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Otosaka, Shigeyoshi*; Misono, Toshiharu; Dohi, Terumi; Tsuruta, Tadahiko; Suzuki, Takashi
no journal, ,
In the coastal sediment off Fukushima, radionuclide-bound suspended particles are continuously supplied from the land through rivers, and the relative amount of the riverine input of the radionuclides in the coastal area increases with time. In the collaborative project in FY2019, we analyzed the characteristics of sinking particles collected at the shelf edge region (bottom depth: 200 m) southeast of the Fukushima Daiichi Nuclear Power Station, and outlined the transport processes of the particulate radionuclides in the coast to the offshore sea area. In FY2020, the reservoir effect of particulate radionuclides in the estuary and coastal areas were examined by conducting analysis of sinking particles in the nearshore and comparing the results with the characteristics of the shelf edge particles. The EPMA analysis of the nearshore particles found that almost no organic particles preserved in the estuary. It was considered that the organic particles found in the shelf edge area were either quickly removed from the estuary by horizontal transport or produced by organisms on the offshore surface.
Katengeza, E.*; Sanada, Yukihisa; Ochi, Kotaro; Iimoto, Takeshi*
no journal, ,
Yamada, Ryohei; Hashimoto, Hiroki*; Tamakuma, Yuki*; Hosoda, Masahiro*; Tokonami, Shinji*
no journal, ,
no abstracts in English
Miura, Tomisato*; Nakanishi, Takahiro; Sakuma, Kazuyuki
no journal, ,
From the analysis of yamame trout and aquatic insects inhabiting the Ukedo River system, it is speculated that the main migration route to yamame trout is via non-carnivorous aquatic insects. And, analysis of the yamame trout pond revealed a negative correlation between yamame trout body weight and radiocesium concentration, suggesting that individuals unable to receive non-contaminated food prey on benthos inhabiting the bottom of the pond. In this study, we analyze the concentration and stable isotope composition of radiocesium in yamame trout, aquatic insects, and benthos, and analyze the migration route of radiocesium to yamame trout.
Ochiai, Shinya*; Nagao, Seiya*; Nakanishi, Takahiro; Tsuruta, Tadahiko; Misono, Toshiharu; Watanabe, Shun*; Suzuki, Kyuma*; Tomihara, Seiichi*
no journal, ,
We investigated the controlling factors of radiocesium derived from the nuclear accident in each river systems in Fukushima Prefecture and the surrounding area. Dissolved 
Cs concentration / Cs deposition ratio tended to be higher in the Tone River and lower in the Natsui River than in the Abukuma River. Dissolved Cs concentration generally decreases exponentially, but the half-life is shorter in the Natsui River and longer in the Tone River than in the Abukuma River.