Radioactivity in marine organisms from northeast Atlantic ocean

Naturally-occurring radionuclides such as U-238, U-234, Th-230, Ra-226, Po-210, Pb-210 and Th-232, and artificial radionuclides such as Cs-137, Pu239+240 and Am-241, were measured in a large number of marine species. In common fish species, typical concentrations of 210 ranged from 102 to 104 mBq kg(-1) (wet weight), Ra-226 concentrations ranged from 1 x 10(2) to 5x 10(2) mBq kg(-1), U-238 was at about 10 mBq kg(-1) and Tb-232 at about 10 mBq kg(-1). Radiation doses to marine organisms originated by naturally-occurting and artificial radionuclides accumulated in tissues and by external radiation sources were computed and compared. Internal sources generally give higher contribution to the absorbed radiation dose than external sources. Amongst radionuclides accumulated in fish muscle and acting as internal radiation sources, natural Po-210 and K-40 the largest contribution to the absorbed radiation dose, while artificial radionuclides such as Cs-137 and Pu239+240 contribute with less than 0.5% to the absorbed radiation dose from all internal sources.