Carbon isotope fractionation during abiotic reductive dehalogenation of trichloroethene (TCE)

Dehalogenation of trichloroethene (TCE) in the aqueous phase, either on pal ladium catalysts with hydrogen as the reductant or on metallic iron, was as sociated with strong changes in delta C-13. In general, the delta C-13 of p roduct phases were more negative than those of the parent compound and were enriched with time and fraction of TCE remaining. For dehalogenation with iron, the delta (13) C of TCE and products varied from -42 parts per thousa nd. to + 5 parts per thousand. For the palladium experiments, the final pro duct, ethane, reached the initial delta C-13 of TCE at completion of the de halogenation reaction. During dehalogenation, the carbon isotope fractionat ion between TCE and product phases was not constant. The variation in delta C-13 of TCE and products offers a new monitoring tool that operates indepe ndently of the initial concentration of pollutants for abiotic degradation processes of TCE in the subsurface, and may be useful for evaluation of rem ediation efficiency. (C) 2001 Elsevier Science Ltd. All rights reserved.