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Perchlorate natural attenuation in a riparian zone
Robert C Borden1, Sheri L Knox, M Tony Lieberman
1a Solutions-IES, Inc. , Raleigh , North Carolina , USA.
Summary
Natural flushing reduces perchlorate in aerobic aquifers, while biodegradation occurs in organic-rich littoral zones. This study documents perchlorate
Area of Science:
- Environmental Science
- Hydrogeology
- Microbiology
Background:
- Perchlorate contamination poses risks to water resources.
- Understanding natural attenuation processes is crucial for effective remediation strategies.
Purpose of the Study:
- To document the natural attenuation of perchlorate in a shallow alluvial aquifer.
- To investigate the mechanisms and rates of perchlorate degradation.
- To identify conditions supporting perchlorate biodegradation.
Main Methods:
- Field monitoring of perchlorate concentrations and groundwater flow.
- Laboratory microcosm experiments to determine degradation rates.
- Quantitative Polymerase Chain Reaction (qPCR) to assess microbial populations.
Main Results:
- No perchlorate biodegradation observed in the aerobic aquifer.
- Groundwater flushing effectively reduces perchlorate concentrations over time.
- Rapid perchlorate attenuation occurs in organic-rich littoral zones.
- Elevated perchlorate-degrading bacteria populations identified in the littoral zone.
- Perchlorate degradation rates in groundwater consistent with laboratory findings.
Conclusions:
- Natural flushing is a key process for perchlorate attenuation in aerobic aquifer zones.
- Biodegradation in littoral zones significantly contributes to perchlorate removal.
- Perchlorate-degrading microorganisms can thrive in moderately oxidizing conditions.
- The findings support the potential for natural attenuation to meet cleanup criteria.
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