Specific features of bioaccumulation of heavy metals in mollusks within the scope of assessment of the environmental state

115 Intense anthropogenic cumulative toxicological pollution of water bodies makes it necessary to develop the conservation measures and, hence, efficient methods for assessment of the surface water quality. Heavy metals (HMs) are the most toxic agents among those polluting water bodies; in addition, HMs are accumulated in the bodies of hydrobionts at concentrations higher than in the surrounding water [1]. Small amounts of HMs are vitally important for the living organisms; however, high HM concentrations produce a toxic effect. The question of HM deficiency and excess in hydrobiont tissues is far from being solved and remains urgent in terms of the assessment of environmental pollution. An adequate response to different HM concentrations in water is characteristic of mollusks [1‐5], which accumulate HMs in their bodies up to the toxic levels causing pathology, malformations, and mutations [4]. In this study, we aimed at determining the specific features of HM accumulation in mollusks, as well as the limiting levels of potentially toxic HMs in various HM medium gradients. We tried to find a parameter indicating the degree of ecotoxicological hazard in a mollusk population, which may be related to the toxic environmental pollution. As a result of our study, the levels of HM accumulation were determined in both normal mollusks and those with malformations developed under the conditions of various HM medium gradients. Accumulation of the most toxic microelements was found to depend on the ratio of the macroelement concentration in tissues to that in the aquatic medium. The environmental state can be assessed from the parameter of ecotoxicological hazard for the indicator mollusks. The materials were obtained during the Interna