Fe(II)-Fe(III) Electron Transfer at Fe-containing Clay Minerals and its Effect on Hg(II) and Cr(VI) Transformation

含铁粘土矿物中 Fe(II)-Fe(III) 电子转移及其对 Hg(II) 和 Cr(VI) 转化的影响

• 批准号: 202271526
• 负责人: Dr. Anke Neumann
• 金额: --
• 依托单位: Department of Civil and Environmental Engineering
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/202271526?language=en
• 关键词: Fe; II; III; Electron; Transfer

The Fe(II)/Fe(III) redox couple plays an important role in biogeochemical cycles and for the dynamics of contaminant transformation in soils and aquifers. Despite the abundance of clay minerals in subsurface environments, redox processes of structural Fe in clay minerals as well as their impact on the mobility and toxicity of inorganic contaminants are not well understood. To address this knowledge gap, the proposed research aims to determine whether electron transfer between aqueous Fe(II), a reductant abundant in natural anaerobic environments, and structural Fe(III) in clay minerals occurs and how this reaction influences the transformation of the inorganic contaminants Hg(II) and Cr(VI). Isotope selective 57Fe-Mössbauer spectroscopy and infrared spectroscopy will be used to monitor the oxidation state and the structural environment of Fe in clay minerals and the Fe(III) product will be characterized with microscopic and spectroscopic methods. To gain a better understanding of inorganic contaminant reduction by clay mineral bound Fe(II), Hg(II) and Cr(VI) were chosen as exemplary contaminants, exhibiting complementary properties with regard to accessing the different surfaces of clay minerals. The application of stable isotope fractionation measurement to the non-traditional elements Hg and Cr will generate new insights into processes at the clay mineral-contaminant interface and will add to the further development of these novel isotope systems as source and process tracer. The findings will add to understanding the role of clay mineral bound Fe as a renewable source of redox equivalents in the environment and will improve the ability to assess the fate of contaminants, both inorganic and organic.

Fe(II)/Fe(III)氧化还原对在土壤和含水层中的生物地球化学循环和污染物转化动力学中起着重要的作用。尽管粘土矿物在地下环境中含量丰富，但粘土矿物中结构铁的氧化还原过程及其对无机污染物的迁移性和毒性的影响尚不清楚。为了解决这一认识差距，拟议的研究旨在确定在天然厌氧环境中丰富的还原剂Fe(II)水溶液与粘土矿物中的结构Fe(III)之间是否发生电子转移，以及该反应如何影响无机污染物Hg(II)和Cr(VI)的转化。用同位素选择性~(57)Fe-Mössbauer谱和红外光谱监测粘土矿物中铁的氧化状态和结构环境，并用显微镜和光谱方法对Fe(III)产物进行表征。为了更好地了解粘土矿物结合的Fe(II)、Hg(II)和Cr(VI)对无机污染物的还原作用，我们选择了汞(II)和铬(VI)作为典型污染物，它们在进入粘土矿物不同表面方面表现出互补的性质。将稳定同位素分馏测量应用于非传统元素汞和铬，将对粘土矿物-污染物界面的过程有新的认识，并将促进这些新的同位素系统作为源和过程示踪剂的进一步发展。这些发现将有助于理解粘土矿物结合铁作为环境中氧化还原当量的可再生来源的作用，并将提高评估污染物(包括无机和有机污染物)命运的能力。