Japan Geoscience Union Meeting 2016

Presentation information


Symbol M (Multidisciplinary and Interdisciplinary) » M-AG Applied Geosciences

[M-AG24] Dynamics of radionuclides emitted from Fukuchima Dai-ichi Nuclear Power Plant in the environment

Mon. May 23, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Kazuyuki Kita(Faculty of Science, Ibaraki University), Yuichi Onda(Center for Research on Isotopes and Environmental Dynamics, University of Tsukuba), Teruyuki Nakajima(Japan Aerospace Exploration Agency), Yasuhito Igarashi(Atmospheric Environment and Applied Meteorology Research Department, Meteorological Research Institute), Masatoshi Yamada(Institute of Radiation Emergency Medicine, Hirosaki University), Chisato Takenaka(Graduate School of Bioagricultural Sciences, Nagoya University), masayoshi yamamoto(Low Level Radioactivity Laboratory, Kanazawa University), Jota Kanda(Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology), Atsushi Shinohara(Osaka university)

5:15 PM - 6:30 PM

[MAG24-P03] Resuspension processes of Fukushima radioCs: Could fungal spore play a significant role?

*Yasuhito Igarashi1, Kazuyuki Kita2, Teruya Maki3, Chisato Takenaka4, Takeshi Kinase2, Kouji Adachi1, Mizuo Kajino1, Tsuyoshi Sekiyama1, Yuji Zaizen1, Masahide Ishizuka5, Kazuhiko Ninomiya6, Hiroshi Okochi7, Atsuyuki Sorimachi8 (1.Meteorological Research Institute, 2.Ibaraki University, 3.Kanazawa University, 4.Nagoya University, 5.Kagawa University, 6.Osaka University, 7.Waseda University, 8.Fukushima Medical University)

Keywords:the Fukushima Daiichi Nuclear Power Plant accident, Radioactive cesium, Resuspension, Bioaerosol, Dust

The authors have studied for atmospheric re-suspension of the radioactive cesium (Cs) originated from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in contaminated area by the accident to assess the atmospheric effect of the accident. As a result the authors came to know that 1) in summertime, Cs concentration increases (see Fig. 1) in such typical Japanese village-vicinity mountain area and that 2) radioactive particles in summer seem to be dust from its appearance and their optical micrograph, but on the contrary, we realized that most has biological origin from electron-microscopic view (Fig. 2). Taking into consideration the fact that true fungi concentrate Cs due to misidentifying Cs as potassium, we can assume that the fungal spore as the major contributing factor for resuspension.
Supposed that only fungal spore can carry 137Cs, estimating the 137Cs amount per spore under various assumptions; the value would be 5×10-10-3×10-7 Bq/fungal spore particle, in that case, the spore needs to be released at a rate of 9×103-5×105 particle/m2/sec from forests to support the present 137Cs in the air. This value is surprisingly 1-3 digits larger than the forest maximum value (387 particle/m2/sec) of the fungal spore emission rate given in Table 2, Sesartic & Dallafior (2011), suggesting a potentially large environmental impacts of the spore. Actually, number concentration of bio-aerosol would be reaching 5-8×105 particle/m3 in our preliminary observation during past summer in 2015 in a forest in Fukushima Prefecture, revealing that more bio-aerosol release could be occurring from Japanese forests than our expectation. Further, based on this postulation that fungal spore would be a major source of atmospheric Cs especially during summer, 137Cs concentration would be ranging 2.5×10-4-0.15 Bq/m3 air in the forest, which almost fits to the actual 137Cs concentration level shown in Fig. 1.