Assesment of radioecological state of the Far Eastern Seas of Russia in connection with a polluted water discharge from Fukushima-1 NPP (cruise no. 71 of RV “Akademik Oparin”)

During the cruise of RV “Akademik Oparin” an assessment of radioecological state of the Pacific Ocean east of Japan and Kuril Islands as well as Okhotsk and Japan seas was conducted in connection with polluted water discharge from Fukushima-1 NPP. Results of the first samples of surface analysis showed tritium content as 0.36–0.78 tritium units (0.04–0.09 Bk/l). The highest concentrations were found in the Kuroshio Extension stream and in the area of Southern Kuril Islands. Meanwhile it is ten thousands time lower than radio security norm. In the cruise samples of water, bottom sediments and marine biota were prepared to analyze radioisotopes of cesium, strontium, led, radium and others. Large volume of hydrographic, chemical, biological, gas-geochemical, mercury measurements and samplings was implemented. Mooring systems were recovered and deployed again. New data on water state and dynamics of the study region, as well as biogeochemical parameters and their interannual variability in association with climate change and increasing anthropogenic load were received.