Unsaturated transport processes in undisturbed heterogeneous porous media. I. Inorganic contaminants

Journal Article · · Soil Science Society of America Journal; (United States)

DOI:https://doi.org/10.2136/sssaj1993.03615995005700040012x· OSTI ID:5698709

Jardine, P M; Jacobs, G K ^[1]; Wilson, G V ^[2]

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1. Oak Ridge National Lab., TN (United States)
2. Univ. of Tennessee, Knoxville, TN (United States)

The objective of this study was to investigate the thermodynamic and kinetic processes controlling the transport of inorganic contaminants in unsaturated, heterogeneous subsurface media. Large undisturbed columns were isolated from a proposed waste site consisting of fractured saprolite (weathered interbedded shale and limestone), and steady-state nonreactive and reactive solute transport experiments were performed at a variety of pressure heads. Observed breakthrough curves (BTC) for binary and ternary mixtures in the Co-Sr-Ca system were delayed relative to nonreactive Br BTC, indicating that the former tracers were adsorbed by the solid phase. Transport of the binary mixtures Co-Ca and Sr-Ca was predicted reasonably well with the equilibrium convective-dispersive (CD) equation using independent measurements of all model parameters. However, application of the nonequilibrium or kinetic CD model to the observed Sr and Co binary data resulted in an improved description of contaminant transport. Cation-exchange equilibria relationships on homogenized subsurface material, using both shake batch and miscible displacement methods, adequately described the thermodynamic processes that were prevalent during contaminant transport. These results suggest that preferential transport of reactive contaminants is negligible for the unsaturated conditions used in this study, and that the structured saprolite within the subsurface media is a chemically active constituent during reactive solute transport. 36 refs., 7 figs., 3 tabs.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5698709
• Journal Information: Soil Science Society of America Journal; (United States), Journal Name: Soil Science Society of America Journal; (United States) Vol. 57:4; ISSN 0361-5995; ISSN SSSJD4
• Country of Publication: United States
• Language: English

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