Report Follows

Pharmaceuticals, pathogens, pesticides, and heavy metals often move through soils by the process of colloid or colloid-facilitated transport. Colloids are commonly defined as particles less than 10 μm in diameter that can remain suspended in aqueous solution for considerable amounts of time. Pharmaceuticals, pesticides, and heavy metals are prone to attach to colloids in soils, and pathogenic microorganisms are considered colloids themselves. It is therefore important to understand the mechanisms of colloid transport in soils. The length of time to conduct flow and transport experiments in porous media had led researchers to use centrifuges as tools to evaluate subsurface transport processes. Geocentrifuges are particularly useful to study transport processes in soils, because the flow rates, which are inherently slow in soils, can be sped up considerably. However, there is a need to assure the applicability of geocentrifuges for studying colloid transport