||Robert S. Kerr Environmental Research Lab., Ada, OK. ;ManTech Environmental Technology, Inc., Ada, OK.;Department of Energy, Washington, DC. Environmental Sciences Div.
Colloids are generally defined as inorganic or organic particles with diameters less than 10 microns. Colloidal material may be released from the soil or geologic matrix and transported large distances given favorable hydrological and geochemical conditions. Once released, the primary factors controlling colloidal transport in subsurface systems are colloidal stability, flow rate, and the nature of the solid matrix through which ground water flows. In addition to having a high surface area per unit mass, colloids such as clay minerals and iron oxides are also extremely reactive sorbents for metals and other contaminants. If mobile in subsurface systems, these colloids can effect the migration of sorbed contaminants much larger distances than current transport models would predict. Column experiments were run to determine the effects of pH, flow rate, ionic strength, electrolyte composition, particle size and particle concentration on colloidal stability and transport.