厌氧环境中DOM对汞络合与还原/氧化的耦联作用机制

项目名称： 厌氧环境中DOM对汞络合与还原/氧化的耦联作用机制

项目编号： No.41271464

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 天文学、地球科学

项目作者： 卞永荣

作者单位： 中国科学院南京土壤研究所

项目金额： 75万元

中文摘要： 可溶性有机质（DOM）影响汞的形态分布、迁移转化及生物可利用性。以往研究主要在有氧条件下进行，而厌氧条件下DOM与汞的氧化还原和络合反应之间的耦联机制仍不清楚，需要进一步研究。前期初步研究发现还原态DOM不仅对Hg(Ⅱ)有还原与络合双重作用，而且当还原态DOM与Hg(0)共存时，DOM与元素汞也能迅速发生反应，然而其作用机制还不清楚。本项目分别用微生物法和化学法制备还原态DOM，在厌氧条件下进一步研究DOM与Hg(Ⅱ)的还原和络合的耦合关系及DOM与Hg(0)可能存在配位诱导性氧化络合机制。以含有不同氧化还原活性和络合能力的功能团的有机物质作为模型化合物，利用红外光谱和EXAFS/XANES等技术表征手段，研究汞与DOM的相互作用，阐明DOM与Hg(II)/Hg(0)的络合、氧化和还原耦联作用机制。该研究可为认识汞的形态分布和转换、生物地球化学循环提供科学依据。

中文关键词： 汞；可溶性有机质；重金属；生物质炭；络合作用

英文摘要： Mercury is affected by Dissolved Oganic Matter(DOM) in speciation transformations, global transportation and bioavailability, and yet mechanics of transformations of Hg is knowledge gap in the anoxic environments, specially the couples of redox and complexation between DOM and Hg.Preliminary investigation, We found the dual role played by DOM in the reduction and complexation of mercury is likely widespread in anoxic sediments and water, and the reaction between reduced DOM and Hg(0) need to improve these mechanisms. This proposal intends to study the mechanism of Hg(II) reduction and complexation by reduced DOM in anoxic environments, and interactions between reduced DOM and Hg(0) under anoxic dark conditions. The reduced DOM will be prepared by microbiological and chemical methods, respectively. In order to elucidate the role of functional groups in interactions between mercury and reduced DOM, organic compounds containing groups (such as low-molecular-weight thiols) with different redox and complexing activities will be used as dissolved organic substances. Additionally, Infrared spectra and extended X-ray fine-structure absorption spectroscopy (EXAFS and XANES) will be used to elucidate the chemical bonding and mechanisms of the reactions. Reveal the dual character of the DOM in the redox reaction and compl

英文关键词： mercury；dissolved organic matter；heavy metal；biochar；complexation