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

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Vanderborght, J. Articles by Vereecken, H. Search for Related Content PubMed Articles by Vanderborght, J. Articles by Vereecken, H. GeoRef GeoRef Citation Agricola Articles by Vanderborght, J. Articles by Vereecken, H. Related Collections Solute Transport Models Dispersion Vadose Zone Risk Assessment Vadose Zone Processes and Chemical Transport

ORIGINAL RESEARCH

One-Dimensional Modeling of Transport in Soils with Depth-Dependent Dispersion, Sorption and Decay

Agrosphere, ICG-IV Forschungszentrum Jülich GmbH, D 52425 Jülich, Germany
^* Corresponding author (j.vanderborght{at}fz-juelich.de)

Received 21 July 2006.

Macroscopic spatial variations in advection velocity lead to an increase in dispersion with increasing travel distance or depth. In soils, this increase goes along with a decrease in decay and sorption of organic substances. We used three different one-dimensional models that make different assumptions about the dispersion process to compare predicted leaching in a 1-m-deep soil profile with layers with different sorption and decay parameters. The first two convective–dispersive models assume that dispersion results from microscopic variations in solute particle velocities that are not correlated across soil layer boundaries. The third model, a stream tube model (STM), assumes that the particle velocity remains constant along its trajectory and is perfectly correlated in different layers. The three models were parameterized to predict the same inert tracer breakthrough curve (BTC) at 1-m depth. The first convective–dispersive model assumes a constant dispersion coefficient ("homogeneous" convection–dispersion equation [CDE]). The second model uses different dispersion coefficients in the different layers ("layered" CDE) to predict the same inert tracer BTCs as the STM at the layer boundaries. Despite similar predictions of inert tracer BTCs, the models predicted different BTCs of reactive substances at 1-m depth. The different predictions by the STM and layered CDE illustrate the importance of the correlation of solute particle velocities in different soil layers. They also point to a fundamental problem related to the use of a CDE with a depth-dependent dispersion to mimic a dispersion process caused by macroscopic variations in particle velocities.

Abbreviations: BTC, breakthrough curve • CDE, convection–dispersion equation • STM, stream tube model