Bioaccumulation of mercury in the pelagic food chain of the Lake Baikal.

Mercury (Hg) concentrations were analyzed in the livers of Baikal seals and in plankton, zoobenthos and fish which constitute food items for the seals. Concentrations of Hg in the liver of Baikal seals were up to two orders of magnitude lower than those in seals inhabiting other lakes. The low levels of Hg are due to the low levels of the Hg in the fish from the family Comephoride, which reflect the very low concentrations of Hg in Baikal water. The development stage (pups and adults) and the sex of the seals have significant influence on their hepatic Hg concentrations. The differences between Hg accumulation in adult males, adult females and pups could be attributed to the reproductive cycle of the Baikal seals. In spite of low concentrations, Hg is characterized by high values of the concentration factor (CF) for the livers of for Baikal seals. Biomagnification factors (BMFs) suggest biomagnifications of Hg in the fish-seal trophic link.