Abstract
In this study, the major chemical compositions of 159 shallow groundwater samples incorporated saturation index (SI) and Principal Component Analysis (PCA) were employed to evaluate the mainly geochemical processes that control the hydrogeochemical evolution of groundwater in a typical karst area, Bijie city, Guizhou Province. The groundwater samples in this study area were dominated of HCO3-Ca, HCO3-Ca-Mg, and HCO3-SO4-Ca types. The PCA suggested that four principal components could explain 88.85% of the total variance of 10 parameters, indicating that the hydrogeochemical evolution of groundwater was mainly controlled by the dissolution/precipitation of carbonates, gypsum, and halite minerals, cation exchange, and anthropogenic activities. To be specific, the enrichment of Ca2+, Mg2+, HCO3− and SO42− in groundwater were primarily affected by the dissolution of dolomite and gypsum minerals, and the role of calcite dissolution was relatively weaker because most groundwater samples were saturated with respect to calcite. Besides, cation exchange was another factor that may affect the concentration of Ca2+ and Mg2+ in groundwater, and the concentration of SO42− can also be influenced by coal mining activity. In addition, the concentrations of Na+ and Cl− in groundwater were likely influenced by the dissolution of halite, cation exchange, and human activities.
Highlights
Southwest China is a typical karst area with a population of about100 million
total hardness (TH) and total dissolved solid (TDS) are important parameters to evaluate the quality of drinking water [38]
These results suggested that Ca2+, Mg2+, HCO3 − and SO4 2− were the dominant ions in this region
Summary
Southwest China is a typical karst area (covers about 620,000 km2 ) with a population of about100 million. The hydrogeochemical evolution of groundwater is typically affected by natural factors including the composition of rain water, geological structure and mineralogy of aquifer, and water-rock interaction along the flow paths [2,3,4,5,6]. In addition to natural processes, anthropogenic activities can strongly influence the hydrogeochemical characteristic of groundwater [4,5,7,8,9,10]. In light of sustainable management of groundwater resources and scientifically challenging in complex karst settings, understanding the dominant processes that govern groundwater hydrogeochemical evolution is critically needed. Previous studies have shown that the spatial variations of major ion concentrations and stable isotopic composition in groundwater are effectively used to determine groundwater recharge and flow path, source of solutes, interaction between groundwater and aquifer minerals, and the transport of
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