ASSESSMENT OF THE POTENTIAL FOR THE BACTERIAL DEGRADATION OF TETRACHLOROETHENE AND TRICHLOROETHENE IN THE VADOSE ZONE OF TWO VEGETATED SLIMES DAMS

ii The aim of this project is to assess the potential for the bacterial degradation of tetrachloroethene (PCE) and trichloroethene (TCE) in the vadose zone of two vegetated slimes dams, Dam 2 and Dam 3/4. The focus is on the reductive dechlorination of PCE and TCE; however, the degradation of dichloroethene (DCE) and vinyl chloride (VC), which are the carcinogenic daughter products of reductive dechlorination, via oxidation, is also investigated. The spatial and temporal variability of the reductive dechlorination and oxidation potentials within the dams are measured, and the influence of the vegetation on this degradation is determined. The spatial variation in the reductive dechlorination potential in the vadose zone is ascertained by modifying a points system originally devised for the groundwater. The resultant points system includes the water content, redox potential, pH, temperature, the carbon source (including the measurement of soil organic matter and BTEX compounds) and the pollutants and daughter products, all of which are measured at various sites and depths o