Environmental Studies POLONIUM, URANIUM AND PLUTONIUM BIOACCUMULATION IN MARINE BIRDS D.I. Strumińska-Parulska1, B. Skwarzec1, A. Boryło1, J. Fabisiak2 [email protected] University of Gdańsk, Faculty of Chemistry, Analytics and Radiochemistry Chair, Sobieskiego 18/19. 80-952 Gdańsk, Poland 2Naval Academy, Śniadeckiego 61, 81-103 Gdynia, Poland The estimation of the size of contamination caused by alpha radioactive elements in the natural environment and their effects on living organisms is one of the most important issues of the radiochemical and radiological protection. Among alpha radionuclides polonium, uranium and plutonium play an important roles because of their strong accumulation in the marine biota and they are an important sources of radiation dose in the body of marine animals. Birds are double-environment animals and they are an important part of the ecosystems. Seabirds are a very important element of the trophic chain of marine ecosystem. Particularly the birds' feathers are often used as a bioindicator of metal and radionuclide contamination of marine and air environment. In our study 11 marine birds species were examined: 3 species of permanently residing at southern Baltic, 4 species of wintering birds and 3 species of migrating birds. The results showed that polonium, uranium and plutonium are non-uniformly distributed in analyzed seabirds. Among all analyzed radionuclides the highest concentrations were noticed in feathers and viscera and the lowest in skin. Further experiments provided, polonium, uranium and plutonium are mostly adsorbed on feathers not built in. About 63% of polonium, 63-67% of uranium and 82% of plutonium are apparently adsorbed suggesting the external sources such as air or water. The bioaccumulation levels of polonium, uranium and plutonium depend not only on their concentrations in the food but also their concentration in the natural environment. Seabirds are typical double-environment (land-aquatic) animals and radionuclides can come from water and air. That is why seabirds feathers can be good radiological biomonitoring indicator and the isotopic composition of adsorbed radionuclides reflects environment pollution. Acknowledgments: The authors would like to thank the Polish Ministry of Higher Education and Sciences for the financial support of this work under grant: DS/8460-4-0176-1. 109 .