Ecological Half-Lives of Radiocesium in 16 Species in Marine Biota after the TEPCO's Fukushima Daiichi Nuclear Power Plant Accident

摘要

TEPCO's Fukushima Daiichi Nuclear Power Plant (FDNPP) accident of March 2011 caused the discharge of a considerable quantity of radionudides, including ~(137)Cs. Because of its long half-life (30.17 years), the fate of ~(137)Cs in the marine biota is of great interest This study aims to evaluate, using food monitoring data, ecological half-lives (T_(eco)) of ~(137)Cs in marine biota caught offshore of Fukushima. The data were categorized into two regional groups (north and south) with respect to the FDNPP site, and the regional ~(137)Cs concentration trend and estimated T_(eco) in the marine biota were appraised. Although the ~(137)Cs concentration in the seawater in the south was higher than that in the north, T_(eco) values remained relatively consistent among common species of both regions. T_(eco) was then compared to biological half-life (T_b) estimated in laboratory settings. The ratios of T_(eco) were inconsistent among different groups of marine species. The ratios of T_(eco)/T_b for brown seaweed and bivalves were approximately 1, and the ratios of T_(eco)/T_b for demersal fish ranged from 4.4 to 16.1. The reasons for different ratios of T_(eco) and T_b values may be attributed to environmental and ecological factors, such as different trophic levels.