Hydrochemical Peculiarities of Catastrophic Pollution of the Psel River under Influence of Erosion-Hydrological Processes on the Catchment Area

Abstract

Abstract The strengthening of anthropogenic pressure on the catchments of small and medium-sized rivers of the Central Black Earth region of Russia, associated with significant plowing and an increase in the number of livestock complexes, contributes to an increase in the concentrations of organic substances and nutrients in permanent watercourses. At the same time, the sources of their point discharges are absent. This indicates an increase in diffuse pollution of rivers as a result of erosion-hydrological processes in economically developed catchment areas. The case of the formation of catastrophic pollution of the upstream reaches of the Psel (Psyol) River, which led to the mass death of aquatic organisms at the 25 km section of the river, is discussed. It was found that the reason for this is a catastrophic decrease in waterborne oxygen concentrations, caused by a combination of various active water-erosion processes in the plowed catchment area, related to anomalous rainfall, temperature regime, and hydrodynamic characteristics of this section of the river channel. It is shown that in the absence of measures aimed at soil and water protection on the catchments of small rivers of the Central Black Earth regions, in certain weather-climatic conditions, the diffuse water pollution of watercourses may reach a catastrophic level.