« Previous AbstractChemical defense of brood by a social wasp    Next AbstractCan soil gas VOCs be related to groundwater plumes based on their isotope signature? »

Environ Sci Technol

Title:		Chlorine and carbon isotopes fractionation during volatilization and diffusive transport of trichloroethene in the unsaturated zone
Author(s):		Jeannottat S; Hunkeler D;
Address:		"University of Neuchatel, Centre for Hydrogeology & Geothermics, CHYN, Rue Emile Argand 11, CH-2000 Neuchatel, Switzerland"
Journal Title:		Environ Sci Technol
Year:		2012
Volume:		20120307
Issue:		6
Page Number:		3169 - 3176
DOI:		10.1021/es203547p
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"To apply compound-specific isotope methods to the evaluation of the origin and fate of organic contaminants in the unsaturated subsurface, the effect of physicochemical processes on isotope ratios needs to be known. The main objective of this study is to quantify chlorine and carbon isotope fractionation during NAPL-vapor equilibration, air-water partitioning, and diffusion of trichloroethene (TCE) and combinations of these effects during vaporization in porous media. Isotope fractionation is larger during NAPL-vapor equilibration than air-water partitioning. During NAPL-vapor equilibration, carbon, and chlorine isotope ratios evolve in opposite directions although both elements are present in the same bond, with a normal isotope effect for chlorine (epsilon(Cl) = -0.39 +/- 0.03 per thousand) and an inverse effect for carbon (epsilon(C) = +0.75 +/- 0.04 per thousand). During diffusion-controlled vaporization in a sand column, no significant carbon isotope fractionation is observed (epsilon(C) = +0.10 +/- 0.05 per thousand), whereas fairly strong chlorine isotope fractionation occurs (epsilon(Cl) = -1.39 +/- 0.06 per thousand) considering the molecular weight of TCE. In case of carbon, the inverse isotope fractionation associated with NAPL-vapor equilibration and normal diffusion isotope fractionation cancel, whereas for chlorine both processes are accompanied by normal isotope fractionation and hence they cumulate. A source of contamination that aged might thus show a shift toward heavier chlorine isotope ratios"
Keywords:		"Carbon Isotopes/*chemistry Chlorine/*chemistry Groundwater/chemistry Isotopes/chemistry Trichloroethylene/*chemistry Volatilization Water Pollutants, Chemical/*chemistry;"
Notes:		"MedlineJeannottat, Simon Hunkeler, Daniel eng Research Support, Non-U.S. Gov't 2012/02/09 Environ Sci Technol. 2012 Mar 20; 46(6):3169-76. doi: 10.1021/es203547p. Epub 2012 Mar 7"