Natural Attenuation of MTBE at Laurel Bay, South Carolina

The occurrence of methyl tert-butyl ether (MTBE) in ground water at gasoline spill sites challenges the paradigm of natural attenuation remediation and our understanding of the impact of gasoline spills on the environment.

• The U.S. Geological Survey (USGS) has identified two important pathways that contribute to the natural attenuation of MTBE. The first is volatilization of MTBE from the spill source into the unsaturated zone, and the second is volatilization of MTBE from the water table down gradient from the source through the unsaturated zone. In both cases, MTBE volatilized to the unsaturated zone is subject to more efficient aerobic (with oxygen) biodegradation than MTBE in the anaerobic (without oxygen) saturated zone. These pathways are important, given MTBE's low degradation rates relative to BTEX (benzene, toluene, ethylbenzene, and zylene) compounds in the saturated zone. The USGS has developed methods to determine the magnitude of these natural attenuation pathways for MTBE.

• The USGS has shown that microorganisms indigenous to surface-water sediments are capable of rapidly degrading MTBE to carbon dioxide. This is the first significant microbial process that has been shown to degrade MTBE in natural environments. Previous studies (including our own) had suggested that MTBE was highly recalcitrant to biodegradation in ground-water systems. Based on these past studies, it was thought that MTBE-contaminated ground water might seep into surface water and accumulate, providing a source of exposure to humans and wildlife. However, this new result shows that MTBE is rapidly degraded in streambed sediments, and suggests that accumulation to environmentally harmful levels is unlikely.

References

Landmeyer, J.E., Chapelle, F.H., Bradley, P.M., Pankow, J.F., Church, C.D., and Tratnyek, P.G., 1998, Fate of MTBE relative to benzene in a gasoline-contaminated aquifer (1993-98): Ground Water Monitoring and Remediation, v. 18, no. 4, p. 93-102.

Bradley, P.M., J.E. Landmeyer, and F.H. Chapelle, 1999, Aerobic mineralization of MTBE and tert-butyl alcohol by stream-bed sediment microorganisms: Environmental Science and Technology, vol. 33, p. 1877-1879.

Related Headlines

• New Report Presents a Framework for Assessing the Sustainability of Monitored Natural Attenuation
• Challenging a Paradigm: MTBE Shown to Degrade to TBA Without Microorganisms
• Microorganisms Degrade MTBE Even at Winter Ground-Water Temperatures
• The Changing Face of Microbial Communities in Contaminant Plumes
• Using Oxygen to Enhance Biodegradation of Contaminants – Lessons Learned
• MTBE Biodegrades Naturally in Stream Sediments
• MTBE Can Degrade Naturally Without Oxygen
• How Do You Clean Up Gasoline Spills Naturally?

More Information

• Bibliography of Processes Affecting the Natural Attenuation of Fuel Oxygenates in Ground Water - Laurel Bay, South Carolina
• Oxygen-Release Compound Remediation Tests, project remediation related information

Petroleum Contamination Headlines

• Ground-Water Recharge Affects Fate of Petroleum Contaminant Plumes
• Predicting Plume Growth Rates - A Simple Method for Calculating Growth Rates of Petroleum Plumes
• Special Edition of "Environmental Geosciences" Explores Impacts of Oil and Gas Production on the Environment
• The Changing Face of Microbial Communities in Contaminant Plumes
• USGS Scientists Contribute to the Landmark " Treatise on Geochemistry "
• Improving Clean Up of Contamination from Oil and Gas Production
• A Unique Approach to Evaluating Natural Attenuation is Applied Worldwide
• How Do You Clean Up Gasoline Spills Naturally?
• Relying on Nature to Clean Up Contaminated Ground Water
• Natural Attenuation for Groundwater Remediation

Back to Research Highlights page