Abstract
Estimating contaminant migration in the context of waste disposal and/or environmental remediation of polluted soils requires a complete understanding of the underlying transport processes. In unsaturated porous media, water content is one of the most determining parameters to describe solute migration because it impacts directly on solute pore velocity. However, numerous studies are satisfied with only a global or a partial spatial distribution of water content within the studied porous media. Therefore, distribution of water content in porous media must be precisely achieved to optimize transport processes modeling. Tracer experiments with downward flow were performed on the BEETI experimental device equipped with a sand column. Water content and concentration profiles of tracer (KI) were measured along the column during experiment. The relative dispersion of water content, calculated along the column, gives an idea of influence of this parameter on transport properties. A relationship between pore velocity, Darcy flow velocity and water content is proposed.
Highlights
The prediction of contaminant migration in the context of waste disposal or environmental remediation of polluted soils requires a complete understanding of the underlying transport processes
Retention curves record local fluctuations of water contents that cannot be related to sand grain stacking, seeing the sand bulk density distribution measured by dichromatic X-ray spectrometer (DXS)
Solute transport experiments performed with BEETI device show that water content, Darcy flow velocity and tracer pore velocity cannot take simultaneously uniform values within a homogeneous packed sand column
Summary
The prediction of contaminant migration in the context of waste disposal or environmental remediation of polluted soils requires a complete understanding of the underlying transport processes. In permeable porous media such as soils or sands, which are commonly found in environmental applications, hydrodynamic dispersion always plays a relevant role in determining the fate of transport processes. The liquid spreads over the solid surface and forms a continuous and connected liquid, fulfilling partially the porous space. It is through this connected configuration, that capillary flow takes place, described by the Richard’s equation [2]. Depending on their sizes, pores are fully or partially filled of water. Films may significantly participate in spreading, and give tracer particles opportunities of being arrested
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