SEASONAL DYNAMICS OF CHEMICAL COMPOSITION OF WATERS FROM GULLY SYSTEMS IN URBAN AREAS (BY THE EXAMPLE OF SARATOV)
The relevance of the research is determined by the need to ensure the environmental well-being of water bodies in the zone of impact of large cities. In accordance with modern environmental, nonconsumptive and urban planning requirements, water runoff from urbanized areas should not have a negative impact on the quality of water resources. The main aim of the research is to determine the seasonal dynamics (spring maximum and summer-autumn minimum flow) of pollutants from the water flow of ravines and gullies from the city of Saratov to the Volgograd reservoir. Methods: morphometric analysis of catchment basins of gully complexes; mapping of tributaries of natural and technogenic origin; testing of waters in estuaries before the confluence with the Volgograd reservoir; chemical analysis of surface water composition by priority indicators according to generally accepted methods (140 definitions in total); assessment and analysis of water quality in relation to standards for water bodies of fishery importance. Results. The author characterized the functioning of urban ravines and gullies; determined the features of formation of chemical composition and transport of water through the erosion network of an urbanized area; defined the composition of the waters of the ten largest ravine-gully complexes for priority pollutants for the Volgograd reservoir (nitrites, iron, copper, zinc, sulfates, ammonium nitrogen, oil products); found concentrations of pollutants, many times exceeding the established standards for fisheries reservoirs in the water flow. The quality of water flow does not meet the standards established for water bodies of fishery importance, which include the Volgograd reservoir as part of the Volga basin. In the seasonal dynamics of the chemical composition of water, unidirectional trends are not detected. Out of 70 comparative pairs of samples of spring and summer-autumn runoff, a decrease in summer concentrations was detected in 41 cases (58,6 %), an increase in 21 (30 %), and no changes in 8 (11,4 %). Flow quality control should be based on the analysis of specific watersheds. Given the fact that the reservoir is as a source of centralized drinking water supply and recreational activities, the organization of surface water treatment systems is necessary.