ACCUMULATION OF COPPER, LEAD AND CADMIUM IN FRESH-WATER SNAILS IN SOUTHWESTERN NIGERIA

The accumulation of copper, lead and cadmium in freshwater snails (Bio mphalaria Pfeifferi, Bulinus globosus, Lanistes libicus, Lymnaea natal ensis, Potadoma moerchi, Melanoides tuberculata, Gabiella africana, Pi la ovum and Bellamya species) was analysed in man-made dams and rivers in southwest Nigeria using a flameless atomic absorption spectrophoto meter. Metal concentrations varied widely among snail species and site s. Metal concentrations within the same snail species were strongly co rrelated with other metals within the same snail species. Seasonal cha nges in the metal concentrations occurred in some locations. The highe st concentration of copper (2352 mu g/g) was found in L. natalensis co llected from Owena-Ondo daM in May, lead (52.1 mu g/g) in B. globosus at Esa-Odo dam in July while cadmium (31.6 mu g/g) was recorded in B. globosus sampled at Owena-Jesa dam in April, 1993. The results implica te the use of freshwater snails as a valuable tool for future monitori ng programmes to evaluate the metal burden of man-made dams and rivers in the tropics. Copyright (C) 1996 Elsevier Science B.V.