Transport and fate of chlorinated hydrocarbons in the vadose zone — a literature review with discussions on regulatory implications

Env., Samuel C. T. Yu D.

doi:10.1080/15320389509383480

Cited by 6 publications

(4 citation statements)

References 108 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Th e absence of substantial concentrations of VOCs in the groundwater indicates that transport of VOCs is dominated by unsaturated-zone processes. Similar dynamics have been modeled and measured at other VOC-contaminated sites (Mendoza and Mc Alary, 1990;Yu, 1994). Exchanges have also been documented where VOCs in groundwater were transported up into the overlying unsaturated zone (e.g., McCarthy and Johnson, 1993).…”

Section: Fig 4 Unsaturated-zone Vapor Concentrations Of Total Volatsupporting

confidence: 69%

Volatile Organic Compounds in the Unsaturated Zone from Radioactive Wastes

et al. 2012

View full text Add to dashboard Cite

Volatile organic compounds (VOCs) are often comingled with low-level radioactive wastes (LLRW), but little is known about subsurface VOC emanations from LLRW landfills. The current study systematically quantified VOCs associated with LLRW over an 11-yr period at the USGS Amargosa Desert Research Site (ADRS) in southwestern Nevada. Unsaturated-zone gas samples of VOCs were collected by adsorption on resin cartridges and analyzed by thermal desorption and GC/MS. Sixty of 87 VOC method analytes were detected in the 110-m-thick unsaturated zone surrounding a LLRW disposal facility. Chlorofluorocarbons (CFCs) were detected in 100% of samples collected. Chlorofluorocarbons are powerful greenhouse gases, deplete stratospheric ozone, and are likely released from LLRW facilities worldwide. Soil-gas samples collected from a depth of 24 m and a horizontal distance 100 m south of the nearest waste-disposal trench contained >60,000 ppbv total VOCs, including >37,000 ppbv CFCs. Extensive sampling in the shallow unsaturated zone (0-2 m deep) identified areas where total VOC concentrations exceeded 5000 ppbv at the 1.5-m depth. Volatile organic compound concentrations exceeded background levels up to 300 m from the facility. Maximum vertical diffusive fluxes of total VOCs were estimated to be 1 g m yr. Volatile organic compound distributions were similar but not identical to those previously determined for tritium and elemental mercury. To our knowledge, this study is the first to characterize the unsaturated zone distribution of VOCs emanating from a LLRW landfill. Our results may help explain anomalous transport of radionuclides at the ADRS and elsewhere.

show abstract

Section: Fig 4 Unsaturated-zone Vapor Concentrations Of Total Volatsupporting

confidence: 69%

Volatile Organic Compounds in the Unsaturated Zone from Radioactive Wastes

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Remediation of such contaminated sites is particularly challenging when chlorinated solvents are present in the form of residual droplets or pools in the subsurface beneath existing aboveground infrastructure. Because the dissolution and desorption/diffusion rates of chlorinated solvents are very slow, they represent a long‐term source of soil and groundwater contamination (Poulsen and Kueper, 1992; Stroo et al, 2003; Yu, 1995). When the excavation of contaminated soil is too costly or impossible (due to, for example, the presence of aboveground infrastructure), a common alternative used for soils affected by volatile and semivolatile organic chemicals (such as PCE and TCE) is soil vapor extraction (Nobre and Nobre, 2004).…”

mentioning

confidence: 99%

Material Flow Analysis: An Effectiveness Assessment Tool for In Situ Thermal Remediation

Laumann

Micić

Fellner

et al. 2013

Vadose Zone Journal

View full text Add to dashboard Cite

In situ thermal desorption (ISTD) is a remediation technique that increases the effectiveness of soil vapor extraction through the simultaneous application of heat and vacuum. In this study, ISTD was applied to remove a chlorinated solvent source from unsaturated soil beneath an existing aboveground infrastructure. A material flow analysis (MFA) was applied for the first time to assess the effectiveness of ISTD in the vadose zone and to reveal the total emission of chlorinated solvents into the environment before and during remediation. The principle of matter conservation used in MFA enabled the quantification of chlorinated solvent flows in all matrices affected: soil, groundwater, and soil vapor. The MFA results revealed that the mass removed by ISTD was similar to the mean chlorinated solvent mass estimated to have been present in the soil before remediation, indicating high effectiveness in contaminant removal. The remediation target value in soil vapor was achieved after 9 mo of remediation, demonstrating the time efficiency of ISTD for this particular site. The MFA additionally provided an overview of the processes and contaminant transformations occurring in the soil, water, and air compartments during the course of remediation.

show abstract

“…When released to the soil, gasoline is transported in vapour and liquid phases. However, the vapour phase spreads much more efficiently than the liquid phase and can migrate towards groundwater when the liquid phase transport has stopped [26]. Consequently, the vapour phase has been extensively used in the investigation of the transport of volatile hydrocarbons in the vadose zone [4, 6-10, 12, 13, 15, 17, 24].…”

Section: Introductionmentioning

confidence: 99%

Vapour phase transport of ethanol- and butanol-blended gasoline compounds in the vadose zone: a lysimeter experiment

Ugwoha

2014

Int J Energy Environ Eng

View full text Add to dashboard Cite

Lysimeter experiments were conducted to compare the vapour phase transport of 20 % ethanol-and butanol-blended gasoline (E20 and B20) compounds in soils using the unblended gasoline (UG) compounds as the standard. Sand containing approximately 0 and 5 % organic matter (0 %f om and 5 %f om ) was used to simulate the vadose zone. The 5 %f om soil promoted higher vapour phase transport of compounds than the 0 %f om soil due to its higher porosity, hence, was used to compare the transport to the groundwater zone of the different gasoline blends. The addition of 20 % alcohol by volume to gasoline reduced the retentive capability of the soil for gasoline compound vapours and thus resulted in greater downward transport and higher accumulation of gasoline compounds in the groundwater zone. The transport of gasoline compounds from the vadose zone to the groundwater zone was found to be in the order of E20 [ B20 [ UG, indicating that the risk of groundwater contamination with gasoline compounds after a spill or leak is more likely to be greater for ethanolblended gasoline compared with butanol-blended gasoline.

show abstract

Transport and fate of chlorinated hydrocarbons in the vadose zone — a literature review with discussions on regulatory implications

Cited by 6 publications

References 108 publications

Volatile Organic Compounds in the Unsaturated Zone from Radioactive Wastes

Volatile Organic Compounds in the Unsaturated Zone from Radioactive Wastes

Material Flow Analysis: An Effectiveness Assessment Tool for In Situ Thermal Remediation

Vapour phase transport of ethanol- and butanol-blended gasoline compounds in the vadose zone: a lysimeter experiment

Contact Info

Product

Resources

About