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Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1
Published on: April 16, 2018
Mechanisms of electron acceptor utilization: implications for simulating anaerobic biodegradation
M E Schreiber1, G R Carey, D T Feinstein
1Department of Geosciences, 4044 Derring Hall, Virginia Tech, Blacksburg, VA 24061, USA. mschreib@vt.edu
Journal of Contaminant Hydrology
|September 1, 2004
Summary
Simulating contaminant biodegradation requires understanding terminal electron acceptor processes (TEAPs). This study used a reactive transport model to simulate a BTEX plume, finding that sequential TEAP models struggle to explain observed redox product overlap, suggesting simultaneous processes or heterogeneity.
Area of Science:
- Environmental Science
- Geochemistry
- Hydrogeology
Background:
- Reactive transport models are crucial for simulating contaminant biodegradation.
- Terminal electron acceptor processes (TEAPs) dictate biodegradation rates.
- Sequential TEAP models often fail to accurately represent observed redox product distributions in contaminant plumes.
Purpose of the Study:
- To simulate biodegradation reactions within a reactive transport framework for a BTEX plume.
- To evaluate the mechanisms of TEAP utilization and their impact on contaminant mass loss.
- To investigate the causes of extensive overlap between Fe(II) and methane in contaminant plumes.
Main Methods:
- Utilized BioRedox-MT3DMS, a 3D multi-species reactive transport code.
- Simulated a BTEX plume and TEAP zones at a petroleum-contaminated field site.
- Performed sensitivity analyses on plume age, porosity, and biodegradation rate constants.
Main Results:
- BTEX mass loss was greatest under oxygen-reducing conditions, with similar contributions from Fe(III)-reducing, sulfate-reducing, and methanogenic conditions.
- Plume age was the most sensitive factor for BTEX biodegradation losses.
- Sequential TEAP models showed limited success in simulating the observed overlap of redox products.
Conclusions:
- Observed redox product overlap suggests simultaneous Fe(III) reduction and methanogenesis, or microscale heterogeneity in Fe(III) concentrations/mineral types.
- Accurate simulation of contaminant biodegradation requires a better understanding of TEAP mechanisms and plume heterogeneity.
- Further field, experimental, and modeling studies are needed to resolve the discrepancies in TEAP utilization and product overlap.
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