The use of SF[sub 6] to detect residual DNAPL below the water table

Conference · Fri Oct 01 00:00:00 EDT 1993 · Journal of Environmental Health; (United States)

OSTI ID:5898166

Wilson, R D; Mackay, D M ^[1]

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1. Univ. of Waterloo, Ontario (Canada). Waterloo Centre for Groundwater Research

When dense chlorinated solvents are spilled on or near the surface, downward migration results in the formation of residual zones of discontinuous stringers and blobs of pure nonaqueous phase. These low solubility compounds represent extremely longterm sources of organic contaminants, and must be located in order to effect remediation. Location of such zones can be extremely difficult, or even impossible, if the exact location of a spill is unknown, or if DNAPL movement is complicated by even subtle aquifer heterogeneities. A simple method that can detect the presence and possibly quantify the amount of such compounds is being studied that could prove valuable in the remediation of dense chlorinated solvent contamination problems. Sulphur Hexafluoride (SF[sub 6]) has been shown to behave as a conservative, nonreactive tracer in a wide variety of saturated sandy media, but has properties that may make it useful in detecting the presence and amount of residual nonaqueous phases. SF[sub 6] is a neutral, nontoxic, volatile gas that can be detected easily by gas chromatography using an electron capture detector. Lab studies show that SF[sub 6] will not sorb to aquifer material with organic carbon content as high as 2% by weight; however, measured octanol-water partitioning values (log K[sub ow] = 1.14) suggest that SF[sub 6] will partition to PCE and TCE as well. Because most organic phases are typically less polar than water, SF[sub 6] may be capable of detecting the presence of a wide range of volatile organic compounds.

• OSTI ID: 5898166
• Report Number(s): CONF-9310166-; CODEN: JEVHAH
• Journal Information: Journal of Environmental Health; (United States), Vol. 56:3; Conference: Association of Ground Water Scientists and Engineers (AGWSE) educational seminar on chlorinated volatile organic compounds in ground water, Kansas City, MO (United States), 17-20 Oct 1993; ISSN 0022-0892
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CHLORINATED ALIPHATIC HYDROCARBONS
ENVIRONMENTAL TRANSPORT
GROUND WATER
CONTAMINATION
SULFUR FLUORIDES
PERFORMANCE
CHEMICAL SPILLS
TRACER TECHNIQUES
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
MASS TRANSFER
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXYGEN COMPOUNDS
SULFUR COMPOUNDS
WATER
540220* - Environment
Terrestrial- Chemicals Monitoring & Transport- (1990-)