湖南锡矿山高锑地下水稳定碳同位素特征及其富锑意义

Characteristics of Stable Carbon Isotopes and Its Significance of Antimony Enrichment in High-antimony Groundwater of Xikuangshan Mines,Hunan

溶解性有机碳是地下水中Sb富集的关键因素,为探明湖南锡矿山高Sb地下水稳定碳同位素特征,揭示有机质氧化分解过程对地下水中Sb富集的影响,对湖南锡矿山高Sb地下水选用碳稳定同位素分馏和水化学相结合的方式进行分析。结果表明:湖南锡矿山高Sb地下水δ^(13)C_(DIC)值在-17.84‰~-2.30‰,δ^(13)C_(DOC)值在-26.87‰~-16.70‰。高Sb地下水中Sb与DOC、HCO_(3)^(-)均呈正相关关系,表明微生物作用对高Sb地下水中Sb的富集具有较大的贡献。高Sb地下水溶解性有机碳相对于溶解性无机碳具有更负的δ^(13)C值,DOC主要受内源有机质的影响;随着δ^(13)C_(DIC)-δ^(13)C_(DOC)差值的减小,Sb浓度逐渐升高,表明由于微生物的存在,有机质的氧化分解明显促进了高Sb地下水中Sb的富集。

DOC(dissolved organic carbon)is a crucial factor for antimony(Sb)enrichment in groundwater.High-Sb groundwater samples were analyzed using hydrochemistry and stable carbon isotope to elaborate the effects of oxidative degradation of organic matter on Sb enrichment in groundwater of Xikuangshan Mines,Hunan.The results indicate that the value ofδ^(13)C_(DIC) andδ^(13)C_(DOC) ranged from-17.84‰to-2.30‰and from-26.87‰to-16.70‰,respectively.An obviously positive correlation between Sb and DOC,as well as HCO_(3)^(-) in high-Sb groundwater,indicating that Sb enrichment may be significantly contributed to microbial activities.Meanwhile,DOC had lower values ofδ^(13)C compared with dissolved inorganic carbon,suggesting DOC was mainly controlled by endogenous organic matter.Owing to the Sb concentration showed gradually increased trends with decreasing difference betweenδ^(13)C_(DIC) andδ^(13)C_(DOC),the microbial degradation of DOM had a substantial contribution to Sb mobility.