CHANGES IN WATER POLLUTION IN THE KARATAL RIVER DURING GLACIER SHRINKAGE IN THE SHYZHY AND KORA RIVER BASINS

Abstract

This study examines the spatial and seasonal variability of water quality in glacier-fed river systems within the Karatal River basin, located in the north-western sector of the Zhetysu Alatau (Kazakhstan). The investigation focused on the Kora and Shyzhy rivers, which play a key role in forming the hydrological regime of the Karatal River. Fieldwork was carried out in 2025 and included two sampling campaigns (July and September), during which a total of 30 water samples were collected from the upper, middle, and lower river reaches. Hydro chemical analyses identified the presence of major ions, nutrients, and a range of trace elements (Pb, Cd, Zn, Cu, Cr, Mn, Sb, Sr, Se, Ni, Al, Mo). The results indicate that water chemistry in the headwater zones is primarily governed by natural processes, including lithological weathering, interactions between meltwater and glacial–moraine deposits, and atmospheric deposition of aerosols onto snow and ice surfaces. Along the downstream gradient, a dual trend is observed: the reduction of certain constituents due to sorption and sedimentation, alongside localized increases associated with anthropogenic pressures. Measured concentrations of chemical constituents remained within the permissible limits established by the sanitary regulations of the Republic of Kazakhstan. Nevertheless, ongoing glacier retreat may intensify the mobilization of previously accumulated contaminants during periods of enhanced ablation. The findings highlight the importance of integrated monitoring approaches for glacier-fed river systems in order to ensure reliable water quality assessment and to minimize emerging environmental risks.