Artificial radionuclides in neon flying squid from the northwestern Pacific in 2011 following the Fukushima accident

Abstract

In order to better understand the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on a commercial marine species, neon flying squid (Ommastrephes bartramii) samples obtained from the northwestern Pacific in November 2011 were analyzed for a range of artificial and natural radionuclides (Cs-134, Cs-137, Ag-110m, U-238, Ra-226, and K-40). Short-lived radionuclides Cs-134 and Ag-110m released from the FDNPP accident were found in the samples, with an extremely high water-to-organism concentration ratio for Ag-110m ( > 2.9×104). While accident-derived radionuclides were present, their associated dose rates for the squid were far lower than the relevant benchmark of 10 µGy h−1. For human consumers ingesting these squid, the dose contribution from natural radionuclides, including Po-210, was far greater ( > 99.9 %) than that of Fukushima-accident radionuclides ( < 0.1 %). The whole-body to tissue and whole-body to gut concentration ratios were calculated and reported, providing a simple method to estimate the whole-body concentration in environmental monitoring programs, and filling a data gap for concentration ratios in cephalopods. Our results help fill data gaps in uptake of nuclear power plant radionuclides in the commercially important Cephalopoda class and add to scarce data on open-ocean nekton in the northwestern Pacific shortly after the Fukushima accident.