内蒙古哈素海区域高砷地下水化学特征及其成因  

Hydrogeochemical Characteristics and Genesis of High-arsenic Groundwater in Hasuhai Area,Inner Mongolia

作　　者：冯彦博 董少刚 雷君豪 张敏 王锟 FENG Yan-bo;DONG Shao-gang;LEI Jun-hao;ZHANG Min;WANG Kun(School of Ecology and Environment,Inner Mongolia University,Hohhot,Inner Mongolia 010021;Inner Mongolia Key Laboratory of River and Lake Ecology,Hohhot,Inner Mongolia 010021)

机构地区：[1]内蒙古大学生态与环境学院,内蒙古呼和浩特010021 [2]内蒙古自治区河流与湖泊生态重点实验室,内蒙古呼和浩特010021

出　　处：《地球学报》2023年第3期522-530,共9页Acta Geoscientica Sinica

基　　金：内蒙古“一湖两海”科技重大专项项目(编号:ZDZX2018054);内蒙古自治区自然科学基金项目(编号:2018MS04004);国家自然科学基金项目(编号:41562020)联合资助。

摘　　要：哈素海区域高砷地下水对当地居民饮用水安全造成严重威胁,揭示其形成演化机制对科学合理的开发利用水资源、保障居民身体健康具有重要意义。本文在水文地质调查的基础上,应用Piper三线图、PHREEQC的砷形态计算及相关性分析等方法,研究高砷地下水化学特征、构建砷形态模型(SM)和砷吸附模型(HSM),以揭示高砷地下水的成因机制。结果表明,研究区砷浓度为0.2~231.5μg/L,高砷区主要分布在大青山以南的冲湖积平原区;地下水砷的类型以As(Ⅲ)为主,SM分析显示优势形态为H_(3)AsO_(3),HSM分析显示存在Hfo_wH_(2)AsO_(3)和H_(3)AsO_(3)两种主要形态。地下水中的砷化物可能来源于山区富砷岩石的风化溶解以及第四系富砷河湖相沉积物;研究区河湖相沉积环境是高砷水形成的前提,有机质分解主导的还原环境是导致砷从含水介质释放到地下水中的主要因素,弱碱性环境和HCO-3的竞争吸附也会引起砷的释放。High-arsenic groundwater in Hasuhai area poses a serious threat to the safety of drinking water for local residents.Elucidating its formation and evolution mechanism is of great significance to the scientific and sustainable development and utilization of water resources and the protection of the health of local residents.Based on hydrogeological investigations,we herein employed Piper diagrams,arsenic speciation calculations using PHREEQC,and correlation analysis to investigate high-arsenic groundwater.We studied the hydrogeochemical characteristics and constructed an arsenic speciation model(SM)and arsenic sorption model(HSM)to reveal the genetic mechanism of high-arsenic groundwater in the study area.Arsenic concentrations were found to vary between 0.2 and 231.5µg/L,and high arsenic groundwater was mainly distributed in the alluvial plain south of Daqingshan Mountain.As(Ⅲ)was the main type of arsenic in shallow groundwater in the study area.SM showed that H_(3)AsO_(3) was the dominant form of arsenic in the study area,whereas HSM showed that there were two main forms of arsenic,H_(3)AsO_(3) and Hfo_wH_(2)AsO_(3).Arsenic in groundwater may originate from the dissolution and weathering of the surrounding arsenic-rich rocks and Quaternary arsenic-rich fluvial and lacustrine sediments.The fluvial and lacustrine sedimentary environment in the study area is conducive to the formation of high-arsenic water,and the weakly alkaline reducing environment dominated by the decomposition of organic matter is the main driver of the transfer of arsenic from aquifers to groundwater.Additionally,the competitive adsorption of HCO-3 promotes the release of arsenic.

关 键 词：高砷水 砷形态 还原环境 PHREEQC 竞争吸附 

分 类 号：X523[环境科学与工程—环境工程] P641.69[天文地球—地质矿产勘探]