Determining the factors controlling the chemical composition of groundwater using multivariate statistics and geochemical methods in the Xiqu coal mine, North China

Studying the hydrogeochemical processes that control groundwater quality in different aquifers helps to identify the sources of inrush water into coal mines. In this paper, 65 mine water samples were collected from Xiqu coal mine during 2016 and 2017 to determine the hydrogeochemical processes and controlling factors of mine water using hydrochemical methods and multivariate statistical analysis. The mine water is acidic to alkaline in nature. The dominant anions in the mine water are SO₄²⁻ and HCO₃⁻, and cations were dominated by Ca²⁺ Na⁺, and Mg²⁺. The dominant  hydrochemical facies of groundwater were SO₄–Na·Ca and SO₄–Ca·Mg water types. Based on multivariate statistical analysis, four principal components and two clusters were obtained. Concentrations of SO₄²⁻ showed significant positive correlations with Ca²⁺, Mg²⁺, Fe²⁺ and Fe³⁺, and strong negative correlations with HCO₃⁻ and pH. The mine water chemistry was dominated by the oxidation of iron-bearing sulfide minerals, cation exchange and the dissolution of silicate, carbonate and sulfate minerals. In addition, human activities such as agriculture are also likely to have influences groundwater chemistry at the mine site.