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(T/EH019) Dynamics of contamination of the zebra mussel from water, phytoplankton and suspended solids by Am-241. Adam, Christelle1, Garnier-Laplace, Jacqueline1, Baudin, Jean-Pierre2, 1 2 ABSTRACT- The dynamics of contamination of the zebra mussel (Dreissena polymorpha) by 241Am were quantified in a simplified experimental ecosystem. Main sources of contamination were considered : filtered water, phytoplankton and other natural suspended matter collected throughout the seasonal cycle of the Rhone river. The kinetic constants of accumulation and elimination governing each transfer to the zebra mussel were estimated under controlled conditions. They were integrated into a model used to simulate the time series of pollutant concentrations within an autochtonous population of zebra mussels in the Rhone River downstream of the Marcoule fuel reprocessing plant. The model was validated on the basis of a comparison between the simulated results and the data from quarterly gamma spectrometry measurements of samples from the mussel population. The water pathway was predominant for the whole mussel, almost reaching 99 % of total contamination, during spring and winter. This phenomenon may be explained by the high content of 241Am in the shell. The contamination linked to the ingestion of suspended matter was weaker, since it represented from 15 to 50 % of the total contamination during summer and autumn respectively, those seasons being characterized by greater 241Am concentrations in the suspended matter and a more efficient feeding of the bivalves. Key words: mussel, americium, model, field |
