HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Mayes, M. A. Articles by Dansby-Sparks, R. PubMed Articles by Mayes, M. A. Articles by Dansby-Sparks, R. Agricola Articles by Mayes, M. A. Articles by Dansby-Sparks, R. Related Collections Laboratory Column Studies Effective Parameters Coupled Flow/Transport Models

SOIL PHYSICS

Influence of Sedimentary Bedding on Reactive Transport Parameters under Unsaturated Conditions

^a Environmental Sciences Division, Oak Ridge National Lab., P.O. Box 2008 MS 6038, Oak Ridge, TN 38731
^b Dep. of Earth and Planetary Sciences, Univ. of Tennessee, Knoxville, TN 37996-1410
^c Dep. of Civil and Environmental Engineering, Univ. of Tennessee, 62 Perkins Hall, Knoxville, TN 37996-2010
^d Dep. of Chemistry, Univ. of Tennessee, 552 Buehler Hall, Knoxville, TN 37996-1600

^* Corresponding author (mayesma{at}ornl.gov).

Moisture and contaminant transport in partially saturated, heterogeneous, layered sediments is typically anisotropic. Solute transport parameters, including dispersivity and the adsorption coefficient, and the modeled concentration of reactive minerals may depend on the direction of flow with respect to sedimentary layering. Reaction rates, in contrast, should be independent of flow direction. We determined the influence of flow direction on transport parameters for nonreactive (Br^–) and reactive (cobalt ethylenediaminetetraacetic acid [Co(II)EDTA^2–]) solutes under partially saturated conditions by imposing flow either parallel to or across sedimentary bedding in 11 intact sediment cores of various textures. Higher dispersivity of nonreactive tracers in parallel-bed cores suggested fluid channeling through permeable layers, while low-conductivity layers dampened channeling in cross-bed samples. Rates of transformation of Co(II)EDTA^2– into Co(III)EDTA^– and of disassociation of Co²⁺ and EDTA^4– were modeled assuming that the reaction rates were independent of the flow direction. The concentration of Mn oxides that was responsible for the transformation reaction was dependent on the flow direction, which governed the extent of contact between the solution and the solid phase. Similarly, the adsorption constants of Co(II)EDTA^2– and Co(III)EDTA^– were dependent on the flow direction but were also unique for each experiment. The modeled concentration of reactive minerals was the most sensitive parameter describing the reaction and transformation of Co(II)EDTA^2–.

Abbreviations: DOE, Department of Energy • EDTA, ethylenediaminetetraacetic acid • HC, Hanford Coarse • HD, Hanford Dike • HI, Hanford Interbedded • HL, Hanford Laminated • LS/S, Ringold Lower Silts/Sands