[2M01-08] Environmental Radioactivity 2

[2M03] Investigation on distribution of radioactive substances in Fukushima

(9)Effect of stemflow on deep infiltration of ¹³⁷Cs in the cedar stand in Namie Town, Fukushima Prefecture

*Hikaru Iida¹, Hiroaki Kato¹, Tomoki Shinozuka¹, Satoru Akaiwa¹, Yuma Niwano¹, Yuichi Onda¹ (1. Univ. of Tsukuba)

Keywords:Stemflow, Throughfall, Infiltration water, Radiocesium, Fukushima Dai-ichi Nuclear Power Plant accident

The concentration of stemflow into the area of tree trunks and the influence of preferential flow along the tree root on the hydrological cycle have been reported. In this study, evaluation the effects of stemflow and throughfall on soil infiltration, we collected water stemflow, throughfall, and infiltration water and analyzed the radioactivity of ¹³⁷Cs in the cedar stand in Namie Town, Fukushima Prefecture. Infiltration water was collected at the base of the tree trunks (Rd), where the high ¹³⁷Cs concentration flows in, and between the trees (Bt), and the ¹³⁷Cs flux was 2.5 times higher at 5 cm depth and 3.7 times higher at 20 cm depth in Rd. And, the infiltration for each event was also compared by the presence or absence of stemflow. The results showed that the amount of water was greater at 20 cm depth in Rd when stemflow occurred than when did not occur. Therefore, it is suggested that the rainwater from the stemflow may have caused infiltration into the deep soil.