Assessment of the impact of mining enterprises on the water resources of high-mountain basins

Abstract

Introduction. This study addresses the assessment of mining-related impacts on water resources in high-mountain river basins, where stream systems are highly sensitive to drainage inflows, disturbed slopes, waste rock dumps, and seasonal runoff variability. The research focuses on a small high-mountain catchment affected by mining activity and examines how hydrochemical parameters, metal migration, suspended matter, and bottom sediments change along the stream channel. Methods. A field and laboratory approach was applied to several monitoring sites located upstream of the industrial impact zone, near drainage inflows, downstream of the industrial area, and at a more distant downstream section. In situ measurements included pH, electrical conductivity, temperature, dissolved oxygen, redox potential, turbidity, and water discharge. Water samples were analyzed for major ions and metals, while bottom sediments were examined to determine metal accumulation. The obtained data were processed using background-normalized coefficients, concentration factors, integrated pollution indices, correlation analysis, and seasonal comparison of dissolved and suspended transport forms. Results. The results showed a clear increase in mineralization, electrical conductivity, sulfate content, iron, manganese, zinc, and copper downstream of the mining-affected area. The strongest hydrochemical changes were recorded below the industrial site and waste rock influence zone. During low-flow conditions, dissolved components reached their highest concentrations, whereas during high-flow periods the total mass export increased due to higher discharge and enhanced suspended transport. Bottom sediments accumulated Cu, Zn, Pb, Mn, and Fe, confirming their role as a secondary pollution reservoir within the channel system. Conclusions. The study demonstrates that the impact of mining enterprises on high-mountain water bodies is not limited to direct changes in water chemistry but also includes seasonal redistribution of pollutants, suspended transport, and accumulation in bottom sediments. A comprehensive assessment of such basins should combine hydrochemical monitoring, sediment analysis, seasonal runoff evaluation, and spatial interpretation of pollution patterns.