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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Electrical Resistivity Imaging For Long-Term Autonomous Monitoring Of Hydrocarbon Degradation: Lessons From The Deepwater Horizon Oil Spill, Jeffrey W. Heenan, Lee D. Slater, Dimitrios Ntarlagiannis, Estella A. Atekwana, Babu Z. Fathepure, Sonal Dalvi, Cameron Ross, D. Dale Werkema, Eliot A. Atekwana
Electrical Resistivity Imaging For Long-Term Autonomous Monitoring Of Hydrocarbon Degradation: Lessons From The Deepwater Horizon Oil Spill, Jeffrey W. Heenan, Lee D. Slater, Dimitrios Ntarlagiannis, Estella A. Atekwana, Babu Z. Fathepure, Sonal Dalvi, Cameron Ross, D. Dale Werkema, Eliot A. Atekwana
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Conceptual models for the geophysical responses associated with hydrocarbon degradation suggest that the long-term evolution of an oil plume will result in a more conductive anomaly than the initial contamination. In response to the Deepwater Horizon (DH) oil spill into the Gulf of Mexico in 2010, an autonomous resistivity monitoring system was deployed on Grand Terre, Louisiana, in an attempt to monitor natural degradation processes in hydrocarbon-impacted beach sediments of this island. A 48-electrode surface array with a 0.5-m spacing was installed to obtain twice-daily images of the resistivity structure of the shallow subsurface impacted by oil. Over the course …
Spectral Induced Polarization (Sip) Response Of Biodegraded Oil In Porous Media, Gamal Z. Abdel Aal, Estella A. Atekwana
Spectral Induced Polarization (Sip) Response Of Biodegraded Oil In Porous Media, Gamal Z. Abdel Aal, Estella A. Atekwana
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Laboratory experiments were conducted to investigate the effect of different oil saturation (0.2- 0.8), wetting conditions (water-wet and oil-wet), and the addition of asphaltene on the spectral induced polarization (SIP) response of biodegraded and fresh crude oil in sand columns. In the water-wet case, no significant differences were observed for both the fresh and biodegraded oil and both displayed an increase in the magnitude of the phase (φ) and decrease in the magnitudes of the real (σ′) and imaginary (σ″) conductivity components with increasing oil saturation. In this instance the SIP response is most likely controlled by the conduction and …
Microbial Nanowires: Is The Subsurface "Hardwired"?, Dimitrios Ntarlagiannis, Estella A. Atekwana, Eric A. Hill, Yuri A. Gorby
Microbial Nanowires: Is The Subsurface "Hardwired"?, Dimitrios Ntarlagiannis, Estella A. Atekwana, Eric A. Hill, Yuri A. Gorby
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The Earth's shallow subsurface results from integrated biological, geochemical, and physical processes. Methods are sought to remotely assess these interactive processes, especially those catalysed by micro-organisms. Using saturated sand columns and the metal reducing bacterium Shewanella oneidensis MR-1, we show that electrically conductive appendages called bacterial nanowires are directly associated with electrical potentials. No significant electrical potentials were detectable in columns inoculated with mutant strains that produced non-conductive appendages. Scanning electron microscopy imaging revealed a network of nanowires linking cells-cells and cells to mineral surfaces, "hardwiring" the entire length of the column. We hypothesize that the nanowires serve as conduits …
The Microbial Community Structure In Petroleum-Contaminated Sediments Corresponds To Geophysical Signatures, Jonathan P. Allen, Estella A. Atekwana, Eliot A. Atekwana, Joseph W. Duris, D. Dale Werkema, Silvia Rossbach
The Microbial Community Structure In Petroleum-Contaminated Sediments Corresponds To Geophysical Signatures, Jonathan P. Allen, Estella A. Atekwana, Eliot A. Atekwana, Joseph W. Duris, D. Dale Werkema, Silvia Rossbach
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The interdependence between geoelectrical signatures at underground petroleum plumes and the structures of subsurface microbial communities was investigated. For sediments contaminated with light non-aqueous-phase liquids, anomalous high conductivity values have been observed. Vertical changes in the geoelectrical properties of the sediments were concomitant with significant changes in the microbial community structures as determined by the construction and evaluation of 16S rRNA gene libraries. DNA sequencing of clones from four 16S rRNA gene libraries from different depths of a contaminated field site and two libraries from an uncontaminated background site revealed spatial heterogeneity in the microbial community structures. Correspondence analysis showed …
Microbial Growth And Biofilm Formation In Geologic Media Is Detected With Complex Conductivity Measurements, Caroline A. Davis, Estella A. Atekwana, Eliot A. Atekwana, Lee D. Slater, Silvia Rossbach, Melanie R. Mormile
Microbial Growth And Biofilm Formation In Geologic Media Is Detected With Complex Conductivity Measurements, Caroline A. Davis, Estella A. Atekwana, Eliot A. Atekwana, Lee D. Slater, Silvia Rossbach, Melanie R. Mormile
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Complex conductivity measurements (0.1-1000 Hz) were obtained from biostimulated sand-packed columns to investigate the effect of microbial growth and biofilm formation on the electrical properties of porous media. Microbial growth was verified by direct microbial counts, pH measurements, and environmental scanning electron microscope imaging. Peaks in imaginary (interfacial) conductivity in the biostimulated columns were coincident with peaks in the microbial cell concentrations extracted from sands. However, the real conductivity component showed no discernible relationship to microbial cell concentration. We suggest that the observed dynamic changes in the imaginary conductivity (σ″) arise from the growth and attachment of microbial cells and …
In-Situ Apparent Conductivity Measurements And Microbial Population Distribution At A Hydrocarbon-Contaminated Site, Estella A. Atekwana, D. Dale Werkema, Joseph W. Duris, Silvia Rossbach, Eliot A. Atekwana, William A. Sauck, Daniel P. Cassidy, Jay Means, Franklyn D. Legall
In-Situ Apparent Conductivity Measurements And Microbial Population Distribution At A Hydrocarbon-Contaminated Site, Estella A. Atekwana, D. Dale Werkema, Joseph W. Duris, Silvia Rossbach, Eliot A. Atekwana, William A. Sauck, Daniel P. Cassidy, Jay Means, Franklyn D. Legall
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
We investigated the bulk electrical conductivity and microbial population distribution in sediments at a site contaminated with light nonaqueous-phase liquid (LNAPL). The bulk conductivity was measured using in-situ vertical resistivity probes; the most probable number method was used to characterize the spatial distribution of aerobic heterotrophic and oil-degrading microbial populations. The purpose of this study was to assess if high conductivity observed at aged LNAPL-impacted sites may be related to microbial degradation of LNAPL. The results show higher bulk conductivity coincident with LNAPL-impacted zones, in contrast to geoelectrical models that predict lower conductivity in such zones. The highest bulk conductivity …
Investigating The Geoelectrical Response Of Hydrocarbon Contamination Undergoing Biodegradation, D. Dale Werkema, Estella A. Atekwana, Anthony L. Endres, William August Sauck, Daniel P. Cassidy
Investigating The Geoelectrical Response Of Hydrocarbon Contamination Undergoing Biodegradation, D. Dale Werkema, Estella A. Atekwana, Anthony L. Endres, William August Sauck, Daniel P. Cassidy
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
A newly proposed geoelectrical model for hydrocarbon contaminated sites predicts high conductivities coincident with the contaminated zone as opposed to the traditionally accepted low conductivity. The model attributes the high conductivities to mineral weathering resulting from byproducts of microbial redox processes. To evaluate this conductive model, in situ vertical conductivity measurements were acquired from a light non-aqueous phase liquid (LNAPL) contaminated site. The results showed high conductivities coincident with the zone of contamination and within the smear zone influenced by seasonal water table fluctuations. We infer this zone as an active zone of biodegradation and suggest significant microbial degradation under …