Estimation of radioactive 137-cesium transportation by litterfall, stemflow and through fall in the forests of Fukushima

摘要

Since the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011, large areas of the forests around Fukushima have become highly contaminated by radioactive nuclides. To predict the future dynamics of radioactive cesium (Cs-137) in the forest catchment, it is important to measure each component of its movement within the forest. Two years after the accident, we estimated the annual transportation of Cs-137 from the forest canopy to the floor by litterfall, throughfall and stemflow. Seasonal variations in Cs-137 transportation and differences between forests types were also determined. The total amount of Cs-137 transported from the canopy to the floor in two deciduous and cedar plantation forests ranged between 3.9 and 11.0 kBq m(-2) year(-1). We also observed that Cs-137 transportation with litterfall increased in the defoliation period, simply because of the increased amount of litterfall. Cs-137 transportation with throughfall and stemflow increased in the rainy season, and Cs-137 flux by litterfall was higher in cedar plantation compared with that of mixed deciduous forest, while the opposite result was obtained for stemflow. (C) 2015 Elsevier Ltd. All rights reserved.