[1D15-20] Environmental Radioacitivty and Monitoring 3

[1D18] Investigation on distribution of radioactive substances in Fukushima

(14)Change of sediment sources in suspended sediments due to surfacedecontamination in the Niida river catchment area affected by theFukushima Daiichi nuclear power plant accident

*YUICHI Onda¹, Yuki Yamanaka¹, Yoshifumi Wakiyama², Keisuke Taniguchi³, Kazuya Yoshimura⁴ (1. CRiED, University of Tsukuba, 2. Institute of Environmental Radioactivity, Fukushima University, 3. Environmental Creation Center, Fukushima Prefecture, 4. JAEA)

Keywords:Decontamination works, soil erosion, Cs-137, river

The Fukushima Daiichi Nuclear Power Plant (FDNPP) on March 2011 accident released massive amounts of radiocesium into the terrestrial environment such as Cs-137 and Cs-134. The Niida river basin (265 km²) on the north eastern part of Fukushima prefecture is indeed a case in point. The river basin has a highly contaminated area on its upstream part and evacuation have been ordered, and the cropland and paddy field becomes grassland in the summer of 2011, but the downstream part has not contaminated so much. The upstream area of the basin had been subject to decontamination works, such as scraping surface soil and reversal tillage and so on, since 2012.