Radioactive contamination in the marine environment adjacent to the outfall of the radioactive waste treatment plant at ATOMFLOT, northern Russia.

RTP "ATOMFLOT" is a civilian nuclear icebreaker base located on the Kola Bay of northwest Russia. The objectives of this study were to determine the distributions of man-made radionuclides in the marine environment adjacent to the base, to explain the form of the distributions in sediments and to derive information concerning the fate of radionuclides discharged from ATOMFLOT. Mean activity concentrations (d.w.) for surface sediment, of 63 Bq kg(-1 137Cs, 5.8 Bq kg(-1) 90Sr and 0.45 Bq kg(-1 239,240)Pu were measured. Filtered seawater activity levels were in the range of 3--6.9 Bq m(-3) 137Cs, 2.0-11.2 Bq m(-3) 90Sr, and 16-40 m Bq m(-3), 239,240Pu. Short-lived radionuclides were present at sediment depths in excess of 10cm indicating a high degree of sediment mixing. Correlations of radionuclide activity concentrations with grain-size appear to be absent; instead, the presence of relatively contaminated sediment appears to be related to the existence of radioactive particles.

Anthropogenic radionuclides in seawater of the Far Eastern Seas.

Large quantities of radioactive wastes have been dumped in the Far Eastern Seas by the former Soviet Union and the Russian Federation, and small amounts of radioactive wastes have been dumped by Japan and the Republic of Korea. In order to investigate the concentrations of anthropogenic radionuclides in the nine dumping areas, a second expedition was conducted in 1995 by Japan, the Republic of Korea, the Russian Federation and IAEA, following the first expedition in 1994. The results show that 137Cs, 90Sr and 239 + 240Pu concentrations in surface and bottom waters at dumping areas do not significantly differ from the values observed in background areas, and from historical values. There is no clear effect of possible contamination due to radioactive waste dumping. The concentrations and water column inventories of 137Cs, 90Sr and 239 + 240Pu in the Far Eastern seas are controlled by physical oceanic processes such as horizontal transport and biogeochemical processes such as scavenging.

Radioactive contamination from dumped nuclear waste in the Kara Sea--results from the joint Russian-Norwegian expeditions in 1992-1994.

Russian-Norwegian expeditions to the Kara Sea and to dumping sites in the fjords of Novaya Zemlya have taken place annually since 1992. In the fjords, dumped objects were localised with sonar and ROV equipped with underwater camera. Enhanced levels of 137Cs, 60Co, 90Sr and 239,240Pu in sediments close to dumped containers in the Abrosimov and Stepovogo fjords demonstrated that leaching from dumped material has taken place. The contamination was inhomogeneously distributed and radioactive particles were identified in the upper 10 cm of the sediments. 137Cs was strongly associated with sediments, while 90Sr was more mobile. The contamination was less pronounced in the areas where objects presumed to be reactor compartments were located. The enhanced level of radionuclides observed in sediments close to the submarine in Stepovogo fjord in 1993 could, however, not be confirmed in 1994. Otherwise, traces of 60Co in sediments were observed in the close vicinity of all localised objects. Thus, the general level of radionuclides in waters, sediments and biota in the fjords is, somewhat higher or similar to that of the open Kara Sea, i.e. significantly lower than in other adjacent marine systems (e.g. Irish Sea, Baltic Sea, North Sea). The main sources contributing to radioactive contamination were global fallout from atmospheric nuclear weapon tests, river transport from Ob and Yenisey, marine transport of discharges from Sellafield, UK and fallout from Chernobyl. Thus, the radiological impact to man and the arctic environment of the observed leakages from dumped radioactive waste today, is considered to be low. Assuming all radionuclides are released from the waste, preliminary assessments indicate a collective dose to the world population of less than 50 man Sv.