Measurement of effective air diffusion coefficients for trichloroethene in undisturbed soil cores

Shannon L. Bartelt-Hunt, James A. Smith

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

In this study, we measure effective diffusion coefficients for trichloroethene in undisturbed soil samples taken from Picatinny Arsenal, New Jersey. The measured effective diffusion coefficients ranged from 0.0053 to 0.0609 cm2/s over a range of air-filled porosity of 0.23-0.49. The experimental data were compared to several previously published relations that predict diffusion coefficients as a function of air-filled porosity and porosity. A multiple linear regression analysis was developed to determine if a modification of the exponents in Millington's [Science 130 (1959) 100] relation would better fit the experimental data. The literature relations appeared to generally underpredict the effective diffusion coefficient for the soil cores studied in this work. Inclusion of a particle-size distribution parameter, d10, did not significantly improve the fit of the linear regression equation. The effective diffusion coefficient and porosity data were used to recalculate estimates of diffusive flux through the subsurface made in a previous study performed at the field site. It was determined that the method of calculation used in the previous study resulted in an underprediction of diffusive flux from the subsurface. We conclude that although Millington's [Science 130 (1959) 100] relation works well to predict effective diffusion coefficients in homogeneous soils with relatively uniform particle-size distributions, it may be inaccurate for many natural soils with heterogeneous structure and/or non-uniform particle-size distributions.

Original languageEnglish (US)
Pages (from-to)193-208
Number of pages16
JournalJournal of Contaminant Hydrology
Volume56
Issue number3-4
DOIs
StatePublished - 2002

Keywords

  • Diffusion
  • Heterogeneity
  • Trichloroethene
  • Unsaturated zone

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology

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