Accumulation of copper, lead and cadmium in freshwater snails in southwestern Nigeria

The accumulation of copper, lead and cadmium in freshwater snails (Biomphalaria pfeifferi, Bulinus globosus, Lanistes libicus, Lymnaea natalensis, Potadoma moerchi, Melanoides tuberculata, Gabiella africana, Pila ovum and Bellamya species) was analysed in man-made dams and rivers in southwest Nigeria using a flameless atomic absorption spectrophotometer. Metal concentrations varied widely among snail species and sites. Metal concentrations within the same snail species were strongly correlated with other metals within the same snail species. Seasonal changes in the metal concentrations occurred in some locations. The highest concentration of copper (2352 μg/g) was found in L. natalensis collected from Owena-Ondo daM in May, lead (52.1 μg/g) in B. globosus at Esa-Odo dam in July while cadmium (31.6 μg/g) was recorded in B. globosus sampled at Owena-Jesa dam in April, 1993. The results implicate the use of freshwater snails as a valuable tool for future monitoring programmes to evaluate the metal burden of man-made dams and rivers in the tropics.