Toxic Substances Hydrology Program
Research Projects -- Oxygenated Fuel -- Laurel Bay, South Carolina, Site
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).