SEASONAL DYNAMICS OF THE CHEMICAL COMPOSITION OF ATMOSPHERIC PRECIPITATION IN SOUTH-EASTERN KAZAKHSTAN

Abstract

The article presents the results of a long-term analysis of the chemical composition of atmospheric precipitation in the southeastern region of Kazakhstan for the period 2005…2024, based on data from the meteorological stations of Almaty, Aul-4, Yesik, Kapchagai, Mynzhilki, and Tekeli. The study aims to identify the spatiotemporal patterns of the ion composition of precipitation under a combination of urbanized, industrial, and high-mountain landscapes. Annual and seasonal mean concentrations of major cations and anions were calculated, interannual dynamics and total mineralization were analyzed, and a correlation analysis of the ionic structure was performed. It was found that, in most years, the total mineralization of precipitation ranges from 1.06 to 7.13 mg/dm³ at the high-mountain station of Mynzhilki and from 8.37 to 25.9 mg/dm³ in urbanized and industrial areas, forming a 2...4-fold spatial contrast. The ion composition is dominated by Na⁺ (44.0…53.0 % of the total major ion mass), HCO₃⁻ (18.0…28.0 %), and Ca²⁺ (10.0–18.0 %). During the cold season, the concentrations of SO₄²⁻, NO₃⁻, and NH₄⁺ exceed those in the warm season by 40.0…80.0 %, reflecting the influence of the heating period and secondary aerosol formation. Correlation analysis revealed stable relationships of SO₄²⁻–Cl⁻ (r = 0.94), Ca²⁺–HCO₃⁻ (r ≈ 0.87), and SO₄²⁻–NH₄⁺ (r ≈ 0.75), confirming the multifactorial nature of precipitation composition formation and the interaction of natural and anthropogenic factors.