JpGU-AGU Joint Meeting 2017

Presentation information

[EJ] Oral

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

[M-AG34] [EJ] Dynamics of radionuclides emitted from Fukuchima Dai-ichi Nuclear Power Plant in the environment

Thu. May 25, 2017 10:45 AM - 12:15 PM Convention Hall A (International Conference Hall 2F)

convener:Kazuyuki Kita(Faculty of Science, Ibaraki University), Yuichi Onda(Center for Research on Isotopes and Environmental Dynamics, University of Tsukuba), Yasuhito Igarashi(Atmospheric Environment and Applied Meteorology Research Department, Meteorological Research Institute), Masatoshi Yamada(Institute of Radiation Emergency Medicine, Hirosaki University), Chairperson:Haruka Minowa(The Jikei University School of Medicine), Chairperson:Hiroaki Kato(Tsukuba University)

12:00 PM - 12:15 PM

[MAG34-12] The rapid deline of Cs-137 concentration in Fukushima rivers

*Yuichi Onda1, Keisuke Taniguchi2, Yoshifumi Wakiyama3 (1.Center for Research on Isotopes and Environmental Dynamics, University of Tsukuba, 2.Fukushima Prefectural Centre for Environmental Creation, 3.Institute of Environmental Radioactivity, Fukushima University)

Keywords:Cs-137, Fukushima NPP accident, runoff from rivers

The Fukushima Daiichi Nuclear Power Plant accident has released massive amount of radiocesium into the terrestrial environment, and the radiocecium have been transferred through terrestrial hydrological pathways in the last 5 years. The 137Cs attached fine particle of soil has been by washing off by erosion, then transported by river in which particulate (suspended) materials, play the 90-99% of the transported materials in Japanese rivers.
In the Chernobyl affected area, land use has been found to be affected the cleanup of the contaminated terrestrial environment , but precipitation and the land use is quite different affected by the radionuclides by FDNPP accident. Here we show the results by intensive field monitoring campaign, started in June, 2011, 3 months after the accident, monitoring 30 river stations for detailed monitoring of activity concentration of radiocesium in suspended sediment and their flux flown through the river.
Total 13 TBq of Cs have been transported to ocean from Abukuma river, this corresponds to 2.5 % of the total fallout from July 2011 to August 2015. Analysis of the riverine transport by upstream landuse reveals that higher percentage of Paddy field having largest rate of decline and also the highest flux, but the forest area showing lowest decline and smallest flux flowing downstream. The entrainment coefficient of dissolved water is quite low; due to
high initial decrease by active landuses, combining with high flux, typically 1 order lower than the lower end by the report of Chernobyl affected area, suggesting the rapid recovery of Fukushima contamination. We also analyze the effect of decontamination works on the activity and flux of the suspended sediment in the rivers.