Modeling PCE degradation and associated stable carbon isotope effects

A one-dimensional analytical unsteady transport model calculating the concentrations and isotopic signatures of tetrachloroethylene (PCE) and its daughter products was created. In order to estimate the degradation rates and enrichment factors, the model was inverted using a Genetic Algorithm (GA) combined with a Least Squares Method. This hybrid method divided the computational requirements by at least a factor 2 over the data sets tested. The code was successfully applied to computer-generated data. The isotopic signature profiles were observed to be more sensitive than the concentration ones to both the degradation rate and enrichment factor estimates.; While applying the model to laboratory data, the tetrachloroethylene and trichloroethylene degradation rates were observed to decrease with time and increase with the presence of ethanol. The cis-dichloroethylene and vinyl-chloride degradation rates estimated from the laboratory measurements were not reliable. The enrichment factors did not significantly change either with time, or with ethanol addition.