HYDROCHEMICAL SITUATION IN THE TSIMLYANSK RESERVOIR ACCORDING TO THE RESULTS OF OBSERVATIONS IN 2011-2018

Tsimlyansk Reservoir is the largest reservoir of the Rostov region and southern Russia. The main factors for the formation of the hydrochemical regime of the Tsimlyansk Reservoir are the chemical composition of the water entering the river runoff and its mixing with the water accumulated in the reservoir. The chemical composition of the surface waters of the Don River basin is characterized by great diversity, which is associated with anthropogenic factors and the difference in the physiographic conditions in which the formation of surface waters takes place. The main sources of pollution of the Don River surface waters are wastewater enterprises of housing and communal services, chemical, petrochemical, metallurgical, agricultural and other industries, shipping and small fleet. The catchment area of the Don is located in the zone of insufficient moisture, which explains the cause of low-flow. The environmental situation in the Don basin, and especially on the Lower Don, is characterized as stressful, and when low-flow years and periods occur in the basin, there may be water shortages that manifest themselves not only in the lack of water of the required quality to meet the needs of the population and economy, but also in the impossibility preservation of necessary conditions for the existence of aquatic and riparian ecosystems. In this regard, the complex study of the hydrological and hydrochemical and hydrobiological conditions in the Tsimlyansk reservoir is becoming increasingly important. The purpose of the research was to study the current hydrochemical state of the Tsimlyansk reservoir, assess the dynamics of changes in the hydrochemical situation in the water column over the period from November 2011 to September 2018, and indirectly estimate the productivity of the Tsimlyansky reservoir water by chlorophyll "a". The published data were analyzed and compared with the results of our own research. The values of the N: P ratio during the observation period, in most cases, indicated the limitation of the primary production by nitrogen. The long-term dynamics of the content of the determined parameters under different water conditions did not have pronounced tendencies; in general, the concentrations of nutrients in all field research are comparable, subject to seasonal fluctuations, are in accordance with natural mechanisms and under anthropogenic influence.

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