Lazorenko G. Naturally occurring radionuclide polonium-210 in a components of the Black Sea ecosystem: concentrations, distribution and the radiation doses

Radioecological and radiobiological researches on 210Po behavior in the Black Sea ecosystem using system approaches conducted in Ukraine discovered general regularities of its spаtial distribution in the abiotic components of the Black Sea, calculated it's flows from the surface to the bottom of the sea, as well as, established it's additional sources for the reservoir, which gives an opportunity to use this radionuclide as a natural indicator of biosedimentational, biogeochemical and hydroecological processes in this sea. Food chain was first found as the main source of this natural radionuclide for pelagic fish during study of 210Ро in the Black Sea biota, based on measurements of mezo- and macroplankton with consideration of their food chains in plankton group and trophic-parasitic relations in іchtyocenosis of the Black Sea sprat. The relation was found between accumulation of 210Ро by molluscs and their stage of gametogenesis, sex, type of food consumption, ecological state and environment. Indicator abilities of 210Ро were detected in relation to determination of ecological state of Black Sea macrophytes and their life condition. The Black Sea hydrobionts doses of irradiation were calculated depending on 210Ро accumulated by them and estimated their correspondence with IAEA recommendations on safe levels of dose on population of water organisms. Domination of this natural radionuclide in formation of doses was found while comparing dose commitments on indicator species of the Black Sea hydrobionts from 210Ро and from Chernobyl radionuclides. The dose for human population of Ukraine resulting from consumption of marine foodstuffs from sprat as the most massive fish in the Black Sea was calculated. They are smaller in one order of magnitudes than boundary levels of dose, approved by international standards of IAEA and ICRP. A new scientific direction of study of marine natural radioactivity in the Black Sea - "Marine radioecology and radiobiology of 210Po" - has been grounded for research of biophysical, hydroecological, hydrobiological, biogeochemical and biosedimentational processes in Black Sea.