Naturally produced volatile and polar organohalogens in soils

目前关于土壤中卤代有机化合物的自然(生物和非生物)形成和降解的知识非常有限。目前还不清楚土壤是否以及在什么环境条件下可以充当这些化合物的汇或源。就大气丰度和环境意义而言，自然界中形成的最重要的卤化物无疑是气态卤代甲烷。最近，越来越明显的是，大多数大气中的CH3Cl和CH3Br都来自陆地，而不是海洋。除了一卤化有机卤素外，陆地环境中还会产生多卤化化合物，如挥发性化合物(如CH2Cl2、CHCl3)和极性化合物(如卤代酚、卤代苯甲醇、卤代乙酸、卤苯甲酸、卤苯基乙酸)。研究单位NAFOSA项目的中心假设是，大多数已知的陆地环境中非生物卤化反应方案与自由基化学有关，这些反应是通过三种基本的氧化还原敏感土壤成分--有机物、铁和氧--联系在一起的。卤化物似乎偶然地参与了这些土壤反应。为了解决卤化过程的热点，有必要量化生物过程中还原的有机物与次生氧化物矿物(Fe，Mn)的反应表面接触时的反应周转数。虽然NAFOSA主要研究挥发性化合物，但NAVOPOS项目还打算揭开硬币的另一面：识别和定量分析非生物降解过程中的极性卤化物。

The present knowledge of the natural (biotic and abiotic) formation and degradation of halogenated organic compounds in soils is very limited. It is not clear whether, and under which environmental conditions soils can act as a sink or source of these compounds. In terms of atmospheric abundance and environmental significance the most important halogenated compounds formed in nature are undoubtedly the gaseous halomethanes. Recently it has become apparent that most atmospheric CH3Cl and CH3Br have a terrestrial rather than a marine origin. Besides monohalogenated organohalogens, polyhalogenated compounds such as volatile (e.g. CH2Cl2, CHCl3) and polar (e.g. halophenols, haloanisols, haloacetic acids, halobenzoic acids, halophenylacetic acids) compounds are produced in the terrestrial environment. The central hypothesis of the Research Unit project NAFOSA is that most of the known reaction schemes for the abiotic halogenation in the terrestrial environment are linked to radical chemistry by three essential redox-sensitive soil constituents - organic matter, iron, and oxygen. It seems to be by chance that halides are involved in these soil reactions. To address the hot spots of halogenation processes it is necessary to quantify the reaction turnover numbers of reduced organic material delivered by biotic processes in contact with reactive surfaces of secondary oxidic minerals (Fe, Mn). While NAFOSA is heading mainly for volatile compounds, the project NAVOPOS is additionally intending to unravel the flip side of the coin: Identification and quantitation analysis of polar halogenated compounds from abiotic degradation processes.