HR: 0801h
AN: NS11B-0497    [Abstracts]
TI: Field and Laboratory Investigations of Enhanced Biological Activity Influencing Groundwater Velocity and Electromagnetic Wave Propagation
AU: * Schillig, P C
EM: schillig@ku.edu
AF: University of Kansas, 1475 Jayhawk Blvd, Lawrence, KS 66045, United States
AU: Devlin, J F
EM: jfdevlin@ku.edu
AF: University of Kansas, 1475 Jayhawk Blvd, Lawrence, KS 66045, United States
AU: Tsoflias, G P
EM: tsoflias@ku.edu
AF: University of Kansas, 1475 Jayhawk Blvd, Lawrence, KS 66045, United States
AU: Patterson, E
EM: elisha04@ku.edu
AF: University of Kansas, 1475 Jayhawk Blvd, Lawrence, KS 66045, United States
AU: Roberts, J A
EM: jaroberts@ku.edu
AF: University of Kansas, 1475 Jayhawk Blvd, Lawrence, KS 66045, United States
AU: McGlashan, M A
EM: michael.a.mcglashan@exxonmobil.com
AB: Field observations of groundwater velocity using point velocity probes (PVPs) and aquifer dielectric properties using ground penetrating radar (GPR) were made in a bioremediating, gasoline contaminated aquifer to which dissolved oxygen was introduced using Oxygen Release Compound (ORCŪ). PVPs are sensitive to changes in groundwater flow; whereas GPR is sensitive to changes in the dielectric and geoelectric properties of the pore- fluid and aquifer material. Therefore, the two methods provided complimentary and independent evidence for pore-scale changes associated with enhanced biological activity. Following the addition of ORC, PVP and GPR measured velocities nearest the ORC wells changed in a consistent manner throughout the experiment. GPR velocities measured further down-gradient, outside the influence of the ORC, did not indicate the same trend. Results from geochemical and flow modeling, combined with gas and biomass measurements, show that PVP and GPR velocity changes were not artifacts of seasonally fluctuating hydraulic gradient or temperature. Rather, the changes appear to be caused by factors related to elevated levels biological activity in the aquifer. Preliminary geophysical laboratory testing in a large sandbox reactor previously identified consistent trends with field GPR data that mirrored the field observations. A new, more detailed, laboratory experiment using GPR and PVPs was initiated to 1) confirm with confidence the phenomena observed in the field and the preliminary lab tank experiment, and 2) to gain additional understanding of the mechanisms responsible for PVP and GPR responses. At the time of writing, the results of the detailed experiment are pending.
DE: 0416 Biogeophysics
DE: 0418 Bioremediation
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
SC: Near-Surface Geophysics [NS]
MN: 2007 Fall Meeting