HR: 0800h
AN: H31A-0363    [Abstracts]
TI: Complete Dissolution of Chlorinated-Solvent Immiscible Liquid in Saturated Sandy Media
AU: * Mahal, M K
EM: mmahal@email.arizona.edu
AF: Department of Soil, Water and Environmental Science, University of Arizona 429 Shantz Bldg, Tucson, AZ 85721 United States
AU: Murao, A
EM: amurao@email.arizona.edu
AF: Department of Soil, Water and Environmental Science, University of Arizona 429 Shantz Bldg, Tucson, AZ 85721 United States
AU: Brusseau, M L
EM: brusseau@ag.arizona.edu
AF: Department of Soil, Water and Environmental Science, University of Arizona 429 Shantz Bldg, Tucson, AZ 85721 United States
AU: Brusseau, M L
EM: brusseau@ag.arizona.edu
AF: Department of Hydrology and Water Resources, University of Arizona 429 Shantz Bldg, Tucson, AZ 85721 United States
AB: Dense immiscible liquids are commonly found in the subsurface beneath hazardous waste sites and can serve as a long-term source of contamination. Complete removal of the immiscible liquid is dependent on dissolution processes. A series of column experiments was conducted to examine the influence of porous-media texture and residual saturation on complete dissolution. Trichloroethene (TCE), a chlorinated solvent, was used as a representative dense immiscible liquid in these experiments. A residual TCE saturation was created by imbibing TCE into the column and then flushing with a saturated aqueous TCE solution to remove the mobile phase. Once a residual saturation was established, the dissolution process was started by flushing the column with an artificial groundwater solution (0.005M CaCl2). The effluent was monitored until the concentration reached 0.1 mg/L. The elution waves exhibited three distinct regions of behavior with respect to the rate of change of concentration. An initial steady-state stage was followed by a transient stage characterized by an exponential decrease in concentration. This was followed by an extensive low-concentration (0.4 to 0.1 ug/L) tail. The former two stages are associated with immiscible-liquid dissolution, whereas the latter is associated with rate-limited sorption/desorption. The results indicate that the elution waves exhibit an asymptotic profile for a portion of the transient stage. The extent of the asymptotic behavior appears to be a function of the uniformity coefficient (Uc), with the greatest extent for the most poorly sorted medium. The asymptotic transient-stage elution effect observed in these experiments can increase the amount of time required to reach concentrations below the maximum contaminant level (MCL).
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting