He Ningjie, Li Shu, Li Xiaoqian, Tang Yaning, Yang Jiaxue, Zhou Jianwei
School of Environment Studies, China University of Geosciences, Wuhan 430074, China.
School of Environment Studies, China University of Geosciences, Wuhan 430074, China; Key Laboratory of Mine Ecological Effects and Systematic Restoration, Ministry of Natural Resources, Beijing 100081, China; State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, Wuhan 430074, China.
J Environ Sci (China). 2025 Jan;147:83-92. doi: 10.1016/j.jes.2023.10.015. Epub 2023 Oct 28.
The environmental threat posed by stibnite is an important geoenvironmental issue of current concern. To better understand stibnite oxidation pathways, aerobic abiotic batch experiments were conducted in aqueous solution with varying δO value at initial neutral pH for different lengths of time (15-300 days). The sulfate oxygen and sulfur isotope compositions as well as concentrations of sulfur and antimony species were determined. The sulfur isotope fractionation factor (ΔS) values decreased from 0.8‰ to -2.1‰ during the first 90 days, and increased to 2.6‰ at the 180 days, indicating the dominated intermediate sulfur species such as SO, S, and HS (g) involved in SbS oxidation processes. The incorporation of O into sulfate derived from O (∼100%) indicated that the dissociated O was only directly adsorbed on the stibnite-S sites in the initial stage (0-90 days). The proportion of O incorporation into sulfate from water (27%-52%) increased in the late stage (90-300 days), which suggested the oxidation mechanism changed to hydroxyl attack on stibnite-S sites promoted by nearby adsorbed O on stibnite-Sb sites. The exchange of oxygen between sulfite and water may also contributed to the increase of water derived O into SO. The new insight of stibnite oxidation pathway contributes to the understanding of sulfide oxidation mechanism and helps to interpret field data.
辉锑矿构成的环境威胁是当前备受关注的一个重要地质环境问题。为了更好地理解辉锑矿的氧化途径，在初始中性pH值且具有不同δO值的水溶液中进行了不同时长（15 - 300天）的好氧非生物批量实验。测定了硫酸根的氧和硫同位素组成以及硫和锑物种的浓度。在最初的90天内，硫同位素分馏因子（ΔS）值从0.8‰降至 -2.1‰，并在180天时升至2.6‰，这表明在辉锑矿氧化过程中涉及诸如SO、S和HS（g）等主要中间硫物种。来自O（约100%）的氧掺入到硫酸根中，表明解离出的O在初始阶段（0 - 90天）仅直接吸附在辉锑矿 - S位点上。后期（90 - 300天），来自水的氧掺入到硫酸根中的比例（27% - 52%）增加，这表明氧化机制转变为附近吸附在辉锑矿 - Sb位点上的O促进的羟基对辉锑矿 - S位点的攻击。亚硫酸根与水之间的氧交换也可能导致来自水的O掺入到SO中增加。辉锑矿氧化途径的新见解有助于理解硫化物氧化机制，并有助于解释现场数据。
