HR: 17:00h
AN: NS44A-03 INVITED     [Abstracts]
TI: Investigating Transient Heterogeneity in a Bioactive Hydrocarbon Plume Using GPR and PVPs
AU: * Devlin, J F
EM: jfdevlin@ku.edu
AF: Dept. of Geology, University of Kansas, Lindley Hall, rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AU: Schillig, P
EM: schillig@ku.edu
AF: Dept. of Geology, University of Kansas, Lindley Hall, rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AU: McGlashan, M
EM: mam10@ku.edu
AF: Dept. of Geology, University of Kansas, Lindley Hall, rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AU: Tsoflias, G
EM: tsoflias@ku.edu
AF: Dept. of Geology, University of Kansas, Lindley Hall, rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AU: Roberts, J
EM: jenrob@ku.edu
AF: Dept. of Geology, University of Kansas, Lindley Hall, rm. 120 1475 Jayhawk Blvd., Lawrence, KS 66045, United States
AB: Aquifer heterogeneity can place severe restrictions on deterministic modeling of contaminant fate and transport. One response to this is to collect geostatistical data so that multiple realizations of the aquifer can be simulated and probabilities of various transport scenarios estimated. However, both the deterministic and stochastic modeling approaches generally assume that the heterogeneities do not change in time. This assumption comes into question in a growing body of literature, mainly from laboratory studies, suggesting that heterogeneity in aquifers can be transient. In chemically active systems such as reactive barriers, or bioactive systems such as contaminant plumes, time dependent perturbations in flow have been documented. To date there are limited data investigating transient heterogeneity in contaminant plumes in the field. This research investigates the biological cases where the perturbations occur due to biomass growth, gas production, and chemical precipitate formation. A controlled gasoline release was conducted at one end of a sheet-pile alleyway in which groundwater was flowing at a constant rate of about 10 cm/day. Several meters downgradient of the release, the aquifer was instrumented with ORC wells, 5 PVP multilevel stands, and 6 GPR access tubes that were installed to a depth of about 5 m surrounding a section of the aquifer measuring about 2 m (along the flow direction) by 4 m (across the flow direction). Changes in the aquifer character following oxygen addition was monitored by repeatedly measuring groundwater velocites at 20 points across the plume, and by using GPR to obtain several tomographic images of the aquifer through time. The data suggest that indeed the aquifer responded to the oxygen additions with changes to the flow system. 1) assess the GPR response to microbial activity in a tank constructed to simulate the field aquifer, 2) assess the PVP responses in the same tank, and 3) correlate the above responses to microbial population changes in the simulated aquifer.
UR: http:www.people.ku.edu/~jfdevlin/Research.html
DE: 0416 Biogeophysics
DE: 0448 Geomicrobiology
DE: 0614 Biological effects
DE: 1829 Groundwater hydrology
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly