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South-Central Section–40th Annual Meeting (6–7 March 2006)

Paper No. 6
Presentation Time: 4:30 PM

ASSESSMENT OF IN SITU BIODEGRADATION POTENTIAL OF MTBE USING 13C-LABELED MTBE AND BIO-SEP® BEADS


BUSCH-HARRIS, Jennifer L.1, SUBLETTE, Kerry L.2, ROBERTS, Kenneth P.3, JENNINGS, Eleanor4, PEACOCK, Aaron5, WHITE, David C.5, DAVIS, Greg6, HOLMES, William7, YANG, Xiaomin8 and KOLHATKAR, Arati9, (1)Ctr for Applied Biogeosciences, Dept of Biological Science, Univ of Tulsa, 600 South College Ave, Tulsa, OK 74112, (2)Ctr of Applied Biogeosciences, Dept of Chemical Engineering, Univ of Tulsa, 600 South College Ave, Tulsa, OK 74104, (3)Dept of Chemistry and Biochemistry, Univ of Tulsa, 600 South College Ave, Tulsa, OK 74104, (4)Ctr for Applied Biogeosciences, Dept of Geoscience, Univ of Tulsa, 600 South College Ave, Tulsa, OK 74104, (5)Ctr for Biomarker Analysis, Univ of Tennessee, 10515 Research Dr, Suite 300, Knoxville, TN 37932, (6)Microbial Insights, Inc, 2340 Stock Creek Blvd, Rockford, TN 57853, (7)College of Natural Resources and the Environment, Univ of Michigan, 440 Church Street, G540B Dana, Ann Arbor, MI 48109-1041, (8)Environmental Technology, Atlantic Richfield Company, Mail Code 2S, 28100 Torch Parkway, Warrenville, IL 60555, (9)RM Environmental Technology, Atlantic Richfield, 501 Westlake Pk Blvd, 20.104B, Houston, TX 77079, jennifer-busch@utulsa.edu

Evidence of microbial MTBE degradation has been indicated by laboratory microcosm studies and observations of in situ isotopic fractionation.  However, no in situ study has directly proven the biological depletion of MTBE.  The objective of this study was to demonstrate anaerobic, in situ biodegradation of MTBE and to investigate the responsible microorganisms.  Bio-Traps containing Bio-Sep® beads preloaded with 13C-labeled MTBE (16% 13C-MTBE and 84% 12C-MTBE) were deployed into a gas oxygenate-contaminated aquifer in California.  After 30 days, the Bio-Traps were retrieved and analyzed.  The residual pool of MTBE was extracted and analyzed by GC-MS.  MTBE concentrations decreased by 90% and the 13C/12C ratio increased.  The GC-c-IRMS analysis of total lipid fatty acids showed enrichment of one signature fatty acid with d13C of 101.9.  These data suggested biological degradation of the target compound and incorporation of the isotope into the biomass.  The experiment was repeated in an Illinois aquifer, with modifications. MTBE concentrations were again depleted by 94% and the 13C/12C-MTBE ratio increased significantly in the residual pool of MTBE that remained adsorbed within the Bio-Traps.  Additionally, 13C-MTBE Bio-Traps baited with sulfate showed a significant increase in both d13C and total biomass.  This study is significant because it demonstrates that intrinsic biodegradation of MTBE occurs in anaerobic, in situ aquifer conditions.

Session No. 4

Geochemistry and Environmental Geology
Monday, 6 March 2006: 2:50 PM-5:10 PM
Geological Society of America Abstracts with Programs. Vol. 38, No. 1, p.10
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