酸性矿山废水对合山地下水污染的硫氧同位素示踪

Using sulfur and oxygen isotopes of sulfate to track groundwater contamination from coal mine drainage in Heshan

以广西合山煤矿为例,应用硫酸盐硫、氧同位素示踪并量化酸性矿山废水对矿区地下水的污染。合山矿井水表现出高浓度SO2-4和低p H值的酸性矿山废水特征,其硫酸盐硫、氧同位素组成显著富集轻同位素,表明煤矸石中黄铁矿的氧化是其产生的主要机制,反应途径为微生物作用下Fe3＋对Fe S2的氧化。利用硫酸盐硫、氧同位素组成并应用三元混合模型计算,结果表明矿区地下水基本都受到酸性矿山废水的入渗影响,其对地下水硫酸盐的贡献比例为16%~52%。硫酸盐硫、氧同位素能够示踪酸性矿山废水对地下水的影响,是示踪与评价矿山开采活动对地下水污染的有效手段。

Stable sulfur and oxygen isotopes of sulfate were used to trace and quantify groundwater contamination from acid mine drainage（AMD） in the Heshan coal mine area.The mine drainage water is characterized by high SO2-4concentration and low p H value,and the S and O isotopic compositions of dissolved sulfate are enriched in light isotopes.Oxidation of pyrite in the coal gangue is the generation mechanism of AMD,and the dominant reaction pathway is by Fe3 ＋oxidation under microorganisms.The calculation results based on ternary mixing model using S and O isotope composition suggest that the groundwater in the coal mine area has been basically affected by infiltration of AMD,and 16% ~ 52% SO2-4of groundwater is from AMD.Stable sulfur and oxygen isotopes of sulfate is indicated to be a more powerful and sensitive tool to track AMD contamination to groundwater.