Hydrogeochemistry characteristic contrasts between low- and high-antimony in shallow drinkable groundwater at the largest antimony mine in hunan province, China

Abstract

The antimony (Sb) content of shallow drinkable groundwater at Xikuangshang mine area (in Hunan province, China) has exceeded China's national drinking water quality guidelines, posing a serious threat to the health of residents in the mine area. The difference in hydrogeochemistry characteristics and water-rock interactions between low Sb groundwater (<0.015 mg/L) and high Sb groundwater (>0.015 mg/L), however, remains unclear. In this study, 24 samples were collected from shallow drinkable groundwater at the mine area. The hydrogeochemistry data and water-rock interactions were analyzed to reveal the condition leading to the formation of high Sb groundwater. Compared with low Sb groundwater, high Sb groundwater has a higher level of Na+, TDS, and SO42-, which increase by 6.38, 1.84, and 4.04 times, respectively. The low Sb groundwater is mainly controlled by Ca–HCO3–SO4 type, whereas the high Sb groundwater is controlled by Ca–HCO3–SO4 type as the main facies, and Ca–Na–SO4 type and Ca–SO4–HCO3 type as the secondary facies. The chemical composition of low Sb groundwater is mainly influenced by the dissolution of carbonate minerals and the chemical composition of high Sb groundwater is controlled by ion-exchange interaction and dissolution of carbonate minerals and silicate minerals, among which ion-exchange interaction is the most important factor. The outcomes of this research provide a better understanding of the mechanisms of Sb pollution in groundwater and it will help in securing safe drinking water sources for local communities.