Iron in Natural Surface Waters of Ukraine: Content, Peculiarities of Migration and Biological Role

Abstract

Results of long-term investigations of the content of iron in surface water bodies of various types, including the reservoirs of the Dnieper cascade, the Danube River (the Kiliya delta), the Desna River, rivers of the Pripyat, Southern Bug, Ros, Gorny Tikich, and Seret basins, the reservoirs formed on these rivers, some Shatsk lakes, and water bodies located within the territory of Kiev, are given in the paper. The occurrence of this metal mainly in the composition of suspended matter (61.4-97.3% Fetotal) is typical to river waters. In the branches of the Kiliya delta of the Danube River, iron migrates mainly in suspended form, which is conditioned by a high content of mineral suspended matter. A predominance of iron suspended form is observed in some small water bodies of Kiev, which is conditioned by intensive development of phytoplankton. In the reservoirs of the Dnieper cascade, iron occurs mainly in the dissolved form, which is conditioned by its binding into the complexes with organic matter. The degree of iron complexation in the studied water bodies accounts for 89-97% Fedis. In surface waters with high coloration (rivers of the Pripyat basin and the upper reservoirs of the Dnieper cascade), humic substances are of crucial importance in binding iron. In small water bodies, a significant portion of Fedis was found in the composition of neutral complexes with carbohydrates. Results of the study of molecular-mass distribution of anionic and neutral complex compounds of iron are discussed in the paper.