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Widespread potential for microbial MTBE degradation in surface-water sediments.
P M Bradley1, J E Landmeyer, F H Chapelle
1U.S. Geological Survey, 720 Gracern Road, Suite 129, Columbia, South Carolina 29210-7651, USA. pbradley@usgs.gov
Environmental Science & Technology
|May 15, 2001
Summary
Microbial communities in U.S. stream and lake sediments can break down methyl-tert-butyl ether (MTBE). This natural degradation ability is widespread, suggesting a significant environmental sink for MTBE in surface waters.
Area of Science:
- Environmental microbiology
- Bioremediation
- Organic geochemistry
Background:
- Methyl-tert-butyl ether (MTBE) is a fuel oxygenate commonly found in surface waters.
- Understanding MTBE biodegradation pathways is crucial for assessing its environmental fate.
Purpose of the Study:
- To investigate the capacity of indigenous microorganisms in stream and lake bed sediments to mineralize MTBE.
- To determine if prior MTBE exposure influences biodegradation potential.
- To explore the relationship between sediment characteristics and MTBE mineralization rates.
Main Methods:
- Sediment samples were collected from 11 diverse U.S. sites.
- Microbial mineralization of [U-14C]MTBE to 14CO2 was measured over 50 days.
- Sediment grain size distribution was analyzed.
- Statistical correlations between 14CO2 recovery and sediment properties were calculated.
Main Results:
- Significant MTBE mineralization (15-66% over 50 days) was observed across all tested sediments.
- No significant difference in mineralization was found between previously contaminated and uncontaminated sites.
- A strong inverse correlation (p < 0.001) existed between 14CO2 recovery and silt/clay content (<0.125 mm).
Conclusions:
- Indigenous microorganisms in U.S. stream and lake sediments possess a widespread and innate ability to degrade MTBE under aerobic conditions.
- Aerobic microbial processes in bed sediments represent a potentially significant environmental sink for MTBE.
- Sediment grain size, specifically silt and clay content, influences the efficiency of MTBE biodegradation.