摘要
地下水稳定碳同位素可以指示微生物作用下有机质降解过程对砷富集的影响.新疆奎屯地区是中国西北干旱区典型原生高砷水分布区,本研究以地下水为研究对象,奎屯河地表水为对照,通过野外采样,并借助原子荧光、稳定同位素分析等技术手段,对地下水的水化学指标、溶解性无机碳(DIC)、溶解性有机碳(DOC)和碳稳定同位素进行测定与分析.结果表明,研究区73%的地下水为高砷水,平均值为60.60μg·L^(-1),呈还原-弱碱性环境,地表水均为低砷水,呈中性和氧化环境.地下水中优势阴阳离子分别为Cl^(-)和Ca^(2+).地下水DIC受多种来源的共同影响,地表水DIC主要来自碳酸盐岩风化作用的影响.地下水δ^(13)C_(DIC)值的范围为-9.13‰—0.58‰,δ^(13)CDOC值的范围在-21.62‰—-13.79‰之间.地下水中除了微生物作用下有机质降解和碳酸盐岩溶解的影响外,还可能存在产甲烷过程对δ^(13)C_(DIC)值的影响.地下水中δ^(13)C_(DIC)-δ^(13)CDOC差值与ρ(As)、ρ(Fe)均呈显著负相关关系,表明微生物参与了铁氧化物的还原性溶解并促进了As的富集.
The stable carbon isotope of groundwater can indicate the influence of organic matter degradation process under the action of microorganisms on arsenic enrichment.Kuitun area of Xinjiang is a typical primary high arsenic water distribution area in the arid region of northwest China.In this study,the groundwater was taken as the research object,and the surface water of Kuitun River was taken as the control.The hydrochemical indicators,dissolved inorganic carbon(DIC),dissolved organic carbon(DOC)and carbon stable isotope of the groundwater were determined and analyzed.The results show that 73%of groundwater in the study area was high arsenic water,with an average value of 60.60μg·L^(-1),presenting a reduction-weak alkaline environment,while the surface water was low arsenic water,presenting a neutral and oxidizing environment.The dominant anions in the groundwater were Cl^(-)and Ca^(2+),respectively.The DIC of the groundwater was commonly influenced by various sources,and the DIC of the surface water mainly came from the influence of carbonate weathering.The value ofδ^(13)C_(DIC)ranged from-9.13‰to 0.58‰and the values ofδ^(13)CDOC ranged from-21.62‰to-13.79‰in the groundwater.In addition to the degradation of organic matter and the dissolution of carbonate karst under the action of microorganisms,methanogenesis may also affect theδ^(13)C_(DIC)value in the groundwater.There was a negative correlation betweenδ^(13)C_(DIC)-δ^(13)CDOC and As concentration also betweenδ^(13)C_(DIC)-δ^(13)CDOC and Fe concentration in the groundwater,indicating that microorganisms participated in the reductive dissolution of iron oxides and promoted the enrichment of As.
作者
晁博
罗艳丽
王翔
CHAO Bo;LUO Yanli;WANG Xiang(College of Resource and Environment,Xinjiang Agricultural University,Urumqi,830052,China)
出处
《环境化学》
CAS
CSCD
北大核心
2024年第3期951-960,共10页
Environmental Chemistry
基金
国家自然科学基金(41761097,42067053)资助。
关键词
高砷地下水
稳定碳同位素
溶解性有机碳
溶解性无机碳
high arsenic groundwater
stable carbon isotopes
dissolved organic carbon
dissolved inorganic carbon
