Yuichi Onda, Keisuke Taniguchi, Hiroaki Kato, Kazuya

Yoshimura, Yoshifumi Wakiyama, Sho Iwagami, Maki

Tsujimura, Aya Sakaguchi

Center for Research in Isotopes and Environmental Dynamics

University of Tsukuba

Masatoshi Yamamoto LLRL, Kanazawa University

Time changes in radiocesium

concentration in aquatic systems

affected by the Fukushima Daiichi

NPP accident

,

Mapping of radio-Cs

2 km mesh in Fukushima pref.

・Sampling participants: more than 1000 people

・Sampling points: about 2200

・Sample numbers: about 11000

・Sampling area: in 80 km from Fukushima-daiich NPP

・Cooperative institutes and companies:

94 universities (hospitals), 14 companies

・ Analytical institutes: 20

・Sampling :

First campaign : 6th/June – 14th/June

Second campaign : 27th/June – 8th/July

Thank you for the IAEA’ s support!(protocol, standard material etc)

Time Change of Cs-137 concentration in water in Ukraine C

s-137 c

on

cen

trati

on

in

wate

r

[Bq

/m3]

k1

k2

k3

after Smith et al, (2005 )

)()()()()( 321 tktktk

cR eeeDtC

First flush

Fixation?

Downward migration?

Fukushima 2011 2014

June 2011- 2014 (funded by MEXT, NRA)

Yamakiya area

Pasture A plot

Cropland B1, B2

plot Cropland A1, A2

plot

Paddy field (scraped, control)

Kotaishi catchment

Iboishi

catchment

Pasture B plot

Ishidaira

Cathment Pasture C plot

Yamakiya Study site Cs transfer from forested area

Sediment and Cs yield from various land

use

Young cedar

Mature cedar

Broadleaf

Cs transfer in forest

Young cedar plot

河川

都市域

水田

草地

畑地

森林

流域界

Forest

Cropland

Grassland

Paddy

field

City

River

Kuchibuto

upstream

Mizusakai

River monitoring sites

Bare land Cultivated (gentle)

Forest (young ceder)

Soil Erosion Plots

Grass land Cultivated (Steep)

Pasture A Pasture B

Parshall flume

and water gage

↑turbidimeter・

SS sampler

Striped surface soil

(5-10cm)↓

Non-striped

surface soil

Migration with cultivation Migration of radionuclides from paddy field to river (and plant) by rice cultivation.

Migration form soil to rice plant

SS sampler

Observation of suspended sediment discharge from paddy field by puddling

11

Young cedar Mature cedar Broadleaf

(Beech and Red pine)

Experimental site

Mature cedar

1200/ha

Young cedar

3300/ha Broadleaf

2500/ha

Stemflow collector

Throughfall collector

Filtering water by 100μm stainless mesh.

Water samples Litter samples

Leaves, twig, branch, bark were manually separated.

(a) Mature cedar

Cumulative Cs-137 deposition (Bq m-2) onto forest floor

TF

LF

SF

TF

LF

SF

TF

LF

SF

(b) Young cedar (c) Broad-leaved Jan. 2012

Oct. 2011

Apr. 2012

Aug. 2012

Nov. 2012

Jan. 2012

Oct. 2011

Apr. 2012

Aug. 2012

Nov. 2012

Jan. 2012

Oct. 2011

Apr. 2012

Aug. 2012

Nov. 2012

Throughfall + Litterfall input

200 days after the NPP accident JER (under review)

Time series of dissolved 137Cs concentration in stream water at Iboishiyama and time series of dissolved 137Cs

concentration in groundwater at Iboishiyama with exponential approximate line.

Stream water

-30 m GW

-5 m GW

-15 m GW

C(t) = 1.181e-0.011t+0.114e-0.001t

C(t) = 0.012e-0.004t

C(t) = 0.023e-0.003t

C(t) = 0.002e-0.0004t

200 days!

Throughfall!

JER (in press)

Headwater catchment

Groundwater

Bare land Cultivated (gentle)

Forest (young ceder)

Soil Erosion Plots

Grass land Cultivated (Steep)

Pasture A Pasture B

Temporal change in normalized cesium-137 concentration in sediment discharge from each plot. Each point

Scuncultivated(t) = 0.0619 exp(-0.196t) Sccultivated = 0.0137 （Averaged value of the 2 plots (A2,B2)

Scgrassland = 0.0134 （average value of grassland A,B,C)

Normalized Cs-137 cocentration (Sc): 137Cs concentration per unit deposition density

0.001

0.01

0.1

1

0 1 2 3 4

No

rma

liz

ed

co

ce

ntr

ati

on

Sc

(B

q k

g-1

)/(B

q m

-2)

Time after the FDNPP accident (year)

福島県内固定観測点によるSc

代掻き時調査に基づくSc

Scpaddy(t) = 1.62e -10.1t + 0.145e-0.958t Scforest(t) = 0.074e -0.327 t

Normalized Cs-137 Concentration (Sc)

Paddy field Sc(t) Forest catchments Sc(t)

Experimental paddy

Fukushima paddling data Ishidaira site

18

Radionuclide migration to rivers and ocean (initial 6 sites)

19

From 10 August 2011 to 11 May 2012 The total flux

of radiocesium into the Pacific Ocean estimated

was corresponding to 1.13%of the total estimated

radiocesium fallout over the basin catchment.

River monitoring sites

1. Longer-term Abukuma sites (n = 6):

– Established from June 2011

2. New sites (n = 24):

– Abukuma Basin and small coastal catchments

– Established in October-December 2012

• Catchment areas range from 7.6 – 5,170 km2

• Average inventories based on MEXT

• Cs-137: 19-2380 kBq m-2

Kuchibuto upstream

Kuchibuto down

Iwanuma

Fushiguro

Mizusakai Kuchibuto Middle

河川

都市域

水田

草地

畑地

森林

流域界

Forest

Cropland

Grassland

Paddy field

City

River

Landuses in Abukuma catchments and 6 long-term sites

Time change of suspended sediment concentration in 6 long-term sites

1000

10000

100000

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

Susp

en

de

d s

ed

ime

nt

Cs-

13

7 c

on

cen

trat

ion

[B

q/k

g]

Year after the accident

水境川

口太川上流

口太川中流

口太川下流

伏黒

岩沼

tributary

mainstream

Abukuma main

stream

Kuchibuto

river(tributary)

Mizusakai Kuchibuto upstream Kuchibuto middle stream Kuchibuto Downstream Fukushiro (abukuma) Iwanuma (abukuma)

upstream

downstream

forest

Paddy field Urban

Time change of Suspended sediment Cs-137 concentration for 30 sites

0.001

0.01

0.1

1

0 0.5 1 1.5 2 2.5 3 3.5 4

Abukuma mainstream

0.001

0.01

0.1

1

0 0.5 1 1.5 2 2.5 3 3.5 4

Coastal catchment

0.001

0.01

0.1

1

0 0.5 1 1.5 2 2.5 3 3.5 4

Abukuma East Tributaries

No

rmar

ized

Cs-

13

7 C

on

cen

trat

ion

[B

q k

g-1

/B

q m

-2]

0.001

0.01

0.1

1

0 0.5 1 1.5 2 2.5 3 3.5 4

Abukuma West tributaries

Years after Fukushima NPP accidents

USLE-based soil erosion calculation (25m-grid)

NDVI高 : 8421

低 : 20

0̄ 10 205km

土地利用

水田

畑（耕作）

畑（ 未耕作）

草地

裸地

常緑樹針葉樹

常緑針葉樹（ マツ）

常緑広葉樹

落葉広葉樹

落葉針葉樹

都市

住宅

水域

湿原

そのほか

0̄ 10 205km

傾斜 (度)

40

0

0̄ 10 205km

(a) (b)

(c) (d)

Slope(S)

Vegetation factor （C）

Landuse

K factor

Calculation: 1 month step Input parameters ; Rainfall (Thiessen-based), Sc (t) of each land use :paddy:using the monthly discharge data Wakahara et al. 2014)

(a)平成23年3月11日～10月31日

kBq/m2

- 0.1

0.1 - 0.5

0.5 - 1

1 - 5

5 -10

10 -

¯0 10 205

km

kBq/m2

- 0.1

0.1 - 0.5

0.5 - 1

1 - 5

5 -10

10 -

¯0 10 205

km

kBq/m2

- 0.1

0.1 - 0.5

0.5 - 1

1 - 5

5 -10

10 -

¯0 10 205

km

(b)平成23年11月1日～平成24年10月31日

(c)平成24年11月1日～平成25年10月31日

Calculated Cs-137 migration

Calculation has been conducted 1 month step Input parameter ;Rainfall (Thiessen-based), Sc (t) of each land use :paddy:using the monthly discharge data by Wakahara et al. 2014)

a) Mar.31, 2011-Oct.31, 2011

b) Nov. 1, 2011-Oct.31, 2012

b) Nov. 1, 2012-Oct.31, 2013

Sediement source estimates by USLE-based model

No

rmal

ized

Cs-

13

7C

oce

ntr

atio

n (

Bq

/kg)

/(B

q/m

2)

Years after FDNPP accident

Mizusakai Kuchibuto upstream

Kuchibuto Middle stream

Kuchibuto downstream

Fushiguro (mainstream)

Iwanuma (mainstream)

Time Changes of the Model calculation and measured value for 6 long-term monitoring sites

measured

calculated

measured

calculated

measured

calculated

measured

calculated

measured

calculated

measured

calculated

Conclusion

Based on intensive field monitoring from June 2011-

present reveal that the time change of Cs-137 differ

between land uses.

Downstream Suspended sediment concentration

differs between places in by 30 locations of river

monitoring data.

For accurate modelling after Nuclear Emergency,

detailed field monitoring is the most important !