Partitioning tracer method for the in situ measurement of DNAPL saturation: Influence of heterogeneity and sampling method

Nicole T. Nelson, Mart Oostrom, Tom W. Wietsma, Mark L Brusseau

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The purpose of this work was to examine the effect of porous-media heterogeneity, nonuniform distribution of dense nonaqueous phase liquid (DNAPL), and sampling method on the performance of the partitioning tracer method for measuring DNAPL saturation in water-saturated subsurface systems. Experiments were conducted in an intermediate-scale flow cell that contained two discrete zones of trichloroethene (TCE) at residual saturation. One zone (zone 2) consisted of ~10% saturation formed in the same sand as used for the flow-cell matrix. The other zone (zone 1) consisted of ~10% saturation in a finer sand emplaced within the coarser matrix. Aqueous samples were collected using depth-specific sampling, using vertically integrated sampling, and at the extraction well. A dual-energy γ radiation system was used to measure TCE saturation before and after the tracer experiment, allowing the measurements obtained from the tracer experiment to be compared to a previously tested method. The saturations estimated using the data collected at point-sampling ports located downgradient of zones 1 and 2 were approximately 7% and 50% of the true values, respectively. The saturations estimated using the data obtained from the vertically integrated ports were 0% and 6% of the true values, respectively. Finally, the saturation estimated using the extraction-well data was 30% of the cell-wide averaged value. These results indicate that the presence of porous-media heterogeneity and a variable distribution of DNAPL saturation can lead to reduced accuracy of the partitioning tracer test. The reduced performance can be improved, in part, by using depth-specific sampling.

Original languageEnglish (US)
Pages (from-to)4046-4053
Number of pages8
JournalEnvironmental Science and Technology
Volume33
Issue number22
DOIs
StatePublished - 1999
Externally publishedYes

Fingerprint

nonaqueous phase liquid
in situ measurement
partitioning
tracer
saturation
Sampling
sampling
Liquids
Trichloroethylene
Porous materials
Sand
trichloroethylene
Experiments
porous medium
method
matrix
sand
Radiation
experiment
Water

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry
  • Environmental Engineering

Cite this

Partitioning tracer method for the in situ measurement of DNAPL saturation : Influence of heterogeneity and sampling method. / Nelson, Nicole T.; Oostrom, Mart; Wietsma, Tom W.; Brusseau, Mark L.

In: Environmental Science and Technology, Vol. 33, No. 22, 1999, p. 4046-4053.

Research output: Contribution to journalArticle

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