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Grabert, Vicki Kretsinger; Kaback, D.S.; Parker, Beth L.; Chapman, S.; Cherry, John A.; Chapelle, Francis H.; Singletary, Michael A.; Einarson, Murray; Mackay, Doug; Bennett, P.J.

doi:10.1111/j.1745-6584.2010.00755.x

Cited by 9 publications

(2 citation statements)

References 26 publications

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“…Therefore, the conclusions presented in this paper concerning the TCE in the Smallfield well apply only to the non-pumping condition. During the pre-1994 pumping period, it is likely that TCE from each of the various industrial properties formed plumes that were captured by the Smallfield well and that these source zones and plumes had much of their mass diffused into the porous but low permeability dolostone matrix blocks between fractures, as described conceptually by Parker et al (1997) and Parker et al (2010) with a strong degree of plume attenuation and plume front retardation relative to rapid groundwater velocity in the fracture network. This study shows that there are closer industrial TCE sources in the groundwater system that are now dominating the Smallfield well contamination and due to their relatively close proximity to the well, it is likely that these sources were also the major contributors to the well as the pre-1994 capture zone would have encompassed them.…”

Section: Discussionmentioning

confidence: 99%

Fingerprinting TCE in a Bedrock Aquifer Using Compound‐Specific Isotope Analysis

et al. 2012

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A dual isotope approach based on compound-specific isotope analysis (CSIA) of carbon (C) and chlorine (Cl) was used to identify sources of persistent trichloroethylene (TCE) that caused the shut-down in 1994 of a municipal well in an extensive fractured dolostone aquifer beneath Guelph, Ontario. Several nearby industrial properties have known subsurface TCE contamination; however, only one has created a comprehensive monitoring network in the bedrock. The impacted municipal well and many monitoring wells were sampled for volatile organic compounds (VOCs), inorganic parameters, and CSIA. A wide range in isotope values was observed at the study site. The TCE varies between -35.6‰ and -21.8‰ and from 1.6‰ to 3.2‰ for δ(13) C and δ(37) Cl, respectively. In case of cis-1,2-dichloroethene, the isotope values range between -36.3‰ and -18.9‰ and from 2.4‰ to 4.7‰ for δ(13) C and δ(37) Cl, respectively. The dual isotope approach represented by a plot of δ(13) C vs. δ(37) Cl shows the municipal well samples grouped in a domain clearly separate from all other samples from the property with the comprehensive well network. The CSIA results collected under non-pumping and short-term pumping conditions thus indicate that this particular property, which has been studied intensively for several years, is not a substantial contributor of the TCE presently in the municipal well under non-pumping conditions. This case study demonstrates that CSIA signatures would have been useful much earlier in the quest to examine sources of the TCE in the municipal well if bedrock monitoring wells had been located at several depths beneath each of the potential TCE-contributing properties. Moreover, the CSIA results show that microbial reductive dechlorination of TCE occurs in some parts of the bedrock aquifer. At this site, the use of CSIA for C and Cl in combination with analyses of VOC and redox parameters proved to be important due to the complexity introduced by biodegradation in the complex fractured rock aquifer. It is highly recommended to revisit the study when the municipal well is back into full operation.

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Section: Discussionmentioning

confidence: 99%

Fingerprinting TCE in a Bedrock Aquifer Using Compound‐Specific Isotope Analysis

et al. 2012

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“…The characterization and modeling of transport processes in fractured environment is particularly challenging due to the extreme heterogeneity of flow rates and transport time scales (Blessent et al, 2014;Kang et al, 2015;Tsang, 1995;Weatherill et al, 2008). Preferential flow in fracture networks promotes fast transfers, while diffusion from the fractures into the rock matrix can lead to very long residence times (Becker & Shapiro, 2000Haggerty et al, 2000;Hyman et al, 2019;Kang et al, 2015;Parker et al, 2010).…”

Section: Motivationmentioning

confidence: 99%

Continuous Dissolved Gas Tracing of Fracture‐Matrix Exchanges

Hoffmann

Goderniaux

Jamin

et al. 2020

Geophysical Research Letters

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Transport in fractured media plays an important role in a range of processes, from rock weathering and microbial processes to contaminant transport, and energy extraction and storage. Diffusive transfer between the fracture fluid and the rock matrix is often a key element in these applications. But the multiscale heterogeneity of fractures renders the field assessment of these processes extremely challenging. This study explores the use of dissolved gases as tracers of fracture‐matrix interactions, which can be measured continuously and highly accurately using mobile mass spectrometers. Since their diffusion coefficients vary significantly, multiple gases are used to probe different scales of fracture‐matrix exchanges. Tracer tests with helium, xenon, and argon were performed in a fractured chalk aquifer, and resulting tracer breakthrough curves are modeled. Results show that continuous dissolved gas tracing with multiple tracers provides key constrains on fracture‐matrix interactions and reveal unexpected scale effects in fracture‐matrix exchange rates.

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