PRELIMINARY-RESULTS OF ECOLOGICAL AND GEO CHEMICAL INVESTIGATIONS OF THE RUSSIAN ARCTIC SEAS - (DATA OBTAINED FROM CRUISE-22 OF THE R V ACADEMIK BORIS-PETROV)/

The results of geochemical and radiogeochemical studies carried out Se ptember-October 1995 in the Kara, White, Barents, North, Norwegian, an d Baltic seas are presented. Studies of the distribution of cesium rad ionuclides were carried out along with a hydrogeochemical investigatio n of the natural background using data from samples of sediments and s ea water collected at 92 stations in the Kara Sea. The behavior of ces ium radionuclides in a shallow sea receiving a vast amount of fluvial waters is determined by physical processes (hydrodynamic activity) and sea-floor geomorphology, as well as by geological-geochemical peculia rities of the sea-floor sediments related to processes occurring at th e mouths of large rivers. The relation of Cs-137 migration to litholog y and the reduction-oxidation regime in the sediments, quantity and qu ality of organic matter, salt composition of pore waters, and biogeoch emical processes was studied on the basis of numerous natural samples. The fraction of Chernobyl radiocesium in the total sea-water radioact ivity was estimated using the ratio of two radionuclides with similar behaviors in a marine environment. The results prove the importance of integrated geochemical investigations in the northern seas in estimat ing ecological conditions of the basins of the Arctic regions.