江汉平原高砷地下水监测场水化学特征及砷富集影响因素分析  

Hydrogeochemistry and Arsenic Contamination of Groundwater in the Monitoring Field,Jianghan Plain

作　　者：段艳华[1,2] 甘义群[1,2] 郭欣欣[1,2] 丁旭峰[1,2] 邓娅敏[1,2] 

机构地区：[1]中国地质大学环境学院,武汉430074 [2]中国地质大学生物地质与环境地质国家重点实验室,武汉430074

出　　处：《地质科技情报》2014年第2期140-147,共8页Geological Science and Technology Information

基　　金：国家自然科学基金项目(40830748;41072179);国家自然科学基金国际重大合作项目(41120124003)

摘　　要：江汉平原高砷地下水的发现引起了广泛的关注,通过对该区高砷地下水监测场39个地下水样品的分析,揭示了高砷地下水的水化学特征。同时,结合沉积物砷含量分析和高砷地下水的垂向分布特征,探讨了地下水中砷富集的影响因素。结果表明,地下水水化学类型主要为HCO3-Ca·Mg型,pH值为中性偏弱碱性,Fe、Mn质量浓度很高。25m深度的监测井水中砷质量浓度最高,对应的沉积物中总砷质量浓度也较高。井水中浓烈的H2S气味,偏负的氧化还原电位,高质量浓度的NH4-N、溶解有机碳(DOC)、HCO-3、S2-与低质量浓度的NO-3、SO2-4均指示该区为典型的富含有机质的还原性地下水环境。该条件下沉积物中有机物质的生物降解作用和铁锰氧化物、铁锰氢氧化物的还原是江汉平原高砷地下水形成的主要原因。High arsenic concentration of groundwater in Jianghan plain has ralseci wlaeiy arrennon lil lt^t.;eIit. years. Thirty nine groundwater samples were taken from the monitoring field in Jianghan Plain. Major compositions, organic matters in the groundwater samples and the total arsenic of the sediments were ana- lyzed to characterize groundwater chemistry and evaluate the controlling factors for arsenic concentration and distribution in Jianghan Plain. Results show that groundwater is mainly HCO3 --Ca ·Mg type, cir- cum-neutral to alkalescent pH with high concentrations of Fe and Mn. High arsenic concentrations of groundwater and sediments are mainly distributed at the depth of 25 In. Negative redox potentials coupled with high concentrations of NH4-N.DOC, HCO3- ,S2- and low concentration of NO;- , SO24- clearly indicate a strongly reducing condition with abundant organic matter in the groundwater aquifers. Microbial degra- dation of organic matter and reductive dissolution of Fe and Mn oxyhydroxides （oxides） are the dominant processes for the release of As from aquifers sediments.

关 键 词：江汉平原 监测场 高砷地下水 还原环境 

分 类 号：P641.3[天文地球—地质矿产勘探]