高砷地下水中氮循环对砷释放过程的影响
Effect of Nitrogen Cycling on Arsenic Release in Groundwater with High Arsenic Content
张振超 1梁莹 1许洁 1姜雪 1马瑞1
作者信息
- 1. 中国地质大学环境学院,长江流域环境水科学湖北省重点实验室,湖北武汉 430078
- 折叠
摘要
高As地下水中往往伴随着高NH4+组分的分布,但是有关氮循环如何影响As迁移释放的研究还较少.江汉平原为高砷地下水分布区,同时地下水中NH4+浓度也普遍较高,本研究旨在探讨江汉平原地下水系统中氮迁移转化对砷组分时空分布的控制过程.对江汉平原不同水体的水化学和同位素指标进行测试,利用氮和砷相关物理化学指标对采样点进行层次聚类分析.结果表明,沿着地下水流方向,由于地下水氧化还原环境等因素的改变,氮反应迁移过程对As释放过程的影响机制也不相同.在补给区附近,地下水处于偏氧化环境,NO3-的富集会抑制铁氧化物溶解过程;沿地下水径流方向,地下水环境向还原条件转化,反硝化作用加强,促进了铁氧化物的溶解并导致As释放到地下水中;在地下水排泄区,地下水环境处于还原状态,反硝化反应进一步增强,可能发生利用Fe2+作为电子供体进行的反硝化反应和DNRA过程,进而通过氧化还原反应影响As释放.
Abstract
Groundwater with high As concentration often contains high NH4+components,but few studies have been conducted to investigate the effect of nitrogen cycling on the migration and release of As. The aquifer system in Jianghan Plain contains high arsenic as well as high content of ammonium in groundwater. The purpose of this study is to explore the effect of nitrogen reactive transport on the As release. In this study,the different water bodies in Jianghan Plain were sampled and their hydrochemical and isotopic indexes were tested,and hierarchical cluster analysis was performed on the sampling sites using the physicochemical indexes related to nitrogen and arsenic. The results show that along the direction of groundwater flow,due to the changes of groundwater redox conditions,the effect of nitrogen redox process on arsenic release process is different. Near the groundwater recharge area,the enrichment of NO3-in the relatively oxidized zone inhibits the dissolution of iron oxide. Along the groundwater flow path,the redox environment of aquifer system changes from oxidized to reduced condition. The enhanced denitrification occurring in the reduced environment could promote the dissolution of iron oxide,resulting in the release of As into groundwater. The denitrification is further enhanced in the groundwater discharge zone,and denitrification and DNRA using Fe2+as electron donor may influence arsenic release.
关键词
高砷地下水/氮素/聚类分析/江汉平原/环境地质/水文地质Key words
high arsenic groundwater/nitrogen/cluster analysis/Jianghan Plain/environmental geology/hydrogeology引用本文复制引用
基金项目
湖北省科技创新群体项目(2019CFA013)
国家自然科学基金项目(41722208)
出版年
2024
NETL
NSTL
万方数据