Content of Technogenic Radionuclides in Water, Bottom Sediments, and Benthos of the Kara Sea and Shallow Bays of the Novaya Zemlya Archipelago

The radioactive cesium content determined in sea water of the Novaya Zemlya archipelago bays and offshore zone during the expedition of R/V Akademik Mstislav Keldysh in 2016 year seemed to correspond to the global fallout (1 Bq/m(3)). The plutonium content in water is slightly higher. The activity of neptunium in water is an order of magnitude higher than that of plutonium (0.76-1.89 Bq/m(3)), although its content in the global fallout is almost two orders of magnitude lower than the plutonium content. The activity of plutonium in the bottom sediments of the Kara Sea is 0.2-3.8 Bq/kg, while that of radioactive cesium is 0.5-0.6 Bq/kg, reaching 21 Bq/kg in the Yenisei mouth. Analysis of benthic samples showed that the content of radioactive cesium and plutonium in samples taken in the bays of the Novaya Zemlya archipelago is below the detection limit. The neptunium content in the benthic samples is within 1-80 Bq/kg wet weight. It was shown that the content of neptunium in benthos is one of the indicators of radioactive pollution of the marine environment.