HR: 1340h
AN: H23A-1418    [Abstracts]
TI: Evaluation of Surfactant-Enhanced Nonaqueous Phase Liquid Dissolution in Heterogeneous Permeability Fields Using Magnetic Resonance Imaging
AU: Werth, C J
EM: werth@uiuc.edu
AF: Department of Civil and Environmental Engineering, University of Illinois at Urbana Champaign, 205 N Mathews Ave, Urbana, IL 61801 United States
AU: * Zhang, C
EM: czhang@uiuc.edu
AF: Department of Civil and Environmental Engineering, University of Illinois at Urbana Champaign, 205 N Mathews Ave, Urbana, IL 61801 United States
AB: Porous media heterogeneity has great impact on nonaqueous phase liquid (NAPL) migration, entrapment, dissolution, and cleanup in groundwater. In this study, magnetic resonance imaging (MRI) was used to determine NAPL source zone architectures during surfactant enhanced NAPL dissolution in two experimental aquifers containing three-dimensional correlated heterogeneous permeability fields. Surfactant flow paths were also determined by imaging the breakthrough of a paramagnetic tracer. In both aquifers, preferential flow occurred in high permeability materials with low NAPL saturations. Since the NAPL saturation increased with depth, NAPL was preferentially removed from the upper parts of the aquifers. Effluent measurements indicate that NAPL was removed by enhanced solubilization. However, comparison of three-dimensional NAPL images acquired before and after surfactant flushing indicate that NAPL also migrated downward and created a large pool at the bottom of the aquifer. The downward NAPL migration was more evident in the aquifer with a shorter horizontal correlation length. The enhanced solubilization and redistribution of NAPL in the aquifers after surfactant flushing resulted in a reduction in NAPL mass flux values. This reduction was less for the aquifer with shorter horizontal correlation length, because in this experiment downward NAPL migration created additional NAPL pools in the bottom of the aquifer.
DE: 1831 Groundwater quality
SC: Hydrology [H]
MN: Fall Meeting 2005