Multiple‐Process Assessment for a Chlorinated‐Solvent Plume

Eberts, Sandra M.; Harvey, G.; Jones, Sonya A.; Beckman, S. W.

doi:10.1002/047127304x.ch19

Cited by 13 publications

(7 citation statements)

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“…Therefore, relatively high cDCE/TCE ratio in the core from tree TX11 may reflect subsurface dechlorination. This is in agreement with previous work at this site that showed a general relation between TCE/cDCE ratios in ground water and stem tissue in a mature cottonwood relative to immature cottonwoods at this site (Eberts et al 2003). In addition, Eberts et al (2003) note that, north of Farmer's Branch, where the depth to ground water is ~3 m or less, delivery of dissolved organic carbon to the aquifer is sufficient to initiate reductive declorination of TCE.…”

Section: Carswell Golf Coursesupporting

confidence: 93%

“…This is in agreement with previous work at this site that showed a general relation between TCE/cDCE ratios in ground water and stem tissue in a mature cottonwood relative to immature cottonwoods at this site (Eberts et al 2003). In addition, Eberts et al (2003) note that, north of Farmer's Branch, where the depth to ground water is ~3 m or less, delivery of dissolved organic carbon to the aquifer is sufficient to initiate reductive declorination of TCE. Consistent with this, the cDCE/TCE ratios in cores from trees TX4 and TX6 growing north of Farmer's Branch where the shallow ground water was ~1 m deep were higher than in all other trees except the previously mentioned tree TX11.…”

Section: Carswell Golf Coursesupporting

confidence: 93%

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Ground Water Chlorinated Ethenes in Tree Trunks: Case Studies, Influence of Recharge, and Potential Degradation Mechanism

Vroblesky

Clinton

Vose

et al. 2004

Groundwater Monitoring Rem

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Trichloroethene (TCE) was detected in cores of trees growing above TCE‐contaminated ground at three sites: the Carswell Golf Course in Texas, Air Force Plant PJKS in Colorado, and Naval Weapons Station Charleston in South Carolina. This was true even when the depth to water was 7.9 m or when the contaminated aquifer was confined beneath ∼3 m of clay. Additional ground water contaminants detected in the tree cores were cis–1,2‐dichloroethene at two sites and tetrachloroethene at one site. Thus, tree coring can be a rapid and effective means of locating shallow subsurface chlorinated ethenes and possibly identifying zones of active TCE dechlorination. Tree cores collected over time were useful in identifying the onset of ground water contamination. Several factors affecting chlorinated ethene concentrations in tree cores were identified in this investigation. The factors include ground water chlorinated ethene concentrations and depth to ground water contamination. In addition, differing TCE concentrations around the trunk of some trees appear to be related to the roots deriving water from differing areas. Opportunistic uptake of infiltrating rainfall can dilute prerain TCE concentrations in the trunk. TCE concentrations in core headspace may differ among some tree species. In some trees, infestation of bacteria in decaying heartwood may provide a TCE dechlorination mechanism within the trunk.

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Section: Carswell Golf Coursesupporting

confidence: 93%

Section: Carswell Golf Coursesupporting

confidence: 93%

Ground Water Chlorinated Ethenes in Tree Trunks: Case Studies, Influence of Recharge, and Potential Degradation Mechanism

Vroblesky

Clinton

Vose

et al. 2004

Groundwater Monitoring Rem

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“…Eberts et al (1999) used sap‐flow and ground water flow models to estimate that a 20% decrease in mass flux may be attributable to transpiration directly from the aquifer (uptake) once the plantations reach their transpiration potential. These combined results suggest that, after 6 years, in situ biodegradation is becoming the dominant process that contributes to the reduction in the mass flux of TCE across the site, whereas transpiration directly from the aquifer was the dominant process during the first 3 years after planting (Eberts et al 2003). The extreme thinness of the aquifer under study (∼1.5 m of saturated thickness along the modeled flowpath) may have influenced the degree to which changes in ground water chemistry occurred at the site.…”

Section: Resultsmentioning

confidence: 99%

“…The magnitude of the observed decreases in TCE/ c DCE ratios, however, appears to be related in part to depth to ground water. By the end of the fifth growing season (2000), Eberts et al (2003) observed the lowest TCE/ c DCE ratios where depth to water was <3 m. They also observed that water from wells with the lowest TCE/ c DCE ratios (511, 514, 515) had the highest DOC concentrations, 1.6 to 1.8 mg/L (with a hydrophilic acids DOC fraction—DOC fraction that is labile or readily consumable by microorganisms—≥0.4 mg/L), and the lowest D.O. concentrations, 0.93 to 1.7 mg/L.…”

Section: Resultsmentioning

confidence: 99%

Long‐term changes in ground water chemistry at a phytoremediation demonstration site

et al. 2005

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A field-scale demonstration project was conducted to evaluate the capability of eastern cottonwood trees (Populus deltoides) to attenuate trichloroethene (TCE) contamination of ground water. By the middle of the sixth growing season, trees planted where depth to water was <3 m delivered enough dissolved organic carbon to the underlying aquifer to lower dissolved oxygen concentrations, to create iron-reducing conditions along the plume centerline and sulfate-reducing or methanogenic conditions in localized areas, and to initiate in situ reductive dechlorination of TCE. Apparent biodegradation rate constants for TCE along the centerline of the plume beneath the phytoremediation system increased from 0.0002/d to 0.02/d during the first six growing seasons. The corresponding increase in natural attenuation capacity of the aquifer along the plume centerline, from 0.0004/m to 0.024/m, is associated with a potential decrease in plume-stabilization distance from 9680 to 160 m. Demonstration results provide insight into the amount of vegetation and time that may be needed to achieve cleanup objectives at the field scale.

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“…At phytoremediation sites, they are necessary for evaluating diurnal fluctuations (Landmeyer, 2001). Eberts et al (2003) demonstrated the use of continuous groundwater-level probe data from a phytoremediation plantation to estimate transpiration rates. Hirsh et al (2003) instrumented a phytoremedial plantation with dozens of probes, and they observed seasonal diurnal effects, including daily declines of 4.6 cm (1.8 in) within the plantation.They also discovered a seasonal vertical gradient reversal attributed to water usage of the site's poplars.…”

Section: Introductionmentioning

confidence: 99%

Continuous water-level monitoring in the assessment of groundwater remediation and refinement of a conceptual site model

Quinn

Johnson

2005

Remediation

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Water-level data collection is a fundamental component of groundwater investigations and remediation. While the locations and depths of monitored wells are important, the frequency of data collection may have a large impact on conclusions made about site hydrogeology. Data-logging water-level probes may be programmed to record water levels at frequent intervals, providing site decision makers with abundant, detailed information on the response of an aquifer to both anticipated and unforeseen stresses. In this study, a network of movable probes has provided several years of hourly water-level data. The understanding of the site's phytoremediation system has been enhanced by the continuous data, but subsequent insights into an unexpected situation regarding the site's infrastructure have been the most valuable result of the monitoring program.

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Multiple‐Process Assessment for a Chlorinated‐Solvent Plume

Cited by 13 publications

References 0 publications

Ground Water Chlorinated Ethenes in Tree Trunks: Case Studies, Influence of Recharge, and Potential Degradation Mechanism

Ground Water Chlorinated Ethenes in Tree Trunks: Case Studies, Influence of Recharge, and Potential Degradation Mechanism

Long‐term changes in ground water chemistry at a phytoremediation demonstration site

Continuous water-level monitoring in the assessment of groundwater remediation and refinement of a conceptual site model

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