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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. [Display omitted] • The δ123Sb values of waters from the XKS Sb mine range from − 0.2‰ to + 0.73‰. • Both adsorption onto Fe/Mn (hydr)oxides and mixing occur in mine water. • The source and mobilization of Sb are closely related to the mining activities. • A conceptual model of Sb source and mobilization in water systems was proposed. [ABSTRACT FROM AUTHOR]

In this study, a new purification procedure for high precision Sb isotopic analysis was developed by using a thiol silica gel column and is applied to determine Sb isotope composition in natural water samples affected by mining activities. In our proposed procedure, Sb(V) was firstly pre-reduced with 0.5% (w/v) KI–ascorbic acid mixed solution and then Sb(III) in the solution could be separated and purified simply by elution with hydrochloric acid. With the developed procedure, the recovery of antimony was greater than 95.2% and blank values were <0.1 ng. An Apex Ω desolvating sample introduction system was used to improve the sensitivity during Sb isotopic measurement by MC-ICP-MS, and the instrumental mass discrimination was corrected using the sample–standard bracketing (SSB) method combined with the In doping technique. Isobaric effects, matrix effects, and concentration effects were all investigated in detail. 123Sb/121Sb ratios could be measured with a precision of 0.04‰ (2SD). To verify the reliability of the new method, both matrix containing mixed interference elements and a simulated matrix prepared by Sb standard reference material BHVO-2 doping with Spex Sb standard solution were determined. No measurable Sb isotope fractionation was observed with the developed thiol silica gel column procedure. Finally, natural water samples collected from Lengshuijiang were analysed, and significant Sb isotope variations (−0.20 to 0.27‰) were observed, which suggests that Sb isotopes may provide a promising tool to study antimony migration and pollution. [ABSTRACT FROM AUTHOR]