[2A08-12] Environmental Radioactivity and Monitoring 2

[2A12] Investigation on distribution of radioactive substances in Fukushima

(12)Influence of stemflow on the infiltration of radioactive cesium into the soils in a cedar forest in Namie town, Fukushima Prefecture

*Hikaru Iida¹, Hiroaki Kato¹, Tomoki Shinozuka¹, Satoru Akaiwa¹, Yuichi Onda¹ (1. Univ. of Tsukuba)

Keywords:stemflow, forest soil, infiltration water, Fukushima Daiichi Nuclear Power Plant accident, radioactive cesium

Stemflow takes important role on the spatial distribution of radioactive cesium in the forest because it brings intensive rainwater input. However, there are few studies on the effects of stemflow in infiltration mechanisms by collecting of soil water. In this study, soil water near the tree roots (Rd) and far from the trunk (Bt) are collected from a cedar forest in Namie Town, Fukushima Prefecture, and dissolved ¹³⁷Cs concentration was measured. As a result, the mean amount of infiltration water which was normalized for rainfall depth during the whole sampling period was 1.4 times and 3.0 times larger, the average dissolved ¹³⁷Cs concentration was 1.6 times and 1.5 times larger at 5 cm and 20 cm depth for the Rd than the Bt, respectively. This suggests that infiltration water flux and dissolved ¹³⁷Cs concentration can be increased due to contribution of stemflow input at the base of tree trunk.