HR: 09:15h
AN: H21H-06    [Abstracts]
TI: Effects of Source Zone Architecture on Nonaqueous Phase Liquid Dissolution: a Magnetic Resonance Imaging Study
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
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
AB: Magnetic Resonance Imaging (MRI) was used to determine the influence of source zone architecture on nonaqueous phase liquid (NAPL) dissolution in three-dimensional correlated heterogeneous experimental aquifers with two different correlation lengths. Initial spill volumes were varied in each of the two heterogeneous aquifers to achieve different NAPL source zone architectures. Water was purged through the aquifers at a constant Darcy velocity of 1m/day. Three-dimensional images of NAPL were acquired every 10~20 pore volumes (PV) of water flushed, and effluents samples were collected every 5 PV and analyzed with gas chromatography. Results show that effluent concentrations initially increase in the cases of high initial NAPL saturation, and the extent of increase is related to the correlation lengths of the heterogeneous aquifers. In the cases of low initial NAPL saturation, effluent concentrations were found to decrease. Analysis of NAPL images indicates that in cases of high initial NAPL saturation, new flow paths were created as the total surface areas of NAPLs increase initially, and then decrease during dissolution. While in the cases of low initial saturation, total surface areas decrease from the beginning of dissolution. Mass transfer coefficients were determined by assuming one-dimensional flow, and that NAPL above 20% saturation could be treated as pools for the purposes of surface area calculations; mass transfer coefficients stay nearly constant over the courses of dissolution.
DE: 1831 Groundwater quality
SC: Hydrology [H]
MN: Fall Meeting 2005