東京電力福島第一原発事故の影響評価を中心とした海産動物プランクトンの人工放射性核種に関する研究（総説）

抄録

Anthropogenic radionuclides have been deposited into the ocean since the era of atmospheric nuclear weapon tests in the 1950s. In 2011, the Fukushima Dai-ichi nuclear power plant accident resulted in additional release of anthropogenic radionuclides into marine ecosystems. This review summarizes field studies concerning anthropogenic radionuclides in zooplankton before and after the Fukushima accident. Before the Fukushima accident, the concentrations of cesium-137 (¹³⁷Cs) in zooplankton around Japan were 10^-2 Bq/kg-wet, and the concentration ratios of them were in the order of 10¹. The concentration ratios of ¹³⁷Cs for zooplankton reported around Japan were comparable to those values reported from European areas, such as the Mediterranean Sea. These results suggest that dynamic equilibrium had been reached between zooplankton and surrounding seawater before the Fukushima accident. The Fukushima accident resulted in elevation of concentrations of ¹³⁷Cs in coastal seawater by three to four orders of magnitude off Fukushima prefecture soon after the accident, and decreased rapidly. The concentration of ¹³⁷Cs in zooplankton was also elevated, and their temporal change （decrease with time） seemed to be correlated with that of seawater. The scatter plots between concentrations of ¹³⁷Cs in seawater and apparent concentration ratio of ¹³⁷Cs for zooplankton could be good indicators of the changes in ¹³⁷Cs contamination in zooplankton from the beginning of the Fukushima accident to the restoration phase.