Comparison of radioactive cesium contamination of lake water, bottom sediment, plankton, and freshwater fish among lakes of Fukushima Prefecture, Japan after the Fukushima fallout

Abstract

Levels of radiocesium (134Cs + 137Cs) contamination in lake water, bottom sediment, plankton, and fish were investigated in three geographically separated lakes in Fukushima Prefecture (Lake Hayama, Lake Akimoto, and Lake Tagokura) between June 2012 and November 2013. Levels of contamination differed among the three lakes, with the highest levels of each measured component in Lake Hayama, followed by Lake Akimoto, and the least contamination in Lake Tagokura. Among the lakes, the magnitude of contamination decreased with distance from the Fukushima Dai-ichi Nuclear Power Plant. Mean radiocesium concentrations were higher in piscivorous fish than in other fish, possibly reflecting differences in trophic level. The radiocesium concentrations in some fish species decreased significantly by 33–65 % during the period between 2012 and 2013. Radiocesium concentrations of the lake water, bottom sediment, plankton, and fish were significantly correlated with surface soil radiocesium content near lake sites.