Radiocesium wash-off associated with soil erosion from various land uses after the Fukushima Dai-ichi NPP accident

福島第一原子力発電所事故後の様々な土地利用からの土壌浸食に伴う放射性セシウムの流出

脇山 義史*; 恩田 裕一*; 吉村 和也  ; 加藤 弘亮*

Wakiyama, Yoshifumi*; Onda, Yuichi*; Yoshimura, Kazuya; Kato, Hiroaki*

This study presents two-year observation of soil erosion and radiocesium wash-off to quantify differences in radiocesium behavior in various land uses. High erodibilities and relatively low values of radiocesium wash-off in cultivated farmlands can be attributed to the mixing of surface soil by ploughing. It was found that the total solid wash-off coefficient of radiocesium from farmlands is high and for 2 years period of time after the accident reaches 10%. Generally high precipitation in the region and steep slopes promote higher wash-off of radiocesium as compared to the Chernobyl case. Also, normalized wash-off coefficients exhibited relatively less volatility than erodibilities in thelandscapes. These results suggest that soil erosion management is crucial for mitigating risks of radiocesium.