Bioaccumulation of Heavy Metals in Soft Tissues of Bivalve Mollusks from Natural Lakes in Eastern Sikhote Alin (Russia) and the Mekong Delta (Vietnam)

The concentrations of seven heavy metals (HMs) in tissues of bivalve mollusks of the families Unionidae (genera Ensidens, Scabies , Kunashiria ) and Cyrenidae (genus Corbicula ) and from four natural lakes located on the eastern slope of Sikhote Alin (Primorskii krai, Russian Far East) the Mekong River delta (Vietnam) were determined. It was established that the HM concentrations in the bivalve mollusks studied, inhabiting unpolluted water reservoirs, are specific for every family and do not depend on the geographical positions of the lakes. They decrease in the following order: Mn > Fe > Zn > Cu > Ni > Cd > Pb for Unionidae, and Fe > Zn > Cu > Mn > Ni ≥ Cd > Pb for Cyrenidae ( Corbicula ). It is likely that deviations from the revealed sequence are due to anthropogenic pollution of lakes with some metals or the occurrence of a natural geological anomaly.