HR: 0800h
AN: H21A-0998    [Abstracts]
TI: Single-Well Push-Pull Tests for Evaluating In Situ TCE, cis-DCE, and trans-DCE Cometabolism by Toluene-Utilizing Microorganisms
AU: * Semprini, L
EM: lewis.semprini@oregonstate.edu
AF: Oregon State University, Department of Civil, Construction, and Environmental Engineering, Corvallis, OR 97331 United States
AU: Azizian, M
EM: mohammad.azizian@oregonstate.edu
AF: Oregon State University, Department of Civil, Construction, and Environmental Engineering, Corvallis, OR 97331 United States
AU: Istok, J D
EM: jack.istok@oregonstate.edu
AF: Oregon State University, Department of Civil, Construction, and Environmental Engineering, Corvallis, OR 97331 United States
AB: Single-well-push-pull tests were performed to assess the feasibility of in situ aerobic cometabolism of chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethylene (TCE) and cis-1,2-dichloroethylene (cis-DCE), by toluene-grown microorganisms. The tests were performed in the saturated zone at Fort Lewis, Washington, which is contaminated with TCE and cis-DCE. The tests assessed the heterogeneity of the indigenous microorganisms towards toluene utilization and CAH transformation. The tests were conducted in two multi-level monitoring wells at two different depths. Transport characteristics of the dissolved solutes were compared using bromide as a conservative tracer. Toluene utilization was evaluated by observing repeated uptake under natural gradient flow conditions and during push-pull activity tests. For the push-pull activity tests, the injected solution was amended with the substrates of interest, and after injection was permitted to reside in the formation for 24 hours and then extracted. Toluene utilization was indicated by decreases in concentration, when normalized to bromide as a conservative tracer, dissolved oxygen uptake, and the production of ortho-cresol as an intermediate oxidation product. Isobutene added to the injected groundwater was transformed to isobutene oxide, indicating that microorganisms that express an ortho-monooxygenase were stimulated. Similar rates of toluene utilization, isobutene, cis-DCE, and trans-DCE transformation were achieved at the four different locations tested. Rate estimates obtained in the 24-hour activity tests were similar to those achieved in the 50-hour natural gradient tests. The results indicated that at the four locations tested, there was little difference in the rates of toluene utilization and cometabolic transformation.
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting