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| Title: | In-situ apparent conductivity measurements and microbial population distribution at a hydrocarbon-contaminated site |
| Author (s): | Atekwana, Estella A. Werkema, D. Dale Duris, Joseph W. Rossbach, Silvia Atekwana, Eliot A. Sauck, William A. Cassidy, Daniel P. Means, Jay Legall, Franklyn D. |
| Department/Lab Affiliations: | Geological Sciences & Engineering |
| Keywords: | Soil pollution biochemistry contamination electrical conductivity measurement geochemistry microorganisms sediments |
| Issue Date: | 2004 |
| Publisher: | Society of Exploration Geophysicists |
| Citation: | Atekwana, Estella A., D. Dale Werkema, Joseph W. Duris, Silvia Rossbach, Eliot A. Atekwana, William A. Sauk, Daniel P. Cassidy, Jay Means, and Franklyn D. Legall. "In-situ Apparent Conductivity Measurements and Microbial Population Distribution at a Hydrocarbon-Contaminated Site." Geophysics, vol. 69, no. 1, 2004. |
| Abstract: | 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 was observed to be associated with zones impacted by residual and free LNAPL. Data from bacteria enumeration from sediments close to the resistivity probes show that oil-degrading microbes make up a larger percentage (5–55%) of the heterotrophic microbial community at depths coincident with the higher conductivity compared to ~5% at the uncontaminated location. The coincidence of a higher percentage of oil-degrading microbial populations in zones of higher bulk conductivity suggests that the higher conductivity in these zones may result from increased fluid conductivity related to microbial degradation of LNAPL, consistent with geochemical studies that suggest that intrinsic biodegradation is occurring at the site. The findings from this study point to the fact that biogeochemical processes accompanying biodegradation of contaminants can potentially alter geoelectrical properties of the subsurface impacted media. |
| Type: | Article - Journal text |
| In Title: | Geophysics |
| Copyright Notice: | This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. Pre-print: archiving status unclear; Post-print: author can archive; FULL COPYRIGHT INFORMATION: |
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| title | In-situ apparent conductivity measurements and microbial population distribution at a hydrocarbon-contaminated site |
| contributor.author | Atekwana, Estella A. |
| contributor.author | Werkema, D. Dale |
| contributor.author | Duris, Joseph W. |
| contributor.author | Rossbach, Silvia |
| contributor.author | Atekwana, Eliot A. |
| contributor.author | Sauck, William A. |
| contributor.author | Cassidy, Daniel P. |
| contributor.author | Means, Jay |
| contributor.author | Legall, Franklyn D. |
| contributor.deptlab | Geological Sciences & Engineering |
| contributor.sponsor | American Chemical Society Petroleum Research Fund |
| contributor.sponsor | National Science Foundation |
| subject | Soil pollution |
| subject | biochemistry |
| subject | contamination |
| subject | electrical conductivity measurement |
| subject | geochemistry |
| subject | microorganisms |
| subject | sediments |
| date.issued | 2004 |
| publisher | Society of Exploration Geophysicists |
| identifier.citation | Atekwana, Estella A., D. Dale Werkema, Joseph W. Duris, Silvia Rossbach, Eliot A. Atekwana, William A. Sauk, Daniel P. Cassidy, Jay Means, and Franklyn D. Legall. "In-situ Apparent Conductivity Measurements and Microbial Population Distribution at a Hydrocarbon-Contaminated Site." Geophysics, vol. 69, no. 1, 2004. |
| identifier.pub.URI | |
| description.abstract | 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 was observed to be associated with zones impacted by residual and free LNAPL. Data from bacteria enumeration from sediments close to the resistivity probes show that oil-degrading microbes make up a larger percentage (5–55%) of the heterotrophic microbial community at depths coincident with the higher conductivity compared to ~5% at the uncontaminated location. The coincidence of a higher percentage of oil-degrading microbial populations in zones of higher bulk conductivity suggests that the higher conductivity in these zones may result from increased fluid conductivity related to microbial degradation of LNAPL, consistent with geochemical studies that suggest that intrinsic biodegradation is occurring at the site. The findings from this study point to the fact that biogeochemical processes accompanying biodegradation of contaminants can potentially alter geoelectrical properties of the subsurface impacted media. |
| type | Article - Journal |
| type.DCMIType | text |
| rights | This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. |
| rights | Pre-print: archiving status unclear; Post-print: author can archive; |
| rights.URI | |
| relation.isPartOf | Geophysics |
| date.available | 2008-07-29T18:12:55Z |
| identifier.persist.URI |