Experimental Investigations of the Entrapment and Persistence of Organic Liquid Contaminants in the Subsurface Environment

Organic liquids are common polluters of the subsurface environment. Once released, these nonaqueous phase liquids (NAPLs) tend to become entrapped within soils and geologic formations where they may serve as long-term contaminant reservoirs. The interphase mass transfer from such entrapped residuals...

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Bibliographic Details
Published inEnvironmental health perspectives Vol. 106; no. suppl 4; pp. 1083 - 1095
Main Authors Abriola, Linda M., Bradford, Scott A.
Format Journal Article
LanguageEnglish
Published United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01.08.1998
Subjects
Coefficients
Environmental Monitoring
Geologic Sediments - chemistry
Groundwater
Mass transfer
Nonaqueous phase liquids
Organic Chemicals - pharmacokinetics
Porosity
Porous materials
Risk Reduction
Soil Pollutants - pharmacokinetics
Soil pollution
Soil water
Styrenes
Vaporizing
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Summary:Organic liquids are common polluters of the subsurface environment. Once released, these nonaqueous phase liquids (NAPLs) tend to become entrapped within soils and geologic formations where they may serve as long-term contaminant reservoirs. The interphase mass transfer from such entrapped residuals will ultimately control environmental exposure levels as well as the persistence and/or remedial recovery of these contaminants in the subsurface. This paper summarizes National Institute of Environmental Health Sciences-sponsored research designed to investigate and quantify NAPL entrapment and interphase mass transfer in natural porous media. Results of soil column and batch experiments are presented that highlight research findings over the past several years. These experiments explore dissolution and volatilization of hydrocarbons and chlorinated solvents in sandy porous media. Initial concentration levels and long-term recovery rates are shown to depend on fluid flow rate, soil structure, NAPL composition, and soil wetting characteristics. These observations are explained in the context of conceptual models that describe entrapped NAPL morphology and boundary layer transport. The implications of these laboratory findings on the subsurface persistence and recovery of entrapped NAPLs are discussed.
ISSN:0091-6765
1552-9924
DOI:10.1289/ehp.98106s41083