Geochemical evolution and quality assessment of water resources in the Sarcheshmeh copper mine area (Iran) using multivariate statistical techniques

Hydrochemical data were gathered throughout the last 12 years from 57 sampling stations in the drainage basin of the Sarcheshmeh copper mine, Kerman Province, Iran. The mean values of these data for each sampling station were used to evaluate water quality and to determine processes that control water chemistry. Principal component analyses specified the oxidation of sulfide minerals, dissolution of carbonate and sulfate minerals and weathering of silicate minerals as the principal processes responsible for the chemical composition of water in the study area. Q-mode cluster analysis revealed three main water groups. The first group had a Ca-HCO₃–SO₄ composition whereas the second and third groups had Ca–SO₄ and Ca–Mg–SO₄ composition, respectively. The results of this study clearly indicated the role of sulfide minerals oxidation and the buffering processes in the geochemical evolution of water in the Sarcheshmeh area. Due to these processes, extensive changes occurred in the chemical composition of water by passage through the mining area or waste and low-grade dumps, so that the fresh water of the peripheral area of the pit evolved to an acid water rich in sulfate and heavy metals at the outlet of the pit and in the seepages of waste and low-grade dumps.