Source Identification and Age Dating of Chlorinated Solvents

Morrison, Robert; Murphy, Brian L.

doi:10.1016/b978-0-12-404696-2.00009-6

Cited by 6 publications

(5 citation statements)

References 111 publications

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“…Additionally, some fraction may have originated from TCE particularly because TCA and its daughter products simply do not account for all dioxane detections in wells with TCE (Exhibit 8), although fate and transport differences as well as the sequential use of TCE and TCA complicate the interpretation of dioxane occurrence (Adamson et al, 2014). Further evidence is provided by the U.S. patent literature, which suggests some TCE formulations may have contained dioxane (Morrison & Murphy, 2015) and previous analyses of these data demonstrating categorical and quantitative statistical associations between TCE and dioxane (Anderson et al, 2012). Regardless, TCE and/or TCA account for essentially all dioxane contamination at industrial sites impacted by chlorinated solvents as shown in these data (Exhibit 8; Anderson et al,2012) and elsewhere (Adamson et al, 2014).…”

Section: Us Dod Perspective Of Dioxane Issuesmentioning

confidence: 99%

Practical Perspectives of 1,4‐Dioxane Investigation and Remediation

Chiang

Anderson

Wilken

et al. 2016

Remediation Journal

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1,4‐Dioxane (dioxane) is a contaminant of emerging concern that is classified by the U.S. Environmental Protection Agency as a likely human carcinogen. Dioxane has been used as a minor or major ingredient in many applications, and is also generated as an unwanted by‐product of industrial processes associated with the manufacturing of polyethylene, nonionic surfactants, and many consumer products (cosmetics, laundry detergents, shampoos, etc.). Dioxane is also a known stabilizer of chlorinated solvents, particularly 1,1,1‐trichloroethane, and has been commonly found comingled with chlorinated solvent plumes. Dioxane plumes at chlorinated solvent sites can complicate site closure strategies, which to date have not typically focused on dioxane. Aggressive treatment technologies have greatly advanced and are clearly capable of achieving lower parts per billion cleanup criteria using ex situ advanced oxidation processes and sorption media. In situ chemical oxidation has also been demonstrated to effectively remediate dioxane and chlorinated solvents. Other in situ remedies, such as enhanced bioremediation, phytoremediation, and monitored natural attenuation, have been studied; however, their ability to achieve cleanup levels is still somewhat questionable and is limited by co‐occurring contaminants. This article summarizes and provides practical perspectives on dioxane analysis, plume stability relative to other contaminants, and the development of investigation tools and treatment technologies.

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Section: Us Dod Perspective Of Dioxane Issuesmentioning

confidence: 99%

Practical Perspectives of 1,4‐Dioxane Investigation and Remediation

Chiang

Anderson

Wilken

et al. 2016

Remediation Journal

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“…The development of effective strategies for managing sites where groundwater is impacted by the emerging contaminant 1,4-dioxane (dioxane) represents a significant challenge. − Dioxane is frequently present at sites where chlorinated solvents are detected ,, primarily because of its widespread use as a stabilizer in 1,1,1-trichloroethane (TCA) formulations . However, dioxane was not exclusively used to stabilize TCA (according to the U.S. Patent Literature) and may have been used to stabilize some formulations of other chlorinated solvents . Furthermore, trichloroethene (TCE) was used as a solvent at many of these same industrial sites during the periods both before and after TCA.…”

Section: Introductionmentioning

confidence: 99%

“…1 However, dioxane was not exclusively used to stabilize TCA (according to the U.S. Patent Literature) and may have been used to stabilize some formulations of other chlorinated solvents. 5 Furthermore, trichloroethene (TCE) was used as a solvent at many of these same industrial sites during the periods both before and after TCA. The presence of multiple contaminants with widely varying chemical characteristics adds to the complexity of the remedial decision-making process.…”

Section: ■ Introductionmentioning

confidence: 99%

Evidence of 1,4-Dioxane Attenuation at Groundwater Sites Contaminated with Chlorinated Solvents and 1,4-Dioxane

Adamson

Anderson

Mahendra

et al. 2015

Environ. Sci. Technol.

103

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There is a critical need to develop appropriate management strategies for 1,4-dioxane (dioxane) due to its widespread occurrence and perceived recalcitrance at groundwater sites where chlorinated solvents are present. A comprehensive evaluation of California state (GeoTracker) and Air Force monitoring records was used to provide significant evidence of dioxane attenuation at field sites. Temporal changes in the site-wide maximum concentrations were used to estimate source attenuation rates at the GeoTracker sites (median length of monitoring period = 6.8 years). While attenuation could not be established at all sites, statistically significant positive attenuation rates were confirmed at 22 sites. At sites where dioxane and chlorinated solvents were present, the median value of all statistically significant dioxane source attenuation rates (equivalent half-life = 31 months; n = 34) was lower than 1,1,1-trichloroethane (TCA) but similar to 1,1-dichloroethene (1,1-DCE) and trichloroethene (TCE). Dioxane attenuation rates were positively correlated with rates for 1,1-DCE and TCE but not TCA. At this set of sites, there was little evidence that chlorinated solvent remedial efforts (e.g., chemical oxidation, enhanced bioremediation) impacted dioxane attenuation. Attenuation rates based on well-specific records from the Air Force data set confirmed significant dioxane attenuation (131 out of 441 wells) at a similar frequency and extent (median equivalent half-life = 48 months) as observed at the California sites. Linear discriminant analysis established a positive correlation between dioxane attenuation and increasing concentrations of dissolved oxygen, while the same analysis found a negative correlation with metals and CVOC concentrations. The magnitude and prevalence of dioxane attenuation documented here suggest that natural attenuation may be used to manage some but not necessarily all dioxane-impacted sites.

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“…Historically, TCE was first produced by chlorination of acetylene to 1,1,2,2-tetrachloroethane, followed by dehydrochlorination to TCE. The acetylene process was replaced by ethene chlorination to 1,2-dichloroethane, followed by a chlorination/oxychlorination to TCE . It is possible that the acetylene process was associated with less 2 H enrichment, owing to fewer steps with hydrogen kinetic isotope effects along the reaction chain, but this was never confirmed by analysis of a well-provenanced product from the acetylene process.…”

Section: Results and Discussionmentioning

confidence: 99%

Hydrogen Isotope Exchange between Trichloroethene and Water under Mild Environmental Conditions─Implications for the Use of Hydrogen CSIA in Contaminated Site Assessment

Kuder

Ojeda

2023

ACS EST Water

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Trichloroethylene (TCE) is a key legacy environmental contaminant and a major target for contaminant remediation projects. Hydrogen compound-specific isotope analysis (CSIA) of halocarbons is a relatively recent technique, predominantly used as a line of evidence for apportionment of TCE sources. To date, no published data addressed the potential for hydrogen exchange between TCE and hydroxide in a water solution under typical groundwater pH conditions. In this study, we determined the pH-and temperature-dependent rates of exchange in controlled experiments to constrain the scope of applications of hydrogen CSIA at field sites contaminated by TCE. Relatively high rates of the exchange were associated with aboveneutral pH typical of carbonate aquifers (half-lives of years to decades) and slower, but not negligible, rates were associated with sub-neutral pH. Hydrogen exchange alters the hydrogen isotope composition of TCE in solution, masking initial source signatures or degradation signatures over environmentally relevant time scales. In effect, the TCE−water exchange restricts the classical applications of hydrogen CSIA data to a subset of distinctly acidic environments. On the other hand, as the rates of the exchange can be predicted for specific combinations of pH and temperature, the process could be potentially utilized in age-dating of TCE contamination.

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Source Identification and Age Dating of Chlorinated Solvents

Cited by 6 publications

References 111 publications

Practical Perspectives of 1,4‐Dioxane Investigation and Remediation

Practical Perspectives of 1,4‐Dioxane Investigation and Remediation

Evidence of 1,4-Dioxane Attenuation at Groundwater Sites Contaminated with Chlorinated Solvents and 1,4-Dioxane

Hydrogen Isotope Exchange between Trichloroethene and Water under Mild Environmental Conditions─Implications for the Use of Hydrogen CSIA in Contaminated Site Assessment

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