Formation of volatile organohalogens by microbially catalyzed redox reactions of iron minerals and humic substances

通过微生物催化铁矿物和腐殖质的氧化还原反应形成挥发性有机卤素

• 批准号: 51155766
• 负责人: Professor Dr. Andreas Kappler
• 金额: --
• 依托单位: Arbeitsgruppe Geomikrobiologie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/51155766?language=en
• 关键词: Formation; volatile; organohalogens; microbially; catalyzed

Organohalogens, organic compounds containing halogens such as chlorine, are of environmental concern. In particular because they influence atmospheric chemistry and thus the earth climate, the identification of the sources of organohalogens and an understanding of the mechanisms that lead to formation of organohalogens are necessary. From recent studies it became evident that not only biotic processes but maybe to an even larger extent also abiotic redox reactions involving humic substances and iron minerals can lead to the formation of organohalogens. However, the mechanisms of these reactions and in particular the identity of the reactive organic and iron species leading to the formation of organohalogens are unclear. Whether microbial redox transformation of humic substances and iron minerals can produce such reactive organic and iron species and thereby stimulate the formation of organohalogens is not known at all. The main goal of this research project therefore is to determine whether microbial redox reactions of Fe(ll)- and Fe(lll)-minerals and humic substances can produce reactive iron species and humic compounds that lead to the formation of polar and volatile organohalogens (POX and VOX). For this purpose microcosms will be setup with either pure cultures of ironmetabolizing bacteria or with microbially active soil samples from an organohalogen-releasing field site. These biotic systems will be compared to abiotic ones. One particular goal of this research project is to determine the reactive iron species and to identify the reactive functional groups in the humic substances. Because of the ubiquity of humic substances and Fe(lll)-minerals and the variety of chemical and microbiological processes that are able to reduce and oxidize humic substances and iron minerals, these reactions have the potential to play a key role in the formation of volatile organohalogens and for their release into the atmosphere.

有机卤素，即含有氯等卤素的有机化合物，是环境问题。特别是因为它们影响大气化学，从而影响地球气候，因此有必要确定有机卤素的来源并了解导致有机卤素形成的机制。从最近的研究中可以明显看出，不仅生物过程，甚至在更大程度上，涉及腐殖质和铁矿物的非生物氧化还原反应也可以导致有机卤素的形成。然而，这些反应的机制，特别是导致有机卤素形成的反应性有机和铁物种的身份尚不清楚。腐殖质和铁矿物的微生物氧化还原转化是否能产生这种活性有机和铁物种，从而刺激有机卤素的形成，目前还完全不清楚。因此，本研究项目的主要目标是确定Fe(11)和Fe(11)-矿物和腐殖质的微生物氧化还原反应是否会产生活性铁物种和腐殖质化合物，从而导致极性和挥发性有机卤素(POX和VOX)的形成。为此，将用铁代谢细菌的纯培养物或来自有机卤素释放现场的微生物活跃的土壤样本建立微型宇宙。这些生物系统将被与非生物系统进行比较。本研究项目的一个特殊目标是确定腐殖质中的活性铁物种和确定活性官能团。由于腐殖质和Fe(11)矿物的普遍存在，以及能够还原和氧化腐殖质和铁矿物的各种化学和微生物过程，这些反应有可能在挥发性有机卤素的形成和释放到大气中发挥关键作用。