EGU2020-12301
https://doi.org/10.5194/egusphere-egu2020-12301
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Mass balance of radiocaesium derived from Fukushima accident and estimation of latest fluxes among atmosphere, land and ocean

Michio Aoyama1, Daisuke Tsumune2, Yayoi Inomata3, and Yutaka Tateda4
Michio Aoyama et al.
  • 1Univ. of Tsukuba, Center for Research in Isotopes and Environmental Dynamics, Tsukuba, Japan (michio.aoyama@ied.tsukuba.ac.jp)
  • 2Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (tsumune@criepi.denken.or.jp)
  • 3Institute of Nature and Environmental Technology, Kanazawa University (yinomata@se.kanazawa-u.ac.jp)
  • 4Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (tateda@criepi.denken.or.jp)

Regarding with amount of movement of 137Cs from domain to domain for several years after the accident, we also evaluated that the amount of 137Cs transported by the rivers might be 40 TBq which is corresponding to less than 1.3 % of deposited 137Cs. For resuspension, the annual deposition of 137Cs at Okuma during the period from 2014 to 2018 means that 4 TBq year-1to 10 TBq year-1should be amount of resuspension from land to atmosphere and this amount correspond to 0.1 % to 0.3 % of total deposition of 137Cs on land in Japan. The 137Cs activity concentration at 56N canal in 2016-2018 correspond to 137Cs discharge of 0.73 TBq year-1to 1.0 TBq year-1from FNPP1 site to open water. The integrated amount of FNPP1 derived 137Cs that entered the Sea of Japan, SOJ, until 2017 was 0.27 ± 0.02 PBq, which is 6.4 % of the estimated total amount of FNPP1-derived 137Cs in the STMW in the North Pacific. The integrated amount of FNPP1-derived 137Cs that returned to the North Pacific Ocean through the Tsugaru Strait from SOJ was 0.11 ± 0.01 PBq, 42 % of the total amount of FNPP1-derived 137Cs transported to the SOJ. As a result of decontamination works, 134 TBq of 137Cs was removed from surface soil until February 2019 which correspond to 4 % of deposited 137Cs on land in Japan. Therefore, the largest transport amount of 137Cs was 270 ± 2 TBq from STMW in the North Pacific to SOJ until 2017, and the second largest was decontamination work by which work about 134 TBq was removed from surface soil on land until Feb. 2019. Fluvial transport by rivers contributed about 40 TBq since June 2011 until 2016.

How to cite: Aoyama, M., Tsumune, D., Inomata, Y., and Tateda, Y.: Mass balance of radiocaesium derived from Fukushima accident and estimation of latest fluxes among atmosphere, land and ocean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12301, https://doi.org/10.5194/egusphere-egu2020-12301, 2020

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Display material version 2 – uploaded on 03 May 2020
I have changed only last slide and make the pdf as protected.
  • CC1: Comment on EGU2020-12301, Olivier Evrard, 08 May 2020

    Dear Aoyama-sensei, many thanks for sharing this estimation of the Fukushima Cs-137 mass balance. I had a question regarding the 134 TBq-estimation of Cs-137 removed by decontamination works (although I found the calculation details in your article published this year in JER...) I had in mind (but maybe it is not correct) that cultivated land (where decontamination works were concentrated) covered ~8-10% of the total surface area and you calculate that decontamination led to the removal of ~4% of initial Cs-137 fallout. Do you agree with the estimation of ~8-10% of the surface covered by agricultural land in the main fallout area and, if so, how can we explain the mismatch between both figures (4% vs. 8-10%)?

    I also wondered whether you could clarify what you mean with 'Cs-137 resuspension from forests'? What type of processes are you referring to?

    Many thanks for your feedback! Kind regards, Olivier Evrard

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