城镇化进程中珠江三角洲地区浅层地下水中砷分布特征及成因  

Distribution characteristics and causes of arsenic in shallow groundwater in the Pearl River Delta during urbanization

作　　者：吕晓立 郑跃军[1] 韩占涛 李海军 杨明楠[4] 张若琳[1] 刘丹丹 Lü Xiaoli;ZHENG Yuejun;HAN Zhantao;LI Haijun;YANG Mingnan;ZHANG Ruolin;LIU Dandan(China Institute of Geo-Environmental Monitoring,Beijing 100081,China;Technical Centre for Soil,Agriculture and Rural Ecology and Environment,Ministry of Ecology and Environment,Beijing 100012,China;Hebei Investigation Institute of Hydrogeology and Engineering Geology,Shijiazhuang 050021,China;Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang 050061,China;Center for Hydrogeology and Environmental Geology Survey,China Geological Survey,Baoding 071051,China)

机构地区：[1]中国地质环境监测院,北京100081 [2]生态环境部土壤与农业农村生态环境监管技术中心,北京100012 [3]河北省水文工程地质勘查院,河北石家庄050021 [4]中国地质科学院水文地质环境地质研究所,河北石家庄050061 [5]中国地质调查局水文地质环境地质调查中心,河北保定071051

出　　处：《地学前缘》2022年第3期88-98,共11页Earth Science Frontiers

基　　金：中国地质调查局地质调查项目(DD20221749,DD20190322,DD20190331);国家自然科学基金项目(4207071759,41807213);国家重点研发计划项目(2018YFC1803001)。

摘　　要：随着经济的快速发展,城镇化和工业化成为影响地下水环境的重要因素。沿海城市化地区地下水中砷来源复杂,不仅有各种人为来源,天然沉积环境更是造成高砷地下水的主要成因。本文通过对比珠江三角洲地区不同历史时期水化学组分变化,采用离子比和主成分分析技术,研究了城镇化背景下研究区不同类型含水层地下水中砷的分布特征及成因。结果表明,研究区浅层地下水砷浓度介于未检出至420μg·L^(-1)之间,主要以As(Ⅲ)的形态存在,孔隙含水层的砷浓度普遍高于裂隙和岩溶含水层。取自研究区的1567组地下水化学样品测试结果显示,ρ(As)>10μg·L^(-1)的高砷地下水样品检出89组,占比5.7%。其中,孔隙、裂隙和岩溶含水层高砷地下水分别检出82组、4组和3组,占比分别为7.8%、0.8%和9.7%。高砷地下水主要分布在城镇化地区,其比例为非城市化地区的5倍以上。对比历史水化学数据,近10年新增城镇建设用地浅层高砷地下水中砷浓度平均值增加了30%。高砷地下水通常具有pH值较高、氧化还原电位(Eh)较低等特性。地下水中砷浓度与NH_(4)^(+)、Fe、Mn浓度及耗氧量呈正相关。三角洲平原区第四系基底富含有机质的淤泥质沉积地层,在微生物降解和有机质矿化作用下,固着砷的铁(氧)氢氧化物被还原溶解促使砷释放富集。城镇化过程中含砷工业废水的泄漏入渗是佛山市南部顺德区地下水中砷的另一重要来源。受原生沉积环境和人为输入双重作用,三角洲平原区所形成的中性至弱碱性还原环境是高砷地下水赋存的主要成因。A high level of arsenic(As)in groundwater(ρ(As)>10μg/L)is a potential threat to safe drinking water and the ecological environment.The sources of As in groundwater derived from coastal urbanized areas are complex,which mainly include various anthropogenic and geogenic sources.The rapidly urbanized Pearl River Delta was selected as the study area.The occurrence of and key driving factors for As enrichment in the shallow aquifers in areas with different urbanization levels in the Pearl River Delta were evaluated via mathematical statistics and principal component analysis.According to the results,the total dissolved As concentration in shallow groundwater ranged from below the detection limit to 420μg·L^(-1) in the study area,with As(Ⅲ)as the main form.ρ(As)was found to be generally higher in porous aquifers than in fractured or karst aquifers.The proportion of As in the groundwater of urbanized areas was more than five times that of non-urbanized areas.Among the 1567 groups of groundwater samples collected from the study area,89 high As groups,or 5.7%of total,had high level of As(ρ(As)>10μg·L^(-1)).Among them,82 groups were from shallow porous aquifers,4 groups from fissure aquifers,and 3 groups from karst aquifers,accounting for 7.8%,0.8%,and 9.7%of total,respectively.Compared with historical hydrochemical data collected from 2005 to 2008,the averageρ(As)in shallow high As groundwater of newly added construction areas increased by 30%in 10 years.The chemical type of high As groundwater mainly included HCO_(3)-Ca and Cl-Na types,characterized by high pH,low redox potential(Eh),low NO_(3)- concentration,and positive correlation betweenρ(As)and concentrations of NH_(4)^(+),Fe,and Mn or oxygen consumption.Under microbial degradation and mineralization of organic matter,reductive dissolution of As-bearing iron(oxygen)hydroxide in the Quaternary basement muddy sedimentary strata in the Delta plain was identified as the cause of As mobilization.The leaking and infiltration of As-containing industrial wastewa

关 键 词：城镇化扩张 地下水中砷 分布特征 驱动因素 离子比 珠江三角洲 

分 类 号：X523[环境科学与工程—环境工程]