4.59E+08
2.04E+09
6.53E+09
2.35E+09
1.61E+10
2.81E+11
2.21E+09
3.65E+08
6.04E+07
2.58E+08
4.83E+10
1.09E+11
4.06E+08
8.00E+10
3.61E+10
1.76E+10
5.92E+09
7.64E+10
3.07E+09
2.08E+09
9.94E+08
1.20E+09
2.07E+10
9.75E+09
2.99E+09
2.11E+09
6.45E+10
3.13E+09

Haramachi
1.09E+09
1.74E+09
1.33E+09
7.39E+08
7.77E+08
1.24E+09
8.99E+09
7.42E+08
1.86E+09
1.14E+10
9.86E+09
5.73E+10
8.51E+10
4.74E+09
2.23E+09
1.51E+09
3.29E+09
4.31E+10
3.14E+10
1.06E+10
6.49E+10
3.90E+10
5.01E+10
5.74E+09
2.99E+10
2.26E+09
1.60E+09
1.17E+09
1.36E+09
1.31E+10
5.17E+09
6.98E+08
1.30E+09
3.11E+09
6.28E+09

Akanuma
2.80E+08
2.60E+08
1.67E+08
1.25E+08
1.02E+08
1.14E+08
4.46E+08
1.50E+08
1.30E+08
1.10E+09
3.00E+08
6.21E+08
2.46E+08
2.01E+07
2.14E+08
9.78E+07
2.95E+07
4.25E+08
5.72E+08
4.43E+08
3.49E+08
7.77E+08
7.56E+08
4.05E+08
1.29E+09
2.29E+08
2.81E+08
2.38E+08
2.19E+08
1.05E+09
8.30E+08
5.33E+08
3.23E+08
1.32E+09
3.94E+08

7.78E+10

1.01E+11

3.06E+12

3.08E+11

2.59E+10

2.89E+10

4.83E+09

2.49E+10

8.99E+11

8.03E+11

5.05E+11

1.48E+1087

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CONTRIBUTIONS TO DRAFTING AND REVIEW

Arai, H.

Kyoto University, Japan

Brown, J.

International Atomic Energy Agency, Austria

Halsall, C.

International Atomic Energy Agency, Austria

Laptev, G.

Ukrainian Hydrometeorological Institute, Ukraine

Nasu, K.

Fukushima Prefecture, Japan

Pröhl, G.

Consultant, Germany

Saito, H.

International Atomic Energy Agency, Austria

Takeuchi, Y.

Fukushima Prefecture, Japan

Taniguchi, K.

National Institute of Technology, Tsuyama College, Japan

Yamasaki, T.

The University of Tokyo, Japan

Yankovich, T. L.

International Atomic Energy Agency, Austria

96