HR: 10:20h
AN: H42A-01    [Abstracts]
TI: The Impact of Non-Ideal Sorption on Low-Concentration Tailing Behavior for Chlorinated Solvents in Aquifer Material
AU: * Schnaar, G
EM: gschnaar@email.arizona.edu
AF: Department of Soil, Water and Environmental Science, 429 Shantz Building, Tucson, AZ 85721 United States
AU: Brusseau, M L
EM: brusseau@ag.arizona.edu
AF: Department of Soil, Water and Environmental Science, 429 Shantz Building, Tucson, AZ 85721 United States
AU: Brusseau, M L
EM: brusseau@ag.arizona.edu
AF: Department of Hydrology, Harshbarger Building, Tucson, AZ 85721 United States
AB: Laboratory experiments were conducted to investigate long-term elution behavior of trichloroethene and tetrachloroethene for two aquifer sands. Specifically, we examined the relative impact of rate-limited sorption, non-linear sorption, and competitive sorption on long-term, low concentration elution tailing that is associated with water flushing of contaminated aquifer material. Additionally, we investigated the existence and potential impacts of hysteresis of sorption/desorption. Rate-limited sorption effects were examined using miscible-displacement experiments and batch rate studies. In addition, both batch and column experiments were conducted using several initial aqueous concentrations spanning a wide range to evaluate the impact of non-linear sorption. The effect of organic co-solutes on sorption processes was assessed by varying co-solute concentrations in both batch-isotherm and miscible-displacement experiments. Rate parameters were obtained by calibration of measured data using a form of the advection-dispersion equation which describes sorption as a microscopically heterogeneous process with a continuous distribution of domains. The effect of column residence time and input mass on tailing and associated rate parameters was examined. Concentrations as low as eight orders of magnitude below the initial concentrations were observed in water-saturated miscible-displacement experiments. Truncation of column breakthrough curves was found to have a strong influence on both independently determined and calibrated sorption parameters. Furthermore, experimental conditions, such as input mass, were found to have an impact on calculated sorption parameters. Based on our results, the relative contributions of rate-limited, non-linear, and competitive sorption on long-term elution tailing will be discussed.
DE: 1803 Anthropogenic effects
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting