Transport of colloids in unsaturated porous media

Colloids are small particles below 10 micron. They are found in high concentrations in the soil water. Depending on their stability and mobility the presence of colloids might enhance the transport of strongly adsorbing contaminants such as PAH's and pesticides.
Column experiments are conducted in the laboratory under well-defined and controlled conditions. Latex microspheres are used as model colloids, and washed quartz sand is used as the porous medium. Breakthrough data of a tracer (chloride) and colloids are obtained from homogeneous columns or columns with artificial macropores under different water saturations. The aim is to investigate how water content and soil structure influence colloid transport. The data obtained in the laboratory are interpreted using numerical transport models.