TISSUE DISTRIBUTION OF INORGANIC MERCURY, METHYLMERCURY AND CADMIUM IN THE ASIATIC CLAM (CORBICULA-FLUMINEA) IN RELATION TO THE CONTAMINATION LEVELS OF THE WATER COLUMN AND SEDIMENT

The comparative experimental study of inorganic mercury (HgII), methyl mercury (MeHg) and cadmium (Cd) bioaccumulation in the Asiatic clam Co rbicula fluminea was based on a 14 days' exposure to the water column or sediment compartments, as initial contamination sources. For each c ontaminant and exposure source, a five-point concentration range was s et up in order to quantify the relationships between the contamination pressure and bioaccumulation capacity, at the whole soft body level a nd in five organs: gills, mantle, visceral mass, kidney and foot. Hg a nd Cd bioaccumulation at the whole organism level was proportional to the metal concentrations in the water column or sediment. For similar exposure conditions, the average ratios between the metal concentratio ns in the bivalves - [MeHg]/[HgII] and [MeHg]/[Cd] - were close to 10 and 5 for the sediment source and 8 and 15 for the water column source . Metal distribution in the five organs revealed strong specificities, according to the different contamination modalities studied: kidney a nd gills were clearly associated with Cd exposure, mantle and foot wit h MeHg exposure and the visceral mass with inorganic Hg exposure. (C) 1997 Published by Elsevier Science Ltd.