AGE-DEPENDENT ACCUMULATION OF HEAVY-METALS IN BAIKAL SEAL (PHOCA-SIBIRICA) FROM THE LAKE BAIKAL

Concentrations of Fe, Mn, Zn, Cu, Cd, and Hg were determined in the li ver, kidney, and muscle of 60 Baikal seals collected from Lake Baikal in 1992 to investigate age-dependent accumulation. Among essential ele ments, Fe concentrations in the muscle, liver, and kidney increased wi th age, suggesting development of diving ability. The concentrations o f Mn, Zn, and Cu decreased with age, especially at immature stages. To xic elements such as Hg and Cd decreased in adult males and thus the m ale-female difference was clearly observed in their concentrations, wh ich differed from patterns usually found in marine mammals. Such accum ulation patterns were due to difference in the feeding rates between m ales and females under low exposure to Hg and Cd. In addition, a great er excretion of Hg than that of Cd through molting and parturition was estimated.