Long-Term Evolution of Biodegradation and Volatilization Rates in a Crude Oil-Contaminated Aquifer

Chaplin, Brian P.; Delin, G.N.; Baker, Ronald J.; Lahvis, Matthew A.

doi:10.1080/10889860290777594

Cited by 47 publications

(65 citation statements)

References 26 publications

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“…The crude oil constitutes a coupled reaction system in which methane (CH 4 ) is produced in the oil body at the water table and oxidized in the overlying vadose zone (Amos et al, 2005;Chaplin et al, 2002;Sihota and Mayer, 2012;Warren et al, 2014). Results from gas measurements taken in 1985, 1997, 2002, 2003, and 2009 show that methane from degradation of the subsurface oil diffuses upward and mixes with oxygen from the surface creating an active methanotrophic zone approximately half-way between the water table and land surface (Amos et al, 2005;Chaplin et al, 2002;Sihota and Mayer, 2012;Warren et al, 2014).The processes of methanogenesis and methane oxidation reflected in the Fig. 2 gas data are consistent with known reactions and microbial data from the oil body and overlying vadose zone.…”

Section: Site Descriptionmentioning

confidence: 99%

Relating subsurface temperature changes to microbial activity at a crude oil-contaminated site

Warren

Bekins

2015

Journal of Contaminant Hydrology

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Section: Site Descriptionmentioning

confidence: 99%

Relating subsurface temperature changes to microbial activity at a crude oil-contaminated site

Warren

Bekins

2015

Journal of Contaminant Hydrology

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“…The background dissolved oxygen concentration was 7.68 mg/l . Soil gas concentration measurements made by Hult et al (1991) and Chaplin et al (2002) have shown that biodegradation in the unsaturated zone depletes oxygen resulting in an anoxic unsaturated zone above the oil body. Therefore, it was assumed that there was no oxygen in the recharge water entering above the oil body and fully oxygenated recharge water in all other areas.…”

Section: Transport Initial and Boundary Conditionsmentioning

confidence: 99%

“…Chaplin et al (2002) have shown that significant biodegradation takes place in the unsaturated zone and capillary fringe prior to reaching the water table. Total gas hydrocarbon concentrations in the unsaturated zone immediately above the oil body have decreased significantly from 1985 -1997 suggesting relatively low hydrocarbon concentrations in the recharge water.…”

Section: Transport Initial and Boundary Conditionsmentioning

confidence: 99%

Inverse modeling of BTEX dissolution and biodegradation at the Bemidji, MN crude-oil spill site

Essaid

Cozzarelli

Eganhouse

et al. 2003

Journal of Contaminant Hydrology

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The U.S. Geological Survey (USGS) solute transport and biodegradation code BIOMOC was used in conjunction with the USGS universal inverse modeling code UCODE to quantify field-scale hydrocarbon dissolution and biodegradation at the USGS Toxic Substances Hydrology Program crude-oil spill research site located near Bemidji, MN. This inverse modeling effort used the extensive historical data compiled at the Bemidji site from 1986 to 1997 and incorporated a multicomponent transport and biodegradation model. Inverse modeling was successful when coupled transport and degradation processes were incorporated into the model and a single dissolution rate coefficient was used for all BTEX components. Assuming a stationary oil body, we simulated benzene, toluene, ethylbenzene, m,p-xylene, and o-xylene (BTEX) concentrations in the oil and ground water, respectively, as well as dissolved oxygen. Dissolution from the oil phase and aerobic and anaerobic degradation processes were represented. The parameters estimated were the recharge rate, hydraulic conductivity, dissolution rate coefficient, individual first-order BTEX anaerobic degradation rates, and transverse dispersivity. Results were similar for simulations obtained using several alternative conceptual models of the hydrologic system and biodegradation processes. The dissolved BTEX concentration data were not sufficient to discriminate between these conceptual models. The calibrated simulations reproduced the general large-scale evolution of the plume, but did not reproduce the observed small-scale spatial and temporal variability in concentrations. The estimated anaerobic biodegradation rates for toluene and o-xylene were greater than the dissolution rate coefficient. However, the estimated anaerobic biodegradation rates for benzene, ethylbenzene, and m,p-xylene were less than the dissolution rate coefficient. The calibrated model was used to determine the BTEX mass balance in the oil body and groundwater plume. This article is a U.S. government work, and is not subject to copyright in the United States.Dissolution from the oil body was greatest for compounds with large effective solubilities (benzene) and with large degradation rates (toluene and o-xylene). Anaerobic degradation removed 77% of the BTEX that dissolved into the water phase and aerobic degradation removed 17%. Although goodness-of-fit measures for the alternative conceptual models were not significantly different, predictions made with the models were quite variable. D

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“…Herkelrath [1999] calculated about 40% of the total north pool oil volume to be located in the unsaturated zone, which is not included in our groundwater model. Gas concentration data show that unsaturated zone oil biodegrades anaerobically [Chaplin et al, 2002;Amos et al, 2005], but model sensitivity tests indicate insignificant recharge contributions to secondary groundwater plumes compared to biodegradation at and below the water [Thorn and Aiken, 1998]; short-chain n-alkanes (C 11 H 25 ); and long-chain n-alkanes (C 15 H 32 ). The remaining unreactive oil pool is assigned a molar concentration calculated using an average molecular weight of 341 g/mol determined by Baedecker et al [2011].…”

Section: 1002/2015wr016964mentioning

confidence: 99%

Reactive transport modeling of geochemical controls on secondary water quality impacts at a crude oil spill site near Bemidji, MN

Bekins

Cozzarelli

et al. 2015

Water Resources Research

131

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Anaerobic biodegradation of organic amendments and contaminants in aquifers can trigger secondary water quality impacts that impair groundwater resources. Reactive transport models help elucidate how diverse geochemical reactions control the spatiotemporal evolution of these impacts. Using extensive monitoring data from a crude oil spill site near Bemidji, Minnesota (USA), we implemented a comprehensive model that simulates secondary plumes of depleted dissolved O 2 and elevated concentrations of Mn 21 , Fe 21 , CH 4 , and Ca 21 over a two-dimensional cross section for 30 years following the spill. The model produces observed changes by representing multiple oil constituents and coupled carbonate and hydroxide chemistry. The model includes reactions with carbonates and Fe and Mn mineral phases, outgassing of CH 4 and CO 2 gas phases, and sorption of Fe, Mn, and H 1 . Model results demonstrate that most of the carbon loss from the oil (70%) occurs through direct outgassing from the oil source zone, greatly limiting the amount of CH 4 cycled down-gradient. The vast majority of reduced Fe is strongly attenuated on sediments, with most (91%) in the sorbed form in the model. Ferrous carbonates constitute a small fraction of the reduced Fe in simulations, but may be important for furthering the reduction of ferric oxides. The combined effect of concomitant redox reactions, sorption, and dissolved CO 2 inputs from source-zone degradation successfully reproduced observed pH. The model demonstrates that secondary water quality impacts may depend strongly on organic carbon properties, and impacts may decrease due to sorption and direct outgassing from the source zone.

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Long-Term Evolution of Biodegradation and Volatilization Rates in a Crude Oil-Contaminated Aquifer

Cited by 47 publications

References 26 publications

Relating subsurface temperature changes to microbial activity at a crude oil-contaminated site

Relating subsurface temperature changes to microbial activity at a crude oil-contaminated site

Inverse modeling of BTEX dissolution and biodegradation at the Bemidji, MN crude-oil spill site

Reactive transport modeling of geochemical controls on secondary water quality impacts at a crude oil spill site near Bemidji, MN

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