Fallout volume and litter type affect Cs-137 concentration difference in litter between forest and stream environments

摘要

It is important to understand the changes in the Cs-137 concentration in litter through leaching when considering that Cs-137 is transferred from basal food resources to animals in forested streams. We found that the difference of Cs-137 activity concentration in litter between forest and stream was associated with both litter type and Cs-137 fallout volume around Fukushima, Japan. The Cs-137 activity concentrations in the litter of evergreen conifers tended to be greater than those in the litter of broad-leaved deciduous trees because of the absence of deciduous leaves during the fallout period in March 2011. Moreover, Cs-137 activity concentrations in forest litter were greater with respect to the Cs-137 fallout volume. The Cs-137 activity concentrations in stream litter were much lower than those in forest litter when those in forest litter were higher. The Cs-137 leaching patterns indicated that the differences in Cs-137 activity concentration between forest and stream litter could change with changes in both fallout volume and litter type. Because litter is an important basal food resource in the food webs of both forests and streams, the Cs-137 concentration gradient reflects to possible Cs-137 transfer from lower to higher trophic animals. Our findings will improve our understanding of the spatial heterogeneity and variability of Cs-137 concentrations in animals resident to the contaminated landscape. (C) 2016 Elsevier Ltd. All rights reserved.