Effect of Porous Media and Fluid Properties on Dense Non-Aqueous Phase Liquid Migration and Dilution Mass Flux

摘要

The influence of porous media and fluid properties on Non Aqueous Phase Liquid (NAPL) residual geometry and associated contaminant mass flux characteristics was investigated. Contaminant mass flux is a function of the source zone cross sectional area exposed to groundwater flow. Porous media and fluid properties affect source zone morphology leading to cross sectional area development. Media grain size and NAPL wettability were varied for relative comparisons. Fluid properties including density differential and interfacial tension between NAPL and water were varied for relative comparisons. The percent mass flux of perchloroethylene was measured and the relationship between mass flux and mass loading was developed for different systems. Results indicated wettability conditions of the media as well as density differential between fluids had the greatest influence on contaminant flux values from the NAPL source zone. The results showed that as density differential decreased and the media became more hydrophobic, the relationship between relative mass flux and percent mass value changed from a non-linear to a linear relationship. Varying grain size had little effect on the magnitude of mass flux values but showed correlation with the mass flux and mass load relationship. The results indicated that interfacial tension between fluids had minimal effect on mass flux values and a consistent logarithmic relationship between mass flux and mass load was observed. Dissolution experiments using trichloroethylene were completed to determine the relationship between flux values produced during mass loading and flux values produced during mass reduction. The flux development during loading appears to be hysteretic with flux development during mass reduction of dissolution.