ZONAL FEATURES OF THE RYBINSK RESERVOIR BASIN SMALL RIVERS CHEMICAL COMPOSITION

The work is devoted to the study of the chemical composition of small rivers in the southwestern part of the territory of the Vologda region, which form the river flow of the Rybinsk reservoir basin. The determination of the chemical composition of water in rivers is carried out by generally accepted methods according to standard procedures. A distinctive feature of the river waters of the studied drainage basin is their significant difference in color and color intensity, total iron ion content, and ratio of basic anions. Most of the catchment area of this territory is represented by swamps and numerous lakes, many of them are sources of small and medium length watercourses. A comparative analysis of the ion-salt composition of the waters of rivers shows a certain similarity in the manifestation of the zonal features of the formation of their chemical composition. The composition of the water of the rivers in its salt part is mainly due to the climatic conditions. The waters of the rivers have a hydrocarbonate and sulphate-hydrocarbonate magnesium-calcium composition and relatively low mineralization. Statistical processing of the results of analytical data shows a high correlation in terms of color, permanganate oxidation and chemical oxygen consumption of the investigated water samples. Nutrients represented by the mineral forms of nitrogen and phosphorus in river waters within the studied catchment basin are determined by similar concentrations. A single directivity has been established in the distributions of the contents of heavy metal ions. From the number of heavy metal ions (iron, manganese, aluminum, copper, zinc, nickel, lead, arsenic, chromium, cadmium), which were determined in the analyzed samples, the excess of water quality standards for fishery water bodies was established of by iron and manganese ions. Excess of the established standards of quality of natural waters for other identified ions was not detected.