Effects of cadmium in freshwater clams. I. Interaction with essential elements inAnodonta cygnea

The elemental composition of the freshwater clam,Anodonta cygnea, was investigated in response to exposure to cadmium at 50 ppb (μg/L) Cd during 12 weeks. Accumulation of cadmium affected the composition in various tissues and hemolymph. From 2 to 8 weeks of exposure considerable loss of sodium occurred, to about half the levels in control animals. During the last four weeks of exposure, sodium concentrations stabilized at the decreased level while those of potassium started to decline. Minor changes were noticeable for other elements. Calcium and iron tended to increase in all organs examined while magnesium levels remained constant. Zinc increased slightly during exposure to cadmium. For some elements, especially zinc and sulphur, hemolymph concentrations showed a response opposite to those in tissues. Concentrations of Al, B, Ba, Be, Ce, Co, Cr, Cu, Li, Mn, Mo, Ni, P, Pb, Sn, Sr, Ti, V, Y, and Zr did not change during Cd exposure. Possible sites of cadmium interaction with ionic regulation are discussed.