U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting Charleston South Carolina March 8-12, 1999--Volume 3 of 3--Subsurface Contamination From Point Sources, Water-Resources Investigations Report 99-4018C

Aerobic Mineralization of MTBE and t-Butanol by Stream-Bed-Sediment Microorganisms

Paul M. Bradley, James E. Landmeyer and Francis H. Chapelle

ABSTRACT

Microorganisms indigenous to the bed sediments of two streams receiving seepage of gasoline-contaminated ground water demonstrated significant mineralization of the fuel oxygenates, methyl-t-butyl ether (MTBE) and t-butyl alcohol (TBA). Up to 73% of [U-¹⁴C] MTBE and 84% of [U-¹⁴C] TBA were degraded to ¹⁴CO₂ under mixed aerobic/anaerobic conditions. No significant mineralization was observed under strictly anaerobic conditions. The results indicate that, under the mixed aerobic/anaerobic conditions characteristic of stream bed sediments, microbial processes may provide a significant environmental sink for MTBE and TBA delivered to surface-water bodies by contaminated ground-water or by atmospheric deposition.