Redox Properties and Reactivity of Sorbed Natural Organic Matter

吸附的天然有机物的氧化还原性质和反应性

• 批准号: 338519729
• 负责人: Professor Dr. Stefan Haderlein, since 6/2018
• 金额: --
• 依托单位: Arbeitsgruppe Hydrogeochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/338519729?language=en
• 关键词: Redox; Properties; Reactivity; Sorbed; Natural

Natural organic matter (NOM) is a major diver of biogeochemical redox processes in soils aquifers. The prominent role of NOM in electron transfer reactions arises from is its ability to act as redox buffer as well as an electron shuttle, enhancing reactions between bulk electron donors and acceptors. Although in natural porous media a major fraction of NOM is present in sorbed state, the effect of redox properties (i.e., the electron exchange capacities and the redox state) on NOM sorption to minerals has not been addressed nor the effect of sorption on the redox properties of sorbed NOM. We hypothesize that the redox properties of adsorbed NOM will differ from those of the same type of NOM in the absence of sorbing surfaces. The research proposed here aims at quantifying these changes to provide the basis for a mechanistic understanding of how sorption processes control redox properties and biogeochemical functions of NOM in aqueous systems. Since sorption of NOM also determines the fraction of mobile and immobilized NOM and their respective redox properties, a detailed insight is needed in order to assess which part of NOM will be available and active for processes such as pollutant transformation, microbial respiration or electron shuttling. We suggest to study experimentally the mechanisms in detail that determine the redox properties and redox state of sorbed NOM. Thus, we propose to address the following major research questions in this proposal: - How does sorption of NOM to solid surfaces per se (i.e., in the absence of electron transfer) change its redox properties (electron accepting/donating capacity, redox state, EH distribution, redox mediation capacity)? - How does the redox state of NOM influence its sorption behavior? - How does electron transfer between the sorbent and NOM change the redox properties of sorbed NOM? - How do bulk properties and pretreatment of NOM (origin, aromaticity, acid/base chemistry) affect sorption and electron transfer processes altogether? To this end, we will study experimentally and systematically the mechanisms that determine the redox properties and redox state of sorbed NOM in laboratory batch experiments at environmentally relevant conditions using novel electrochemical techniques and a range of NOM samples and minerals. As NOM coatings are ubiquitous in aquatic systems answers to these questions will allow us to develop a much deeper understanding of heterogeneous redox processes in the subsurface and are a prerequisite for development of quantitative models for predicting biogeochemical processes at the mineral-water interface.

天然有机物（NOM）是土壤含水层中生物地球化学氧化还原过程的主要潜水员。 NOM在电子转移反应中的重要作用来自其充当氧化还原缓冲液以及电子班车的能力，增强了散装电子供体和受体之间的反应。尽管在天然多孔培养基中，NOM的主要部分存在于吸附状态，但尚未解决氧化还原性能（即电子交换能力和氧化还原状态）对矿物质的NOM吸附的影响，也没有解决吸附对吸附NOM的氧化还原特性的影响。我们假设在没有吸附表面的情况下，吸附的NOM的氧化还原特性将与相同类型的NOM类型的氧化还原。这里提出的研究旨在量化这些变化，以提供对吸附过程如何控制氧化还原性能和NOM在水性系统中的生物地球化学功能的基础。由于NOM的吸附还确定了移动和固定的NOM及其各自的氧化还原特性的比例，因此需要详细的见解，以评估NOM的哪些部分将可用，并在诸如污染物转化，微生物呼吸或电子穿梭等过程中有效。我们建议通过实验研究确定氧化还原特性和吸附NOM的氧化还原状态的机制。因此，我们建议在此提案中解决以下主要研究问题： - NOM本身对固体表面的吸附（即在没有电子传输的情况下）如何改变其氧化还原性能（电子接受/捐赠能力，氧化还原状态，EH分布，氧化还原介导能力）？ - 氧化还原状态如何影响其吸附行为？ - 吸附剂和NOM之间的电子转移如何改变吸附NOM的氧化还原性能？ - NOM（原点，芳香性，酸/碱化学）的批量特性和预处理如何影响吸附和电子转移过程？为此，我们将使用新型的电化学技术以及一系列的NOM样品和矿物质在实验室批处理实验中在实验室批处理实验中确定氧化还原特性和吸附NOM的氧化还原状态的机制。 由于在水生系统中无处不在的涂料对这些问题的答案将使我们能够对地下中异质的氧化还原过程有更深入的了解，并且是开发定量模型的先决条件，以预测矿物质 - 水界面的生物地球化学过程。