地下水氮循环与砷迁移转化耦合的研究现状和趋势

Research status and trend of coupling between nitrogen cycle and arsenic migration and transformation in groundwater systems

地下水中铵根、砷、溶解铁的共存是一个普遍现象。它们之间发生强烈的相互作用,并影响地下水系统的氮循环和砷迁移转化。文章在系统总结地下水氮循环过程及影响因素、地下水氮循环功能微生物及特征、地下水砷富集的水文地球化学过程等国内外研究现状的基础上,深入分析了地下水系统中的氮循环过程(硝化、反硝化、铁铵氧化、厌氧铵氧化、硝酸根异化还原产铵等)对地下水砷迁移转化的影响,总结出含水层中铁氧化物和溶解态Fe(Ⅱ)的动态转化是氮循环影响地下水中砷迁移转化的重要桥梁。据此提出不同氧化还原环境的含水层中氮循环过程、地下水氮循环与砷迁移转化耦合机理、Fe(Ⅲ)-Fe(Ⅱ)的循环-地下水氮循环-砷迁移转化之间的相互作用过程、地表水-地下水相互作用带氮-铁-砷的循环过程及其对人类活动的响应等是今后该领域需要关注的重要科学问题和主要发展趋势。这些科学问题的解决不仅有利于识别地下水中氮的来源和迁移转化,而且有利于提高对高砷地下水富集机理的整体认识。

The coexistence of ammonium, arsenic and dissolved iron in groundwater is a common phenomenon in aquifer systems. They have a strong interaction and affect the nitrogen cycling and the migration and transformation of arsenic in groundwater systems. Based on the systematic survey of international and national literature on the process and influencing factors of groundwater nitrogen cycling, the functional microorganisms and their characteristics related to groundwater nitrogen cycling, and the hydrogeochemical process of arsenic enrichment in groundwater, this paper deciphers effects of nitrogen cycling(including nitrification, denitrification,Feammox, Anammox, and dissimilatory nitrate reduction to ammonium) on the migration and transformation of arsenic in groundwater. We proposed that the dynamic transformation of iron oxides and dissolved Fe(Ⅱ) in aquifers is an important bridge for nitrogen cycling and the migration and transformation of arsenic in groundwater. The processes of nitrogen cycling in aquifers with different redox environments, the coupling mechanism between nitrogen cycling and arsenic migration and transformation, the interactions among Fe(Ⅲ)-Fe(Ⅱ) cycling, nitrogen cycling, and arsenic migration and transformation, nitrogen-iron-arsenic cycling in the surface water-groundwater interaction zone and its response to human activities are important scientific issues and research trend that need to be paid attention to in this field in the future. The solution of these scientific problems is not only conducive to identifying the source, migration and transformation of nitrogen in groundwater, but also beneficial to improving the systematical understanding of enrichment mechanism of groundwater arsenic.