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J Contam Hydrol

Title:		Design and laboratory testing of a chamber device to measure total flux of volatile organic compounds from the unsaturated zone under natural conditions
Author(s):		Tillman FD; Smith JA;
Address:		"National Research Council, US Environmental Protection Agency, Ecosystems Research Division, 960 College Station Road, Athens, GA 30605, USA. Tillman.Fred@epa.gov "
Journal Title:		J Contam Hydrol
Year:		2004
Volume:		75
Issue:		1-Feb
Page Number:		71 - 90
DOI:		10.1016/j.jconhyd.2004.04.005
ISSN/ISBN:		0169-7722 (Print) 0169-7722 (Linking)
Abstract:		"To determine if an aquifer contaminated with volatile organic compounds (VOCs) has potential for natural remediation, all natural processes affecting the fate and transport of VOCs in the subsurface must be identified and quantified. This research addresses the quantification of air-phase volatile organic compounds (VOCs) leaving the unsaturated zone soil gas and entering the atmosphere-including the additional flux provided by advective soil-gas movement induced by barometric pumping. A simple and easy-to-use device for measuring VOC flux under natural conditions is presented. The vertical flux chamber (VFC) was designed using numerical simulations and evaluated in the laboratory. Mass-balance numerical simulations based on continuously stirred tank reactor equations (CSTR) provided information on flux measurement performance of several sampling configurations with the final chamber configuration measuring greater than 96% of model-simulated fluxes. A laboratory device was constructed to evaluate the flux chamber under both diffusion-only and advection-plus-diffusion transport conditions. The flux chamber measured an average of 82% of 15 diffusion-only fluxes and an average of 95% of 15 additional advection-plus-diffusion flux experiments. The vertical flux chamber has the capability of providing reliable measurement of VOC flux from the unsaturated zone under both diffusion and advection transport conditions"
Keywords:		Air Movements Air Pollutants/*analysis Clinical Laboratory Techniques Diffusion Environmental Monitoring/instrumentation/*methods Gases/*analysis Organic Chemicals/*analysis Soil/*analysis Volatilization;
Notes:		"MedlineTillman, Fred D Jr Smith, James A eng Research Support, U.S. Gov't, Non-P.H.S. Netherlands 2004/09/24 J Contam Hydrol. 2004 Nov; 75(1-2):71-90. doi: 10.1016/j.jconhyd.2004.04.005"