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Light Non-Aqueous Phase Liquids (LNAPLs)


LNAPL (Light Nonaqueous Phase Liquid) - "An LNAPL is one of a group of organic substances that are relatively insoluble in water and are less dense than water. LNAPLs, such as oil, tend to spread across the surface of the water table and form a layer on top of the water table." - U.S. Environmental Protection Agency, 2010

LNAPL – “An acronym for less-dense-than-water nonaqueous-phase liquid. LNAPLs do not mix well with water and are less dense than water. Gasoline and fuel oil are common LNAPLs.” – National Research Council, 1994

LNAPL – “Petroleum chemicals (mainly benzene, toluene, xylene, and benzene derivatives) categorized as light nonaqueous-phase liquids (LNAPLs) tend to form pools and spread laterally (Martel and Ayotte, 1989) because of their low densities.” – Lesage and Jackson, 1992


A cross sectional view of a hypothetical LNAPL spill
unsaturated zone graphic

Figure has been adapted from Delin and others, 1998, USGS Fact Sheet FS-084-98.


Related Definitions

Non-Aqueous Phase Liquids (NAPLs)

Dense Non-Aqueous Phase Liquids (DNAPLs)

USGS Toxics Program Investigations on LNAPLs

Related Science Feature Articles

Other Information on LNAPLs


Lesage, S., and Jackson, R.E., 1992, Groundwater contamination and analysis at hazardous waste sites: Marcel Dekker, Inc., 552 p.

Martel, R., and Ayotte, P., 1989, Etat de la situation sur la contamination de la nappe souterraine dans la region de Ville Mercier: Ministere de l'Environment du Quebec.

National Research Council, 1994, Alternatives for ground water cleanup: Washington, D.C., National Academies Press, 315 p.

U.S. Environmental Protection Agency, 2010, Waste and cleanup risk assessment glossary: U.S. Environmental Protection Agency, access date July, 27, 2010.



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