Hydrochemical Characteristics of Natural Waters in the Uppercourse of the Kuban River

A full-scale survey of water bodies differing in origin and formation conditions was conducted in the upper reaches of the Kuban River and the basin of its main tributary, the Teberda River (about 90 observation points). The purpose was to determine typical and atypical levels of a wide range of impurities in water, to identify the real sources of impurities entering watercourses, their migration, spatial distribution of water bodies with increased concentrations, and possible associations of ingredients. Concentrations of major ions (Ca, Mg, Na, K, HCO, SO, Cl) and ions of trace elements (F, Li, Sr) were determined by capillary ionophoresis, trace elements (Al, As, Cr, Cu, Mn, Mo, Ni, Pb, Zn), by atomic absorption method with electrothermal atomization. Based on the data analysis by methods of order statistics, i.e. five-number summary with adding internal and external upper adjacent values, regional elevated, high and extremely high concentrations were distinguished and the distribution of relevant water bodies in the studied area using GIS was revealed. Spatial analysis has shown that in most cases, but not always, they coincide in location with ore occurrences and scattering plumes (As, Mo), zones of modern volcanism under the western peak of Elbrus (Al, Li, F, Mg, SO), of pyritization (SO), zones with prevalence of sedimentary carbonate and gypsum-bearing rocks (Ca, Mg, Sr, SO). In most of the water bodies (50-75%) the concentrations of almost all components are below the river water clarks. They are so depleted of essential elements (F, Ca, Mg, K) that they do not meet the criteria of physiological usefulness for drinking water. Due to the large number of Cu-Zn and Pb-Zn deposits, manifestations and mineralization points, Zn concentrations in 80% of the observation points are higher than clark. In some water bodies, natural pollution of As, Al and Li reaches dangerous levels exceeding MPC of drinking water up to 5 times for Li, 8.5 times for Al and 14 for As and habitants and tourists use them for drinking. The risks increase against the background of a deficiency of the main cations inherent in these waters.