[1I01-07] Environmental Dynamics 1

[1I02] Investigation on distribution of radioactive substances in Fukushima

(2) Estimation of the discharge pathway of dissolved Cs-137 in the forest headwater catchment in the high deposition area

*Yuma Niwano¹, Hiroaki Kato¹, Satoru Akaiwa¹, Donovan Anderson¹, Hikaru Iida¹, Miyu Nakanishi¹, Yuichi Onda¹ (1. Univ. of Tsukuba)

Keywords:Fukushima Dai-ichi Nuclear Power Plant accident, dissolved cesium 137, surface water, subsurface water, headwater catchment

We investigated changes in dissolved Cs-137 concentrations in slope subsurface water and surface water through detailed hydrological observations in order to estimate the discharge pathway of dissolved Cs-137 in the forest headwater catchment of Namie, Fukushima Prefecture, a high deposition area. During base flow conditions, water samples were taken from slope subsurface water and surface water. During outflow events, changes in groundwater level and subsurface water flow were observed using piezometers and groundwater observation wells, and surface water was sampled using an automatic water sampler. The samples were measured in the laboratory using a germanium semiconductor detector to determine the concentration of dissolved Cs-137. We report the results of our analysis based on the obtained data, especially on the increase of dissolved Cs-137 concentration in surface water and the change of subsurface water flow on the slope at the time of water discharge.