Radioactive contamination of aquatic ecosystem within the Chernobyl NPP exclusion zone: 15 years after accident

A quatic ecosystems and especially lakes are efficient collectors for the wide range of radionuclides, which are deposited in abiotic and biotic components after their intake by aquatic environments. For the time being, ecosystems of water bodies of the Chernobyl NPP exclusion zone continue to suffer from heavy radioactive contamination. dictating, thus, the need to carry out further research works within the framework of comprehensive regional radioecological monitoring. Particular features of radionuclide accumulation by hydrobionts substantially depend on formation of hydrochemical composition of water, which, in its turn, is a complex process, depending on functioning of aquatic ecosystems and natural conditions of a water catchment basin. Hydrochemical regimes in reservoirs are determined by external factors and internal water body processes. The results of radionuclides Sr-90, Cs-137, Pu-238, Pu239+240 and Am-241 content in hydrobionts tissues of different trophic levels of water objects within the Chernobyl NPP exclusion zone have been analysed. Our studies were conducted: (1) to identify dynamics of radionuclide distribution in components of freshwater biocenose of water bodies within the Chernobyl NPP exclusion zone: (2) to study dynamic profiles of radioactive contamination levels in species of different ecological groups; (3) to assess the major factors, which determine distribution of radionuclides in the freshwater ecosystems, (4) to study the seasonal dynamics of radionuclides content in macrophites and the role of main aquatic plant associations in processes of radionuclides distribution in biotic component of biohydrocenose; (5) to assess a possibility to use hydrobionts of different trophic levels as biological indicators of radioactive contamination of water objects and (6) to assess the absorbed dose rate for hydrobionts from different water bodies.