好氧黑暗地下水环境中Sb（III）也能实现快速氧化，前人推断Fe（Ⅱ）和Sb（Ⅲ）共氧化可能是最重要的驱动机制，然而该机制缺乏环境同位素分馏的野外验证。为此，野外采集湖南锡矿山锑矿区北矿水高低Sb地下水样品20组，通过对比高低Sb地下水环境同位素（δ⁵⁶Fe、δ¹³ C和δ³⁴S）的差异，探究高Sb地下水形成过程中环境同位素的分馏过程，揭示好氧黑暗地下水环境中Sb（Ⅲ）快速氧化的新机制。结果表明：湖南锡矿山锑矿区北矿水中总锑（^TSb）浓度范围为5.30 ~ 20 700 μg/L，平均值为3 660.61 μg/L, Sb（Ⅴ）是最主要的Sb价态。偏中性-弱碱性和富含氧气的水环境为FeS₂和Sb₂ S₃共氧化提供了便利，也引发了沉积物和地下水间δ¹⁸O_SO4、δ³⁴ S_SO4和δ⁵⁶ Fe的分馏，导致高Sb地下水、总铁（^TFe）和Sb（Ⅴ）含量的升高。与此同时，微生物活动导致的有机碳氧化分解进一步促进了Fe（Ⅱ）和Sb（Ⅲ）共氧化速率的提升。该结论揭示了好氧黑暗地下水环境中Sb（Ⅲ）氧化新机制，并为进一步提升Sb地球化学循环过程的认知和防止高Sb地下水污染提供科学依据。

The oxidation of Sb(Ⅲ) occurred rapidly in aerobic and dark groundwater environments, with previous studies suggesting that co-oxidation of Fe(Ⅱ) and Sb(Ⅲ) may be the predominant driving mechanism. However, there is a lack of field evidence confirming environmental isotope fractionation. Therefore, 20 groups of Magunao aquifer (water) samples were collected from the North mine of Xikuangshan antimony mining area in Hunan Province to compare the differences in environmental isotopes (δ⁵⁶ Fe,δ¹³ C, and δ³⁴ S) between high- and low-Sb groundwater and investigate the fractionation process of these isotopes. The results reveal that total Sb(^TSb) concentrations ranged from 5.30 μg/L to 20 700 μg/L, with a mean concentration of 3 660.61 μg/L. Additionally, Sb(V) is found to be the most dominant valence state for Sb in water. The neutral-alkaline and oxygen-enriched conditions in water facilitate the co-oxidation of FeS₂ and Sb₂ S₃, as well as induce fractionation of δ¹⁸ O_SO4, δ³⁴S_SO4 and δ⁵⁶Fe between sediments and groundwater, resulting in the increase of , total Fe (^TFe) and Sb(Ⅴ) contents in high Sb groundwater. Furthermore, microbial activities promote the oxidative decomposition of organic carbon, thereby enhancing the co-oxidation rate of Fe(Ⅱ) and Sb(Ⅲ). This conclusion unveils a novel mechanism for aerobic oxidation of Sb(Ⅲ) in dark groundwater environments while providing a scientific foundation for advancing our understanding of the Sb geochemical cycle and preventing environmental pollution from high Sb groundwater.