MTBE Fate at Natural Oxic/Anoxic Interfaces

The influence of oxic/anoxic interfaces on the biodegradation of methyl tert-butyl ether (MTBE) was investigated at the Laurel Bay research site in South Carolina. Significant biodegradation was observed where anoxic, MTBE-contaminated ground water discharged to a concrete-lined ditch. In the anoxic portion of the aquifer adjacent to the ditch, concentrations of MTBE were near 1 mg/L. Directly below the ditch where DO concentrations exceeded 1.0 mg/L to a depth of 1.5 meters, MTBE concentrations decreased to less than 1 µg/L prior to discharge. Samples of the microbial biofilm present at the oxic/anoxic interface rapidly degraded [U-¹⁴C] MTBE to ¹⁴C-CO₂ in laboratory liquid culture studies without the appearance of intermediate compounds or cell growth. Fatty acid methyl ester and denaturing gradient gel electrophoresis analysis of the liquid culture indicates a community of Bacillus spp. in the biofilm that may play an important role in the observed MTBE biodegradation at the oxic/anoxic interface. These results indicate that natural oxic/anoxic interfaces in hydrologic systems play an important role in the natural attenuation of MTBE plumes. A pdf file is available for download (1.1Mb).

More Information

• MTBE Can Degrade Naturally Without Oxygen
• MTBE Biodegrades Naturally in Stream Sediments

Available Publications

• Bradley, P.M., Chapelle, F.H. and Landmeyer, J.E., 2001, MTBE mineralization in surface-water sediment microcosms under denitrifying conditions: Applied and Environmental Microbiology, v. 67, no. 4., p. 1975-1978. (This paper provides the first published evidence of the degradation of MTBE in anoxic conditions)
• Bradley, P.M., Landmeyer, J.E., and Chapelle, F.H., 2001, Widespread Potential for Microbial MTBE Degradation in Surface-Water Sediments: Environmental Science and Technology, v. 35, no. 4, p. 658-662.
• Landmeyer, J.E., Chapelle, F.H., Herlong, H.H., and Bradley, P.M., 2001, Methyl tert-butyl ether biodegradation by indigenous aquifer microorganisms under natural and artificial oxic conditions: Environmental Science and Technology, v. 35, n. 6, p. 1118-1126

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