The dynamics of mercury and cadmium uptake into different organs of Anodonta cygnea L.

The bioaccumulation of Hg and Cd into various organs of the freshwater mussel Anodonta cygnea was investigated during an 840 h experimental period. Parallel with the metal concentrations the periodicity of activity and the body weight of the animals were also checked.The accumulation of Hg in all of the investigated organs, and that of the Cd into the kidney have two phases, up to 24 h it was non linear, between 24 and 72 h it became linear in most organs up to 840 h, and could be characterized by a regression line. For Hg accumulation the gills while for Cd accumulation the kidney and viscera were exceptions, here saturation was observed after 504 and 672 h, respectively.The speed of Hg and Cd uptake was different in various organs of Anodonta cygnea. Into the kidney the accumulation of Hg was six times faster than that of Cd. As compared to the adductor muscles the Hg and Cd uptake of the kidney was 20 and 10 times faster, respectively.The factor of concentration was in all organs except adductor muscles over 1000, in case of the kidney the rate of bioconcentration for Hg reached nearly 100,000.The dry weight of organs dropped during the metal uptake by 20–60%, but no mortality was observed up to 840 h.In the presence of Hg and Cd the filtering activity of the mussels became reduced as a result of increase of inactive rest periods. Nevertheless, the decrease of activity did not prevent the linear uptake of metals into the animal