Variations of 210Po and 210Pb in various marine organisms from Western English Channel: contribution of 210Po to the radiation dose

Measurements of 210Po were carried out in various marine matrices (mussels, oysters, seaweed, fish, and abalones) and in seawater at several points along the French coast, over a period of 2 years (2003–2005). These measurements contribute to a better knowledge of this element, since few recent data exist for the French coast. Marked seasonal variations have been revealed in some species and there are differences according to the way of life of these species. Activities in mussels (Mytilus edulis) and oysters (Crassostrea gigas) are similar and varying between 90 and 600 Bq kg−1 (d.w.). Activities in macroalgae (Fucus serratus) are lowest, between 4 and 16 Bq kg−1 (d.w.). In oyster, abalone (Haliotis tuberculata) and fish (Solea solea, Sparus sp.), the strongest activities are measured in the digestive glands, the gills and the gonads. 210Po/210Pb ratios in all cases have values of more than one for all species. From a significant number of measurements, CFs were calculated for seaweed (between 4.6 × 103 and 5.0 × 103) and for molluscs, with highest CFs (>105) found for the digestive gland and gills of the oysters, the digestive gland of the abalones and the liver of fish. Finally, the activities measured have made it possible to estimate the internal dose from chronic exposure due to 210Po received by the marine organisms (0.05 μG h−1 for macroalgae, between 0.70 and 1.5 μG h−1 for mussels and oyster), and the contribution of seafood to the dose received by humans (46–129 μSv y−1).