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Environ Pollut

Title:		Biodegradation of vapor-phase toluene in unsaturated porous media: Column experiments
Author(s):		Khan AM; Wick LY; Harms H; Thullner M;
Address:		"Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany. Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany. Electronic address: lukas.wick@ufz.de"
Journal Title:		Environ Pollut
Year:		2016
Volume:		20160115
Issue:
Page Number:		325 - 331
DOI:		10.1016/j.envpol.2016.01.013
ISSN/ISBN:		1873-6424 (Electronic) 0269-7491 (Linking)
Abstract:		"Biodegradation of organic chemicals in the vapor phase of soils and vertical flow filters has gained attention as promising approach to clean up volatile organic compounds (VOC). The drivers of VOC biodegradation in unsaturated systems however still remain poorly understood. Here, we analyzed the processes controlling aerobic VOC biodegradation in a laboratory setup mimicking the unsaturated zone above a shallow aquifer. The setup allowed for diffusive vapor-phase transport and biodegradation of three VOC: non-deuterated and deuterated toluene as two compounds of highly differing biodegradability but (nearly) identical physical and chemical properties, and MTBE as (at the applied experimental conditions) non-biodegradable tracer and internal control. Our results showed for toluene an effective microbial degradation within centimeter VOC transport distances despite high gas-phase diffusivity. Degradation rates were controlled by the reactivity of the compounds while oxic conditions were found everywhere in the system. This confirms hypotheses that vadose zone biodegradation rates can be extremely high and are able to prevent the outgassing of VOC to the atmosphere within a centimeter range if compound properties and site conditions allow for sufficiently high degradation rates"
Keywords:		"Biodegradation, Environmental Gases/metabolism Groundwater/chemistry *Models, Chemical Porosity Soil Toluene/analysis/*metabolism Volatile Organic Compounds/metabolism Water Pollutants, Chemical/analysis/*metabolism Biodegradation Gas phase Isotopically l;"
Notes:		"MedlineKhan, Ali M Wick, Lukas Y Harms, Hauke Thullner, Martin eng Research Support, Non-U.S. Gov't England 2016/01/18 Environ Pollut. 2016 Apr; 211:325-31. doi: 10.1016/j.envpol.2016.01.013. Epub 2016 Jan 15"