EGU2020-22136, updated on 20 Jan 2021
EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Rain-enhanced/induced bioecological resuspension of radiocaesium in a polluted forest in Fukushima

Yasuhito Igarashi1, Kazuyuki Kita2, Takashi Kinase3, Naho Hayashi2, Masahide Ishizuka4, Kouji Adachi3, Motoo Koitabashi5, and Yuichi Onda6
Yasuhito Igarashi et al.
  • 1Kyoto University, Institute for Integrated Radiation and Nuclear Science, Division of Nuclear Engineering Science, 2-chome, Asashiro-Nishi, Kumatori, Osaka, 590-0494 Japan (
  • 2College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512 Japan
  • 3Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052 Japan
  • 4Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa, 761-0396 Japan
  • 5Forage Crop Protection Group, Division of Livestock Feeding and Management, Central Region Agricultural Research Center, National Agriculture and Food Research Organization, 768 Senbonmatsu, Nasushiobara, Tochigi 329-2793, Japan
  • 6Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577 Japan

It is the conventional understanding that rain removes aerosols from the atmosphere. However, the question of whether rain plays a role in releasing aerosols to the atmosphere has recently been posed by several researchers. In the present study, we show the additional evidence for rain-enhanced/induced aerosol emissions in a forest environment: the occurrence of radiocaesium-bearing aerosols in a Fukushima forest due to rain. We carried out general radioactive aerosol observations in a typical mountainous village area within the exclusion zone in Fukushima Prefecture to determine the impacts and major players of the resuspension of radiocaesium originally from the nuclear accident in March 2011. We also conducted sampling according to the weather (with and without rain conditions) inside a forest to clarify the atmospheric radiocaesium source from the polluted forest. Thus, we found that rain enhances/induces bursts of radiocaesium-bearing aerosols in forests in Fukushima. With further investigations, we found that the fungal spore sources of resuspended radiocaesium under rainy weather seemed to differ from those under nonrainy weather. Larger fungal particles (possibly conidia-ascospore) are probably emitted during rainy conditions than during nonrainy weather, suggesting that the splash generation by rain droplets is the major mechanism of the suspension of radiocaesium-bearing mould-like fungi. Fungal spores can function as ice and cloud condensation nuclei and cause allergies, and fungal inocula may have a significant impact on agriculture. Therefore, the present findings indicate that radiocaesium could be used as a tracer in research fields such as forest ecology, meteorology, climatology, public hygiene and agriculture.

How to cite: Igarashi, Y., Kita, K., Kinase, T., Hayashi, N., Ishizuka, M., Adachi, K., Koitabashi, M., and Onda, Y.: Rain-enhanced/induced bioecological resuspension of radiocaesium in a polluted forest in Fukushima, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22136,, 2020