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Cs washoff from bare land in Fukushima五十嵐 康記*; 恩田 裕一*; 脇山 義史*; 吉村 和也; 加藤 弘亮*; 小塚 翔平*; 馬目 凌*
Science of the Total Environment, 769, p.144706_1 - 144706_9, 2021/05
被引用回数：2 パーセンタイル：13.39(Environmental Sciences)The impact of freeze-thaw processes and subsequent runoff affecting the Cs-137 (Cs) flux and concentration in sediment discharge were revealed in bareland erosion plot following the Fukushima Nuclear Power Plant accident by detailed monitoring and laser scanner measurement on the soil surface. We found that surface topographic changes due to the frost-heaving during the winter- spring period, and rill formation during the summer. We also found the evident seasonal changes in Cs concentration; high during the early spring and gradually decreased thereafter, then surface runoff from the plot frequently occurred during spring and autumn when rainfall was high and reached a maximum in summer.
脇山 義史*; 恩田 裕一*; 吉村 和也; 中村 典子*; 馬目 凌*
no journal, ,
This study shows approximately three years observation results of plot-scale Cs-137 wash-off at various land uses in Kawamata town after the accident of FDNPP. Soil erosion rate were positively correlated with vegetation cover on undisturbed soils, whereas high erosion rate were found on cultivated farmlands even with similar vegetation cover to uncultivated farmlands. Annual Cs-137 wash-off rate ranged from 0.003 to 9.3 %/year and the largest was from uncultivated farmland followed by cultivated farmlands. Decreasing trends of Cs-137 concentration were found on uncultivated farmlands, whereas no trend was found on other plots. Our results suggest that the active soil erosion results in decrease in Cs-137 concentration of sediments on uncultivated slopes, while cultivation resulted in the no trend of temporal decrease in Cs-137 concentration due to constant vertical distribution of Cs-137.
脇山 義史*; 馬目 凌*; 恩田 裕一*; 吉村 和也
no journal, ,
本研究では、斜面スケールでの土砂移動に伴う放射性セシウムの移動プロセスを明らかにすることを目的として、福島原発により放射性セシウムが沈着した地点に土壌侵食プロットを設置して土砂およびCs-137流出量の観測を行うとともにレーザープロファイラによる地表面の地形変化を追跡し、土砂移動に伴うCs-137流出の時間変化および季節性について考察を行った。本研究結果は、放射性セシウムの移行には季節性があることを示しており、将来予測の精度向上のためには斜面スケールにおけるCs-137移動プロセスについての複数年の観測が有用であることが示唆された。
脇山 義史*; 馬目 凌*; 恩田 裕一*; 吉村 和也
no journal, ,
This study presents a three years' Cs-137 wash-off observation and morphological surveys on a soil erosion in area affected by the accident of Fukushima nuclear power plant to describe detailed processes of Cs-137 wash-off. Cs-137 concentration varied enormously and it appeared to decrease gradually from spring to autumn and increased again after winter. Based on the photos and scan data of soil surface, the expansions of a rill from spring to summer and elevations of soil surface from winter to spring were found. Our analysis suggests that freezing and thawing cycles resulted in high Cs-137 concentration of sediments during winter, whereas expansion of rill makes decrease in Cs-137 concentration in warm seasons.
Cs wash-off from bareland in Fukushima五十嵐 康記*; 恩田 裕一*; 脇山 義史*; 吉村 和也; 加藤 弘亮*; 小塚 翔平*; 馬目 凌*
no journal, ,
The impact of freeze-thaw processes and subsequent runoff affecting the Cs flux and concentration in sediment discharge were revealed in bareland erosion plot following the Fukushima nuclear power plant accident by detailed monitoring and laser scanner measurement on the soil surface. We found that surface topographic changes due to the frost-heaving during the winter-spring period, and rill formation during the summer. We also found the evident seasonal changes in Cs concentration; high during the early spring and gradually decreased thereafter, then surface runoff from the plot frequently occurred during spring and autumn when rainfall was high and reached a maximum in summer. From these results, the higher Cs concentration in spring was caused by a mixture of unstable surface sediment following freeze- thaw processes and then transported in the early spring, but erosion amount is not significant because of the less rainfall event. The sediment with a lower Cs concentration, which was supplied from the rill erosion and its expansion, was wash-offed during the summer, contributing most of the flux from erosion in bareland in Fukushima region.
