Quantifying Chloroethene Degradation via Reactive Transport Modeling Incorporating Isotope Fractionation

摘要

The often occurring incomplete natural reductive dechlorination of chloroethenes forms a serious problem for the application of Monitored Natural Attenuation, From laboratory studies, alternative degradation pathways for lower chlorinated compounds such as cw-l,2-dichloroethene (cDCE) and vinyl chloride (VC) are known, but obtaining evidence in the field is difficult. Compound-specific stable isotope analysis (CSIA) is probably the only practically applicable method for studying this, but the interpretation of the isotope data can be very complex. To overcome this problem, a reactive transport model including isotope fractionation has been developed. Here, two cases with chloroethene contaminations are presented in which CSIA has been applied to investigate the occurrence of destructive natural attenuation processes other than reductive dechlorination. In both cases, the isotope data indicate no significant contribution of these processes to the natural attenuation of cDCE and VC.