Bioavailability and Ecotoxicity of Metals in Aquatic Systems: Critical Contamination Levels

Bioavailability and ecotoxicity of metals and their relation to geochemical conditions in aquatic environments were considered. It was shown that free ions are the most penetrative species of most metals, except for organometallic complexes of some metals, for example, mercury. We analyzed models for the assessment of the hazard of metal contamination of water environments using the results of thermodynamic calculations of free ion concentrations, the ability of biological receptors to bind them, and the toxic properties of the metals. A concept was developed on the main mechanisms of metal penetration and excretion and cytotoxicity of nonessential elements. A new method was proposed for the estimation of critical levels of polymetallic contamination of water on the basis of measurements of water complexation capacity and determination of the dose–effect relations between the integrated characteristics of the polymetallic contamination and indicators of the health of the ecosystems (in situ) from the results of investigations in the northern Kola Peninsula.