ABSTRACT
Natural attenuation of a large trichloroethene (TCE) plume has been evaluated through the analysis of TCE transport relative to two co-contaminants, tetrachloroethene (PCE) and tritium. This approach allowed degradation to be estimated, independent of dispersion and sorption. A TCE degradation half-life in the range of 8 to 17 years was estimated relative to tritium and PCE. The significance of distinguishing dispersion from degradation was shown through both an analytical and a numerical model revealing that the effect of dispersion on attenuation of concentrations in a plume whose source has been removed is not constant with time. Based on laboratory microbiological screening studies and field data, aerobic cometabolism has been identified as a potential mechanism for the observed TCE degradation.
