Peculiarities of Formation of the Chemical Composition of Caucasian Glacier-Fed Rivers During Intensive Degradation of Glaciers

Abstract

The concentration of heavy metals (Cr, Ni, Mo, Mn, Pb, Zn, Ag, Cu, Cd, Co, Al, Fe, V) in one of the most powerful glaciation sites in the Caucasus (Mount Elbrus) since the mid-20th century is investigated. To compare the concentrations of heavy metals in the sources of the Baksan River with those in the Garabashi glacier, a stationary point at a level of 4000 m was chosen, where observations of the glacier mass balance are carried out. The number of pit samples depended on the snow accumulation and varied from 7-8 to 18-20 in accordance with the depth of the seasonal snow layer. The concentrations of heavy metals in the ice, snow, and river water samples were determined during the period from 1978 to 2010 at High-mountain Geophysical Institute by the emission spectral analysis. The analysis of samples from 2018-2021 was performed by the atomic absorption method on an MGA-915 spectrometer. Among all categories of the samples taken on the Elbrus slope, the least impurities were found in pure ice on the tongue of the glacier: it contains three times less impurities of Ag, Ni, Mo, Pb: 0.014, 1.15, 0.18, 0.83 µg/L, respectively. In some samples, the metal content is below the detection limit. The concentrations of heavy metals in the seasonal snow pack and river water in the Elbrus region are one-two orders of magnitude lower than maximum permissible concentrations for sanitary water bodies. For the Baksan River basin and the Elbrus glaciation region, there is a slight decrease in the concentrations of heavy metals from the end of the 20th century until the present, with intensive degradation of glaciers.