Exposures and effects in the marine environment after the Fukushima accident

Radiation doses to marine biota near the Fukushima Dai-ichi NPP have been estimated for the immediate aftermath and subsequent period of the accident. Dose estimations using monitoring data have been complemented by means of a dynamic transfer modelling, improving on the more traditional equilibrium transfer approach. Earlier assessments using equilibrium transfer models over-estimated the exposures in the immediate aftermath of the accident, whereas dynamic transfer modelling brings them more in line with the doses calculated from monitored activity concentrations in the biota. On that basis, marine biota populations in the vicinity of Fukushima do not seem to be at significant risk. The situation in the late post-accident period shows a tendency for lower exposures, but radiocaesium in sediments and biota persists to this day, with some organisms inhabiting local hotspots. Little is known about how long radionuclides will continue to remain in the local environment, owing to limited knowledge on the effects of chronic radiation to marine organisms. Therefore, the marine environment at Fukushima needs to be further studied. The Fukushima nuclear accident remains an on-going problem for marine radioecology, requiring constant re-evaluation of the cumulative extent of contamination and effects on the environment for years to come.