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This article in JEQ

  1. Vol. 30 No. 2, p. 573-583
     
    Received: Dec 16, 1999
    Published: Mar, 2001


    * Corresponding author(s): ghodrati@nature.berkeley.edu
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doi:10.2134/jeq2001.302573x

Detailed Characterization of Solute Transport in a Heterogeneous Field Soil

  1. Fernando Garridoa,
  2. Masoud Ghodrati *b,
  3. Chris G. Campbellb and
  4. Michael Chendorainb
  1. a Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Científicas, Serrano 115-dup. E-28006-Madrid, Spain
    b Ecosystem Sciences Division, Dep. of Environmental Science Policy and Management, Univ. of California, 151 Hilgard Hall, Berkeley, CA 94720-3110

Abstract

There is a necessity for improved physical understanding of solute transport processes in heterogeneous soil systems. In situ nondestructive techniques like time domain reflectometry (TDR) and fiber optic miniprobes (FOMPs) permit the collection of unique measurements of solute transport processes in soils for the purposes of model development and validation. This study examined the application of TDR and FOMPs to measure solute transport at various points laterally and at two depths in a heterogeneous clay-loam soil. A miscible displacement experiment was performed at a constant irrigation flux to examine the applicability of these probes to field soils. In their first application to a field soil, the FOMPs were successfully calibrated and performed well in measuring solute breakthrough curves. Two flow regimes were identified in the soil profile, the first where lateral spreading of the solute occurred in the surface horizon, followed by convergence into preferential flow pathways in the second transport zone. The measured transport response was heterogeneous with at least two identifiable vertical flow phases. It was demonstrated using transfer function modeling and data from a corresponding laboratory study that the FOMPs were measuring the slower phase, while the TDR probes captured a composite of the fast and slow phases. The combination of these two techniques may be a means to separate solute transport phases in heterogeneous media and relate laboratory column results to field studies.

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Copyright © 2001. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.30:573–583.