HR: 1340h
AN: H23D-1629    [Abstracts]
TI: Comparison of Models Used to Evaluate Mass Removal and Mass Flux Reduction
AU: * DiFilippo, E L
EM: edifilip@hwr.arizona.edu
AF: Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, United States
AU: Marble, J C
EM: jmarble@hwr.arizona.edu
AF: Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, United States
AU: Marble, J C
EM: jmarble@hwr.arizona.edu
AF: Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721, United States
AU: Tick, G R
EM: gtick@geo.ua.edu
AF: Department of Geological Sciences, University of Alabama, Tuscaloosa, AL 35487, United States
AU: Zhang, Z
EM: henryzzhang@gmail.com
AF: Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721, United States
AU: Brusseau, M L
EM: brusseau@ag.arizona.edu
AF: Department of Hydrology and Water Resources, University of Arizona, 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, Tucson, AZ 85721, United States
AB: The purpose of this study was to investigate the application of models of varying complexity to the dissolution of non-uniformly distributed immiscible liquid in physically heterogeneous systems at both the intermediate and field scale. Flow cell experiments focused specifically on characterizing the relationship between mass flux reduction and mass removal for systems wherein immiscible liquid is poorly accessible to flowing water. Both end-point and time continuous data from several field studies were examined to evaluate observed relationships between mass flux reduction and source-zone mass removal. Methods for estimating mass-flux- reduction/mass-removal behavior, based on the use of simple mass-removal functions and 1-D and 3-D mathematical flow and transport models, were applied to the measured data. The simple mass-removal function generated singular curves that could not reproduce the multi-step behavior exhibited by data from both laboratory and field studies. The permeability field and the distribution of the immiscible-liquid zones were represented explicitly in the 3-D model. In contrast, the system was conceptualized as a pseudo-homogeneous medium, with immiscible liquid uniformly distributed throughout the system for the 1-D modeling. With this approach, all factors that influence immiscible-liquid dissolution are incorporated into the calibrated dissolution rate coefficient, which in such cases serves as a composite or lumped term. The calibrated dissolution rate coefficients obtained for the 1-D modeling were approximately two to three orders of magnitude smaller than the values obtained from column experiments, and which were used for the 3-D modeling. The disparity in magnitudes of the values used for the 1-D and 3-D modeling reflects the difference in implicit versus explicit consideration of the larger-scale factors influencing immiscible-liquid dissolution in the systems. However, the calibrated dissolution rate coefficients were similar for the various flow-cell experiments, which suggest that the model was relatively insensitive to the specific nature of the source-zone configuration.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2007 Fall Meeting