Increasing the efficiency of solute leaching: impacts of flow interruption with drainage of the "preferential flow paths"

Cote, C. M., Bristow, K. L. and Ross, P. J. (2000) Increasing the efficiency of solute leaching: impacts of flow interruption with drainage of the "preferential flow paths". Journal of Contaminant Hydrology, 43 3-4: 191-209. doi:10.1016/S0169-7722(00)00087-5


Author Cote, C. M.
Bristow, K. L.
Ross, P. J.
Title Increasing the efficiency of solute leaching: impacts of flow interruption with drainage of the "preferential flow paths"
Journal name Journal of Contaminant Hydrology   Check publisher's open access policy
ISSN 0169-7722
Publication date 2000
Sub-type Article (original research)
DOI 10.1016/S0169-7722(00)00087-5
Volume 43
Issue 3-4
Start page 191
End page 209
Total pages 19
Place of publication Amsterdam
Publisher Elsevier
Language eng
Abstract Most soils contain preferential flow paths that can impact on solute mobility. Solutes can move rapidly down the preferential flow paths with high pore-water velocities, but can be held in the less permeable region of the soil matrix with low pore-water velocities, thereby reducing the efficiency of leaching. In this study, we conducted leaching experiments with interruption of the flow and drainage of the main flow paths to assess the efficiency of this type of leaching. We compared our experimental results to a simple analytical model, which predicts the influence of the variations in concentration gradients within a single spherical aggregate (SSA) surrounded by preferential flow paths on leaching. We used large (length: 300 mm, diameter: 216 mm) undisturbed field soil cores from two contrasting soil types. To carry out intermittent leaching experiments, the field soil cores were first saturated with tracer solution (CaBr2), and background solution (CaCl2) was applied to mimic a leaching event. The cores were then drained at 25- to 30-cm suction to empty the main flow paths to mimic a dry period during which solutes could redistribute within the undrained region. We also conducted continuous leaching experiments to assess the impact of the dry periods on the efficiency of leaching. The flow interruptions with drainage enhanced leaching by 10-20% for our soils, which was consistent with the model's prediction, given an optimised equivalent aggregate radius for each soil. This parameter quantifies the time scales that characterise diffusion within the undrained region of the soil, and allows us to calculate the duration of the leaching events and interruption periods that would lead to more efficient leaching. Application of these methodologies will aid development of strategies for improving management of chemicals in soils, needed in managing salts in soils, in improving fertiliser efficiency, and in reclaiming contaminated soils. (C) 2000 Elsevier Science B.V. All rights reserved.
Keyword Environmental Sciences
Geosciences, Multidisciplinary
Water Resources
Intermittent Leaching
Preferential Flow
Diffusion
Analytical Solution
Aggregated Porous-media
Mass-transfer
Transport
Diffusion
Soils
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Sustainable Minerals Institute Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 13 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 19 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Mon, 13 Aug 2007, 11:45:11 EST