| 江汉平原高砷地下水中DOM三维荧光特征及其指示意义 |
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| 引用本文： | 鲁宗杰,邓娅敏,杜尧,沈帅,马腾.江汉平原高砷地下水中DOM三维荧光特征及其指示意义[J].地球科学,2017,42(5):771-782. |
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| 作者姓名： | 鲁宗杰 邓娅敏 杜尧 沈帅 马腾 |
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| 作者单位： | 1.中国地质大学地质调查研究院，湖北 武汉 430074 |
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| 基金项目： | 中央高校基本科研业务费专项基金“摇篮计划”CUGL140412国家自然科学基金面上项目41572226中国地质调查局项目12120114069301中国地质调查局项目121201001000150121 |
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| 摘 要： | 水体中溶解性有机质(dissolved organic matter, DOM)是含水层中砷释放的主控因素之一.江汉平原河湖众多、沟渠广布，地表水体与浅层地下水的交互作用使得DOM的组分特征及其强度有显著差异.为查明江汉平原地下水中溶解性有机质在砷迁移转化过程中的作用，对江汉平原地表水和浅层地下水进行三维荧光光谱分析，使用平行因子分析法提取水体中有机质的分子组成、功能特点和荧光特征，并分析各组分相对含量与地下水中砷与铁的关联.江汉平原水体中DOM包括3种主要组分，组分C1、C2为类腐殖质，C2是生物降解过程中产生的小分子，C3为类蛋白物质.地下水DOM以类腐殖质组分C1、C2为主，地表水以类蛋白类物质C3和小分子腐殖质C2为主.高砷地下水中DOM以陆源为主，主要通过两种途径促进As的迁移转化:(1) DOM的腐殖质组分充当微生物群落的电子运输工具，促进微生物作用下的有机质氧化和铁氧化物的还原，并伴随As的释放及大量溶解性有机碳(dissolved organic carbon, DOC)和HCO3-的产生；(2) As以铁等金属阳离子为桥接物与腐殖质结合，通过形成As-Fe-DOM络合物，导致地下水中砷的迁移.
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| 关 键 词： | 江汉平原 砷 溶解性有机质 三维荧光光谱 平行因子分析法 水文地质 |
| 收稿时间： | 2016-11-30 |
EEMs Characteristics of Dissolved Organic Matter and Their Implication in High Arsenic Groundwater of Jianghan Plain |
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| Abstract: | Dissolved organic matter (DOM) is one of the key factors controlling the release of arsenic from sediment to groundwater. There are abundant surface water systems with rivers, lakes, streams and ponds in the Jianghan plain, densely covered by irrigation canals and ditches. The interactions between surface water and shallow groundwater may significantly affect the characteristics and strength of DOM in water. In order to elaborate the roles of DOM on arsenic mobilization in groundwater of Jianghan plain, this study analyzes surface water and groundwater samples using excitation-emission matrix spectroscopy (EEMs) and characterizes the dissolved organic matter of its functional groups, molecular, fluorescence using PARAFAC (parallel factor analysis). It is found that dissolved organic matter in Jianghan plain mainly includes three different components, of which C1 and C2 are humic-like substances and C3 is characterized by protein-like substances. The main components of dissolved organic matter in groundwater are C1 and C2, whilst the dissolved organic matter in surface water is mostly C2 and C3. Dissolved organic matter in groundwater dominated by terrestrial materials, promotes the mobilization of arsenic in two ways. (1) The humic substances act as an electron shuttle for microbial communities, promoting the microbially mediated oxidation of organic matter and reduction of Fe oxides with the release of arsenic and the production of large amounts of DOC (dissolved organic carbon)and HCO3-; (2) Complexation of As with DOM via the bridging of metal cations (such as Fe) enhances the mobility of As in groundwater. |
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