Natural Formation of Vinyl Chloride in the Terrestrial Environment

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• 作者：Frank Keppler ; Reinhard Borchers ; Jens Pracht ; Stefan Rheinberger ; and Heinz F. Schö ; ler
• 刊名：Environmental Science & Technology
• 出版年：2002
• 出版时间：June 1, 2002
• 年：2002
• 卷：36
• 期：11
• 页码：2479 - 2483
• 全文大小：102K
• 年卷期：v.36,no.11(June 1, 2002)
• ISSN：1520-5851

文摘

Vinyl chloride is a highly reactive and toxic substancewhich is widely used in industry. It is the parent compoundof poly(vinyl chloride) (PVC), one of the most importantindustrial polymers. Until now, it was thought that vinylchloride found in the environment is exclusively man-madeor results from the degradation of other anthropogenicsubstances, such as trichloroethylene and tetrachloroethylene. Here, we demonstrate that vinyl chloride also hasnatural sources. Soil air and ambient air from a rural areain Northern Germany were investigated for volatilechlorinated halocarbons. The concentrations of vinylchloride in the soil air were significantly enhanced ascompared to ambient air, indicating a natural formation ofthis compound in the soil. A series of laboratory experimentsusing different soils and model compounds was conducted,which clearly proved that vinyl chloride could be producedduring soil processes. We propose that this highlyreactive compound can be formed during the oxidativedegradation of organic matter in soil, for example, in areaction between humic substances, chloride ions and anoxidant (ferric ions or hydroxyl radicals). The redox-sensitive aromatic compounds in soil such as catecholsand o-quinones can be degraded to CO₂, accompanied bythe release of vinyl chloride and other volatile chlorinatedcompounds. This process could have started in theLate Silurian to Early Devonian, 400 million years ago,when the first soils on earth evolved.