Accumulation of radioactive caesium in the Japanese eel Anguilla japonica in Northeast Japan after the Fukushima nuclear accident.

The unpredicted nuclear accident by the Fukushima Daiichi Nuclear Power Plant (F1NPP) is a global concern for human health and ecosystems. In the present study, five-year fluctuations and accumulations of Cs, 134Cs and 137Cs in the Japanese eel were examined in Northeast Japan. The eel is one of the most important research subjects in fishery resources in Asia. The total radioactive Cs, 134Cs and 137Cs levels in the fish gradually decreased throughout the five-year study period after the F1NPP accident. A faster decay rate was found for 134Cs (10–15%) for five years after the F1NPP accident, and the decay of 137Cs (30–90%) was slower during the five years. The difference of decay rates between radiocaesiums might be explained by their different half-lives. The F1NPP derived 134Cs contamination might cease unless fresh input may be detected, and 137Cs might still be distributed and remain in the natural environment. [ABSTRACT FROM AUTHOR]