Vadose zone nonaqueous-phase liquid characterization using partitioning gas tracers
- Univ. of Texas, Austin, TX (United States). Dept. of Petroleum and Geosystems Engineering
- INTERA, Inc., Austin, TX (United States)
Researchers of various disciplines associated with environmental cleanup are beginning to investigate the use of partitioning tracers to determine and characterize contaminated sites. Characterizing the vadose, or unsaturated zone, as well as the saturated zone is imperative because there are areas in the western US with large vadose zones that are contaminated by nonaqueous-phase liquids (NAPLs). This paper presents laboratory experiments conducted to determine the partition coefficients between air and NAPL for several gas tracers. Once the tracers` partition coefficients have been estimated, they may be used to estimate NAPL volumes in situ. The experiments entailed the introduction of trichloroethylene (TCE) into a column packed with Ottawa sand and containing a residual amount of water. With a known amount of TCE in the column, partitioning gas tracers were injected and their breakthrough monitored. Using the method of moments, the partition coefficients of the tracers were estimated. The gas tracers used in this experiment included argon as a nonpartitioning tracer and several perfluorocarbons as partitioning tracers. The experimental results demonstrate that partitioning gas tracers and, in particular, perfluorocarbons, may be used to estimate residual NAPL saturations in the vadose zone.
- Sponsoring Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- OSTI ID:
- 492248
- Report Number(s):
- CONF-950483--; ISBN 1-57477-006-3
- Country of Publication:
- United States
- Language:
- English
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