Аннотация:The interaction of organic matter with metal ions plays a key role in the migration of metals inaquatic ecosystems, the formation of natural water quality and toxicity, and the bioavailability of metals. Sunlight irradiation of swamp and river waters transforms dissolved organic matter, degrading it to low-molecular-weight compounds up to mineralization and simultaneously coagulating compounds of more than 0.22 μm. As a result of the changes in the oxidation state of Fe and its bonds with organic matter the formation of Fe(III) hydroxides occurs. These hydroxides can form large organo-mineral compounds of more than 0.22 μm stabilized by organic ligands, with which Mn, Co, and Cd can coprecipitate.