Colloid-facilitated transport designates a transport process by which colloidal particles serve as transport vector[1] of diverse contaminants in the surface water (sea water, lakes, rivers, fresh water bodies) and in underground water circulating in fissured rocks[2] (limestone, sandstone, granite, ...).
The transport of colloidal particles in surface soils and in the ground can also occur, depending on the soil structure, soil compaction, and the particles size, but the importance of colloidal transport was only given sufficient attention during the 1980 years.
[3] Radionuclides, heavy metals, and organic pollutants, easily sorb onto colloids suspended in water and that can easily act as contaminant carrier.
Colloids have been suspected for the long range transport of plutonium on the Nevada Nuclear Test Site.
However, the mobility of inorganic colloids is very low in compacted bentonites and in deep clay formations[4] because of the process of ultrafiltration occurring in dense clay membrane.