Antimony (Sb) isotopic signature in water systems from the world's largest Sb mine, central China: Novel insights to trace Sb source and mobilization.

The Xikuangshan (XKS) mine, the world's largest antimony (Sb) mine, was chosen for a detailed Sb isotopic signature study owing to its historical Sb contamination of water systems. Hydrochemical data, in particularδ123Sb values, were analyzed to identify the Sb source and predominant geochemical processes that affect Sb mobilization in different waters. The δ123Sb values of waters from the XKS Sb mine range from - 0.20‰ to + 0.73‰. In particular, the δ123Sb values of the main Feishuiyan stream do not significantly vary (+0.19‰-+0.24‰), while those of groundwater in different aquifers (-0.08‰ to +0.73‰) and mine water in different adits (-0.20‰ to +0.37‰) vary over a wide range. The relationships between δ123Sb values and Sb concentrations indicate that a simple dilution of Sb and a weak Sb adsorption onto Fe/Mn suspended particles and sediments in the Feishuiyan stream may occur, oxidative weathering and leaching infiltration of Sb-containing waste rocks and slags may cause variations in the δ123Sb values in groundwater, and Sb mobilization in the mine water is influenced by a combination of processes (oxidative dissolution, adsorption of Fe/Mn (hydr)oxides, and mixing). A conceptual hydrogeochemical model was summarized to elucidate the Sb source and mobilization in water systems from the XKS Sb mine.