@misc{oai:repo.qst.go.jp:00085489,
 author = {Tateda, Y. and Tsumune, D. and Kobayashi, T. and Ishimaru, T. and Ito, Y. and Kanda, J. and Uchida, K. and Aoyama, M, and hamajima, Y. and Tatsuo, Aono and Suzuki, S. and Tatsuo, Aono},
 month = {Dec},
 note = {The radiocesium levels in coastal waters off Fukushima deceased greatly after the accident of the nuclear power accident 1FNPP, whereas depuration in marine fish was different, especially of rockfish. Matstumoto et al., 2015 suggested that excretion of 137Cs was slower than expected;; Ishimaru et al., 2019 demonstrated that stable cesium content in the rockfish was comparatively higher than those of other species; high content of radiocesium in prey organism of rock fish. Howeverthe detailed clarification of the mechanism of its high level and slow depuration was not enough clarified. It was expected to confirm the excretion rate of radiocesium from the rockfish furthermore; determination of the transition state of radiocesium between rockfish and environment; examination of the contribution of radiocesium transfer along food chain focusing on bio-availability.
137
In this study, Cs concentrations in demersal fish
including rock fish collected from southern coastal waters of 1FNPP to identify the radiocesium transfer state of equilibrated or transition. Concerning the cesium bio-kinetics in the rockfish was examined the depuration rate of radiocesium by measuring the radioactivity of 137Cs in living fish by Ge detector under experimental condition to identify the biological half-life. With respect to radiocesium food chain transfer, labile fraction of 137Cs in prey organisms and stomach content were examined by collected samples from off Fukushima. Finally, the dynamic biological transfer model was applied to reconstruct the 137Cs level in rockfish using derived parameters, and the theoretically derived mechanism was verified by the observed time-series of 137Cs concentrations in the rockfish.
As a result, there was no significant difference among stable cesium content in muscle of three demersal fish including the rockfish. The biological half-lives suggested as 140-220 days by the modelling study (Ishimaru et al., 2019) was revised to be approximately 210 days from the long-term experiment of - spectroscopy of 137Cs in living rockfish measurement. The result demonstrated that the biological half-life of radiocdesium in the rockfish was evaluated as slower than 90 days for teleost species derived from the radio-isotope experiment. The 137Cs levels seawater and of the stomach content and muscle of the rockfish collectedfrom southern area of the 1FNPP were 3-7 mBq/L, 1-2 Bq/kg-wet, 2-7 Bq /kg-wet. These results demonstrated that food chain transfer of 137Cs to the rockfish was still substantial to partly keep the radioactivity higher than the levels of pre-Fukushima, whereas it was not found why the radiocesium content in prey organisms higher than theoretical understanding suing seawater level., 6th International Conference on Environmental Radioactivity},
 title = {Determining factors of radio-cesium bio-kinetics in rockfish off Fukushima},
 year = {2021}
}