Concentration and distribution of 210Po in the tissues of the scallop Chlamys varia and the mussel Mytilus edulis from the coasts of Charente-Maritime (France)

Polonium-210 (Po-210) has been analysed in the soft parts of two bivalves species, the scallop Chlamys varia and the common mussel Mytilus edulis, from the Bay of La Roehelle and Re Island, on the French Atlantic coast. Between those sites, the highest Po-210 concentrations have been found in whole scallop soft parts from La Rochelle, reaching 1181 +/- 29 Bq kg(-1) dry weight (dwt), a size effect being related to the highest Po-210 concentration in the smallest scallops. The results show a significant difference in concentrations for similar size individuals between species in each site (C. varia > M. edulis) and between sites for each species (Re Island > Bay of La Rochelle). Very high Po-210 concentrations have been found in the digestive gland of C. raria, ranging 3150-4637 Bq kg(-1) dwt. Thus, the digestive gland contains up to 60% of the radionuclide. Subcellular investigations have shown that approximately 40% of the Po-210 contained in the digestive gland is in the cytosolic fraction, suggesting a high bioavailability of the Po-210 from this fraction to the trophic upper level. Calculations will show that approximately 4 kg of scallops flesh intake would be necessary to reach the annual incorporation limit of 1 mSv. (C) 2002 Elsevier Science Ltd. All rights reserved.