Contrasting water–rock interaction behaviors of antimony and arsenic in contaminated rivers around an antimony mine, Hunan Province, China

Morphological Distribution and Formation Mechanisms of Antimony in the Shallow Groundwater of the Xikuangshan Antimony Mine in Hunan, China

“…HCO 3 − can reduce the effective adsorption sites of the adsorbent through competitive adsorption, thereby affecting the attachment of Sb to minerals. Generally, a high HCO 3 − concentration leads to stronger competitive adsorption; thus, the released Sb(Ⅴ) content increases (Wang et al, 2018;Hao et al, 2021). Figure 6C shows that the Sb content in the runoff area was positively correlated with HCO 3 − (R 2 = 0.53), while there was no obvious correlation between the recharge and the discharge areas.…”

“…Figure 6B shows that the positive correlation between Sb and Cl − in the runoff area, indicating that the influence of anthropogenic activities on the increase of Sb content in the runoff area can not be ignored (Hao et al, 2021). The Sb content exhibited stronger positive correlations with the contents of HCO 3 − , and TDS in the runoff area than in the recharge and discharge areas (Figures 6C,D), indicating that a strong water-rock interaction can promote the dissolution of carbonate minerals and neutralize the H + generated by the dissolution of Sb 2 S 3.…”

“…Some water samples in the recharge and runoff areas were outside the Gibbs diagram, indicating that they may also have been affected by human activities (Thomas et al, 2013). At the same time, the presence of Cl − indicates the influence of anthropogenic activities (Hao et al, 2021).…”

“…Further, calcium, magnesium, and other substances in the soil are replaced through oxidative decomposition under the effects of light, oxygen, plants, and microorganisms. After their release, under the influence of rainwater erosion and surface runoff, they enter the groundwater, and Ca 2+ and Mg 2+ have reverse cation exchanges with K + and Na + in the surrounding rock, which increase the content of K + and Na + in the water (Supplementary Figure S5) (Xing et al, 2013;Liu et al, 2019;Hao et al, 2021). Along the groundwater-flow direction, from the recharge area to the runoff area, the Na + content first increased and then decreased; from the runoff area to the discharge area, the Na + content first increased and then decreased (Figure 3A).…”

“…Owing to rock weathering, mining activities, waste-rock residues, and domestic garbage accumulation in the XKS Sb mining area in Hunan, Sb-containing pollutants would enter the shallow groundwater through rainwater erosion and surface runoff, thereby increasing the Sb(Ⅴ) content in the D 3 x 4 water. Factor 2 (23.88%) was predominantly loaded on Ca 2+ , Mg 2+ , and SO 4 2− , indicating carbonate and silicate mineral dissolutions and cation exchange (Hao et al, 2021). Mineral dissolution controls the chemical composition of water in recharge and discharge areas (Supplementary Figure S7).…”