Radiocarbon and Stable Carbon Isotope Analysis to Confirm Petroleum Natural Attenuation in the Vadose Zone

Coffin, Richard B.; Pohlman, John W.; Grabowski, K. S.; Knies, D. L.; Plummer, Rebecca E.; Magee, Robert W.; Boyd, Thomas J.

doi:10.1080/15275920801888335

Cited by 13 publications

(20 citation statements)

References 40 publications

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“…At locations where sediments have high organic-carbon content, fermentation may produce higher concentrations of both CH 4 and CO 2 , which may result in a landfill-or sewage-like signature. Partial oxidation of subsurface petroleum contaminants may produce elevated CH 4 and CO 2 concentrations (Coffin et al, 2008;Revesz et al, 1995). The influence of partial oxidation may be evident where electron acceptors, such as oxygen, and indigenous bacteria promote mineralization of hydrocarbons to CO 2 and CH 4 , resulting in a bacterial-like geo-gas signature.…”

Section: Inorganic and Organic Gas Compositionmentioning

confidence: 99%

Forensic Geo-Gas Investigation of Methane: Characterization of Sources within an Urban Setting

O’Sullivan

Min

Bilyk

et al. 2010

Environmental Forensics

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Section: Inorganic and Organic Gas Compositionmentioning

confidence: 99%

Forensic Geo-Gas Investigation of Methane: Characterization of Sources within an Urban Setting

O’Sullivan

Min

Bilyk

et al. 2010

Environmental Forensics

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“…It is thus possible to estimate the proportion of the entire CO 2 pool (respired carbon) attributable to the contaminant. Using solely this proportion, fossil-hydrocarbon or industrial chemical oxidation at field sites has been confirmed [7][8][9][10][11][12][13] . This proportion of contaminant derived CO 2 can then be coupled with total CO 2 mineralization rate (all CO 2 collected per unit time and volume) to determine intrinsic contaminant mineralization rate.…”

Section: Introductionmentioning

confidence: 99%

“…Within the plume or at the fringes, contaminant-derived CO 2 will have 0% modern carbon. CO 2 from NOM sources and CO 2 derived from fossil sources can be distinguished with a two end-member mixing model 11 . It is thus possible to estimate the proportion of the entire CO 2 pool (respired carbon) attributable to the contaminant.…”

Section: Introductionmentioning

confidence: 99%

“…Because very distinct isotopic signatures are available in carbon-based contaminants, carbon isotopes have been recently applied to understanding contaminant attenuation processes at field sites [5][6][7][8][9][10][11][12][13] . Stable carbon isotopes can be used to determine if a source is attenuating based on Rayleigh distillation kinetics (c.f.…”

Section: Introductionmentioning

confidence: 99%

“…The technique described here relies on the observation that any CO 2 generated from a fossil derived contaminant will be devoid of 14 C while CO 2 generated from microorganisms degrading NOM will contain easily-measurable amounts of 14 C. Measuring 14 CO 2 also allows one to directly link full contaminant degradation (i.e., mineralization) to a harmless end product. 14 CO 2 analysis has been used to follow fossil fuel-derived contaminant degradation products [7][8][9][10][11][12][13] . This is due to the analytical resolution between end members (fossil and contemporary) which is roughly 1,100 parts per thousand (‰).…”

Section: Introductionmentioning

confidence: 99%

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Measuring Carbon-based Contaminant Mineralization Using Combined CO<sub>2</sub> Flux and Radiocarbon Analyses

Boyd

Montgomery

Cuenca

et al. 2016

JoVE

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Carbon isotope forensics for methane source identification

Coffin

Mueller

2020

Remediation Journal

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Methane (CH4) in ecosystems originates from ancient petroleum formed deep within the earth and/or via microbial fermentation of organic carbon and subsequent reduction of carbon dioxide (CO2). Given the complexity of different ecosystems, origins of CH4 present can be difficult to determine. This issue was realized in a situation where an antimethanogenic in situ chemical reduction (ISCR) remedial amendment containing organic carbon plus zero‐valent iron was applied to treat chlorinated solvents in groundwater at a former dry cleaner facility. The technology rapidly and effectively reduced the concentration of tetrachloroethene in groundwater thus meeting project goals without the stoichiometric accumulation of catabolites such as trichloroethene (TCE), cis‐1,2‐dichloroethene, or vinyl chloride and without excessive methanogenesis (e.g., <2 mg/L) in the treated area. However, approximately 9 months after treatment, increased levels of CH4 (from 5 to 10 mg/L) were observed downgradient from the treated area. The applied remedial amendment contained approximately 60% (weight basis) fermentation organic carbon and was therefore a potential source of this CH4. However, there was <500 mg/L total organic carbon in groundwater emanating from the upgradient treatment area which was unlikely sufficient to produce that much CH4. Moreover, the soil gas also contained benzene, toluene, ethylbenzene, and xylenes and other gasoline constituents. These data suggested that the presence of three gasoline/diesel underground storage tanks that were previously closed in place with no active remediation performed could be the source of elevated CH4. Thirdly, there were sewer lines, utilities, multiple gasoline stations, and industrial activities in the immediate area. With an initial assumption that CH4 source(s) could include the ISCR amendment over stimulation of production, gasoline sourced CH4 from nearby leaking lines, or sewage from local fractured pipes, carbon isotope analyses—radiocarbon (Δ14C) and stable carbon (δ13C)—were coupled with CH4 and CO2 concentration data from groundwater samples to determine the origin of respired carbon. The δ13C range for carbon sources respired in the process would be approximately −26.5‰ to −33.0‰ for the ISCR amendment and total petroleum hydrocarbons (TPH) residuals, respectively. Δ14C is approximately 0‰ and −999‰ for the ISCR amendment (young carbon) and TPH (old carbon), respectively. The isotopic signature of respired gasses confirmed that elevated CH4 downgradient of the treated area originated primarily from sewer gasses (or fermentation of liquids released from sewer lines). This study provides an overview of the capability to apply carbon isotope geochemistry to confirmation of remedial protocols and sources of anthropogenic carbon pools that conclusively identify the origin of CH4 in a complex ecosystem undergoing a remedial action.

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Radiocarbon and Stable Carbon Isotope Analysis to Confirm Petroleum Natural Attenuation in the Vadose Zone

Cited by 13 publications

References 40 publications

Forensic Geo-Gas Investigation of Methane: Characterization of Sources within an Urban Setting

Forensic Geo-Gas Investigation of Methane: Characterization of Sources within an Urban Setting

Measuring Carbon-based Contaminant Mineralization Using Combined CO<sub>2</sub> Flux and Radiocarbon Analyses

Carbon isotope forensics for methane source identification

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