Intercalation of trichloroethene by sediment-associated clay minerals

Matthieu, D. E.; Brusseau, Mark L.; Johnson, Gerald R.; Artiola, J. L.; Bowden, Mark E.; Curry, Jane

doi:10.1016/j.chemosphere.2012.07.061

Cited by 9 publications

(8 citation statements)

References 12 publications

(14 reference statements)

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“…The subsurface consists of clay and silty clay units with localized and discontinuous intervals/lenses of silt, sand, and gravel. The clay is typically highly plastic, and is comprised primarily of muscovite, illite, and montmorillonite (Matthieu et al, 2012). A prominent feature is a sand and/or gravel unit, termed the gravel sub-unit, of significant areal extent present between approximately 34 and 38 m below land surface (bls).…”

Section: Methodsmentioning

confidence: 99%

Characterizing long-term contaminant mass discharge and the relationship between reductions in discharge and reductions in mass for DNAPL source areas

Brusseau

Matthieu

Carroll

et al. 2013

Journal of Contaminant Hydrology

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The objective of this study was to characterize the temporal behavior of contaminant mass discharge, and the relationship between reductions in contaminant mass discharge and reductions in contaminant mass, for a very heterogeneous, highly contaminated source-zone field site. Trichloroethene is the primary contaminant of concern, and several lines of evidence indicate the presence of organic liquid in the subsurface. The site is undergoing groundwater extraction for source control, and contaminant mass discharge has been monitored since system startup. The results show a significant reduction in contaminant mass discharge with time, decreasing from approximately 1 to 0.15 kg/d. Two methods were used to estimate the mass of contaminant present in the source area at the initiation of the remediation project. One was based on a comparison of two sets of core data, collected 3.5 years apart, which suggests that a significant (~80%) reduction in aggregate sediment-phase TCE concentrations occurred between sampling events. The second method was based on fitting the temporal contaminant mass discharge data with a simple exponential source-depletion function. Relatively similar estimates, 784 and 993 kg, respectively, were obtained with the two methods. These data were used to characterize the relationship between reductions in contaminant mass discharge (CMDR) and reductions in contaminant mass (MR). The observed curvilinear relationship exhibits a reduction in contaminant mass discharge essentially immediately upon initiation of mass reduction. This behavior is consistent with a system wherein significant quantities of mass are present in hydraulically poorly accessible domains for which mass removal is influenced by rate-limited mass transfer. The results obtained from the present study are compared to those obtained from other field studies to evaluate the impact of system properties and conditions on mass-discharge and mass-removal behavior. The results indicated that factors such as domain scale, hydraulic-gradient status (induced or natural), and flushing-solution composition had insignificant impact on the CMDR-MR profiles and thus on underlying mass-removal behavior. Conversely, source-zone age, through its impact on contaminant distribution and accessibility, was implicated as a critical factor influencing the nature of the CMDR-MR relationship.

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Section: Methodsmentioning

confidence: 99%

Characterizing long-term contaminant mass discharge and the relationship between reductions in discharge and reductions in mass for DNAPL source areas

Brusseau

Matthieu

Carroll

et al. 2013

Journal of Contaminant Hydrology

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“…The low‐permeability sediments comprise a high percentage of clay minerals, including smectitic clays (Matthieu et al ). The results of studies conducted with sediments from the site indicate that TCE can be intercalated within the interlayer spaces of clay minerals associated with the site sediments (Matthieu et al ). This intercalation may contribute to recalcitrance and plume persistence by constraining desorption.…”

Section: Resultsmentioning

confidence: 99%

“…The subsurface consists of clay and silty clay units with localized and discontinuous intervals/lenses of silt, sand, and gravel. The clay is in some cases highly plastic and it comprised primarily muscovite, illite, and montmorillonite (Matthieu et al ). A prominent feature is a sand and/or gravel unit of significant areal extent present between approximately 34‐ and 37‐m below land surface (bls).…”

Section: Methodsmentioning

confidence: 99%

Persistence of a Groundwater Contaminant Plume after Hydraulic Source Containment at a Chlorinated‐Solvent Contaminated Site

Matthieu¹,

Brusseau²,

Guo³

et al. 2014

Groundwater Monitoring Rem

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The objective of this study was to characterize the behavior of a groundwater contaminant (trichloroethene) plume after implementation of a source-containment operation at a site in Arizona. The plume resides in a quasi three-layer system comprising a sand/gravel unit bounded on the top and bottom by relatively thick silty clayey layers. The system was monitored for 60 months beginning at start-up in 2007 to measure the change in contaminant concentrations within the plume, the change in plume area, the mass of contaminant removed, and the integrated contaminant mass discharge. Concentrations of trichloroethene in groundwater pumped from the plume extraction wells have declined significantly over the course of operation, as have concentrations for groundwater sampled from 40 monitoring wells located within the plume. The total contaminant mass discharge associated with operation of the plume extraction wells peaked at 0.23 kg/d, decreased significantly within one year, and thereafter began an asymptotic decline to a current value of approximately 0.03 kg/d. Despite an 87% reduction in contaminant mass and a comparable 87% reduction in contaminant mass discharge for the plume, the spatial area encompassed by the plume has decreased by only approximately 50%. This is much less than would be anticipated based on ideal flushing and mass-removal behavior. Simulations produced with a simplified 3-D numerical model matched reasonably well to the measured data. The results of the study suggest that permeability heterogeneity, back diffusion, hydraulic factors associated with the specific well field system, and residual discharge from the source zone are all contributing to the observed persistence of the plume, as well as the asymptotic behavior currently observed for mass removal and for the reduction in contaminant mass discharge.

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“…The subsurface consists of clay and silty clay units with localized intervals/lenses of silt, sand, and gravel (see Figure 2). The clay is typically highly plastic, and is comprised primarily of muscovite, illite, and montmorillonite (Matthieu et al, 2013). The potentiometric surface for the shallow groundwater zone is approximately 28–29 m below land surface (bls) in the vicinity of the source area.…”

Section: Methodsmentioning

confidence: 99%

Using vapor phase tomography to measure the spatial distribution of vapor concentrations and flux for vadose-zone VOC sources

Mainhagu

Morrison

Brusseau

2015

Journal of Contaminant Hydrology

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A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were combined with the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site.

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Intercalation of trichloroethene by sediment-associated clay minerals

Cited by 9 publications

References 12 publications

Characterizing long-term contaminant mass discharge and the relationship between reductions in discharge and reductions in mass for DNAPL source areas

Characterizing long-term contaminant mass discharge and the relationship between reductions in discharge and reductions in mass for DNAPL source areas

Persistence of a Groundwater Contaminant Plume after Hydraulic Source Containment at a Chlorinated‐Solvent Contaminated Site

Using vapor phase tomography to measure the spatial distribution of vapor concentrations and flux for vadose-zone VOC sources

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