Ecosystem model-based approach for modeling the dynamics of 137Cstransfer to marine plankton populations: application to the western NorthPacific Ocean after the Fukushima nuclear power plant accident

[摘要] Huge amounts of radionuclides, especially ¹³⁷Cs, were released into thewestern North Pacific Ocean after the Fukushima nuclear power plant (FNPP)accident that occurred on 11 March 2011, resulting in contamination of themarine biota. In this study we developed a radioecological model to estimate¹³⁷Cs concentrations in phytoplankton and zooplankton populationsrepresenting the lower levels of the pelagic trophic chain. We coupled thismodel to a lower trophic level ecosystem model and an ocean circulation modelto take into account the site-specific environmental conditions in the area.The different radioecological parameters of the model were estimated bycalibration, and a sensitivity analysis to parameter uncertainties wascarried out, showing a high sensitivity of the model results, especially tothe ¹³⁷Cs concentration in seawater, to the rates of accumulation fromwater and to the radionuclide assimilation efficiency for zooplankton. Theresults of the ¹³⁷Cs concentrations in planktonic populations simulatedin this study were then validated through comparison with the dataavailable in the region after the accident. The model results have shown thatthe maximum concentrations in plankton after the accident were about 2 to4 orders of magnitude higher than those observed before the accident,depending on the distance from FNPP. Finally, the maximum ¹³⁷Cs absorbeddose rate for phyto- and zooplankton populations was estimated to be about5  ×  10⁻² µGy h⁻¹, and was, therefore, lowerthan the predicted no-effect dose rate (PNEDR) value of10 µGy h⁻¹ defined in the ERICA assessment approach.

[学科分类] 地球化学与岩石