Unsaturated flow effects on solute transport in porous media
Abstract
A major contaminant transport process in soils is hydrodynamic dispersion by affecting the spreading and arrival of surface-applied pollutants at underlying groundwater reservoirs. When a soil is unsaturated, hydrodynamic dispersion is very much affected by soil water saturation. Centimeter- and decimeter-scale column experiments were carried out to explore the effects of fluid saturation and particle size on the unsaturated solute dispersivity. Measured in-situ breakthrough curves were analyzed in terms of both classical advection-dispersion and dual-porosity (mobile-immobile) type transport equations. A clear non-monotonic relationship was found between the dispersivity and soil water saturation. The extent of non-monotonicity was more pronounced for a relatively coarse-textured sand compared to a finer sand. This finding has been reported rarely before; it explains some of the inconsistencies of saturation-dispersivity relationships in the literature.
- Publication:
-
Journal of Hydrology
- Pub Date:
- July 2021
- DOI:
- 10.1016/j.jhydrol.2021.126301
- Bibcode:
- 2021JHyd..59826301Z
- Keywords:
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- Dispersion;
- Dispersivity;
- Solute transport;
- Unsaturated zone