摘要
山西运城盆地是干旱半干旱地区,是我国典型的高砷高氟地下水污染区。在对运城盆地七级镇高砷地下水分布区地下水和钻孔沉积物开展地球化学特征研究的基础上,分析了地下水中砷的物质来源以及控制高砷地下水形成的地球化学过程。结果表明:研究区沉积物的主要矿物成分为硅酸盐、碳酸盐矿物以及少量铁氧化物和黄铁矿等,沉积物中砷的赋存形态主要为碳酸盐结合态/吸附态和Fe-Mn氧化物结合态,是地下水中砷富集的主要物源;研究区地下水中有机物含量较低,微生物活动较弱,属于典型的氧化性弱碱性高砷地下水,在此环境中沉积物中微量黄铁矿的氧化性溶解成为地下水中砷的主要物源,此外由于碳酸盐和硅酸盐矿物的风化和水解作用使地下水中富集大量HCO^-_3,故地下水水化学类型多为HCO_3-Na型,而地下水的弱碱性环境和较高浓度的HCO^-_3会通过竞争性吸附导致沉积物中吸附态砷的溶解或解吸附,促进了地下水中砷的富集。
As an arid/semi-arid district, the Yuncheng basin is a typical contaminated area where groundwa- ter is characterized by high concentrations of arsenic and fluorine. This studg mainly focuses on analyzing the genesis of arsenic and hydrochemical processes that affects the formation of high-arsenic groundwater, based on the hydrogeochemcial characteristics of groundwater and bore-drilling sediments in high-arsenic groundwater area in Qiji County, Yuncheng basin. Research shows that the groundwater in Qiji County contains large numbers of silicate,carbonate,a few iron-including oxide and pyrites. The formation of arse- nic is dominated by carbonate-bound/adsorption and FeMnO-bound （iron and manganese oxides）, which are the major sources of arsenic in groundwater. The groundwater in the study area belongs to typical oxi- dative, weak alkaline, and high arsenic water. The enrichment of HCO^- owing to the wreathing of carbon- ate and silicate, the hydrochemieal type of groundwater is HCO3-Na. The hydrolyzation of silicate makes contribution to the weak alkalinity in groundwater,and lowers the capacity of clay mineral adsorbing arse- nic. Alkalinity and appropriate concentration of HCOa can promote the dissolution of clay mineral-adsorbed arsenic ,further to result in the enrichment of arsenic in groundwater.
出处
《安全与环境工程》
CAS
2017年第5期68-74,共7页
Safety and Environmental Engineering
基金
国家自然科学基金项目(41521001
41372251)
高等学校博士学科点专项科研基金项目(20130145120014)
湖北省自然科学基金项目(2013CFB410)
关键词
高砷地下水
沉积物
地球化学过程
水-岩相互作用
氧化性溶解
运城盆地
arsenic polluted groundwater
sediment
geochemical processes
water-rock interaction
oxidative dissolution
Yuncheng Basin
