[1I01-07] Environmental Dynamics 1

[1I04] Investigation on distribution of radioactive substances in Fukushima

(4) Temporal changes in the vertical distribution of ¹³⁷Cs and its downward migration mechanisms in forest soils

*Junko Takahashi¹, Daichi Hihara¹, Takuya Sasaki¹, Satoshi Iguchi¹, Yuichi Onda¹ (1. Univ. of Tsukuba)

Keywords:vertical distribution of Cs-137, relaxation depth , downward migration mechanisms, rainfall infiltration

We show the results of ongoing monitoring of vertical distribution of Cs-137 in forest soil in the Yamakiya district, Kawamata Town, Fukushima Prefecture, since 2011, and estimate the amount of downward migration calculated based on the temporal changes in vertical distribution. In addition, Cs-137 flux by rainfall infiltration water was measured using zero-tension lysimeters installed under the litter layer and at three depths (5 cm, 10 cm, and 20 cm in soil). By comparing these measurements, the contribution of rainfall infiltration to downward migration was estimated.