Anthropogenic Load and Variability of the Pollutant Content in the Water of Podkumok, a Nonglacial River in the Central Caucasus, over a Long-Term Period (2005‒2019)

The pollution level of the Podkumok, a nonglacial river in Central Caucasus, was assessed by comparison with the established maximum permissible concentrations of ecotoxicants NO2‒, NO3‒, and NH4+ for a fifteen-year observation period; the quality class of the surface water was determined. The results of chemical analysis of the concentration levels of pollutants in the Podkumok River watercourse were used. Certain biogenic nitrogen compounds are currently equated to a number of heavy metals in terms of the negative impact they exert on aquatic ecosystems. The content of nitrogen compounds was determined using chemical analysis methods. The years of water pollution with all forms of inorganic nitrogen and their repeatability were identified. An environmental assessment of the pollution of the Podkumok River by year in the main phases of the hydrological regime, i.e., during the winter low water and summer flood periods, was provided according to the quality classification system for land surface waters. Based on the observations of the composition of the river waters in the period 2005‒2019, the levels of pollutants in the watercourse of the Podkumok River were identified.