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Decay corrected accumulative fallout of 137Csderived from atmospheric weapons tests as of 1970

Michio Aoyama, Katsumi Hirose and Yasuhito Igarashi, Re-construction and updating our understanding on the globalweapons tests 137 Cs fallout, Journal of Environmental

Monitoring , 8, 431-438, 2006.

In Northern Hemisphere765 79 PBq 1970In the North Pacific Ocean

290

30 PBq

197069 7 PBq 2011

Chernobyl accident 1986

85 PBq

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A pathway of weapons tests derived137 Cs in the North Pacific Ocean,

tracer of sea water movement

Fig. S2 Possible pathway of 137 Cs in the Pacific Ocean based on 3-Dobservations of 137 Cs in 2000s (Aoyama et al., 2013)

We can expect that Fukushimaorigin radiocaesium should gosame pathway

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Pathways of Fukushima derivedradionuclides to the Ocean

Atmospheric deposition Direct release Groundwater discharge River runoff

TEPCO Press release

137 Cs : 1.8E+12 Bq/m 3

Simulated atmospheric deposition of137 Cs (Bq m -2) (by Masingar II of MRI)(Aoyama et al., in preparation)

4

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Boiling Water Reactor Systems "NuclearReactor Concepts" Workshop Manual,U.S. NRC

3.6 0.7 PBq to the ocean(Tsumune et al., 2013)

14 17 PBq to the atmosphere

700 PBq was in the three core 140 PBq in stagnant water(Nishihara et al.,, 2011) (Nishihara et al., 2011)

140 PBq in stagnant water

12 - 15 PBq to the ocean

137 Cs mass balance

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More than 99% of released radioaesium to the oceanwas transported offshore, then to the ocean interior

30 GBq day -1Revised estimation

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R/V Mirai

NYK AQUARIUS

R/V Hakuho Maru

NYK Heijin

Sampling locations during the period fromMarch 2011 to Oct. 2012

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l l

(Aoyama et al., BG 10 3067-3078, 2013)

Apr-Jun2011

Jul-Sep2011

Oct-Dec2011

Jan-Mar2012

Surface speed of contaminated water ca. 7 km day -1

8

X

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0 5 10 15 20 250

100

200

300400

500

600700

800

KS1109-3101

RF1205-4418

134Cs / Bq m -3

D e p

t h / m Oxygen maximum

Sigma0=26.3Year 2011 2012Month 10 6

Bq m -2 Bq m -2

134Csinventory 2710+-210 2350+-190

0 - 200 m 2150 520

Deeper than200 m 520 1830

Oct. 2011

ver time, Cs moves east and subducted in the ocean interior

June 2012

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Bq m -3

137 Cs cross section along 165 E in June 2012

Start of travel into ocean interior N

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Possible pathway of Fukushima derivedradionuclides in the North Pacific Ocean

Fig. S2 Possible pathway of 137 Cs in the Pacific Ocean

We found start of travel of Fukushima derivedradioactivity in the ocean interior.

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Summary of budget of 137 Csfor pre- and after the Fukushima accident

Main portion of Fukushima derived radioactivityalready subducted into the ocean interior and is

moving to southwest ward.