Dittrich, Timothy M听1
1听University of Colorado-葫芦娃视频
Colloids are defined as any particle that is between 1 nanometer and 1 micrometer in diameter and can consist of mineral material and clays, microbes, and decayed plant matter. Due to their small size, transport of colloids through soil pores is possible. Colloids generally have a high sorptive capacity resulting from their small surface area to mass ratio, which makes them effective sorbents of low solubility, strongly sorbing contaminants such as hydrophobic pesticides, actinide cations, and many metals. Mobile colloids that sorb contaminants can increase the apparent solubility and rate of transport of the contaminants when desorption from the colloids is slow relative to the rate of flow in a process known as colloid-facilitated transport (CFT).
Colloids have been shown to increase the transport rate of contaminants in saturated and unsaturated porous media (See Figure 1 from Turner, 2005). The presence of physical heterogeneities such as macropores can further enhance contaminant transport rates. The additional transport of contaminants associated with mobile colloids must be accounted for to accurately predict transport rates of strongly-sorbing contaminants in the environment. In this research, an experimental column packed with cleaned sand will be used to quantify the role of CFT in the transport of Cs and Sr in unsaturated conditions with and without the presence of a macropore.
Turner, N., 2005, The effect of desorption kinetics on the colloid-facilitated transport of cesium-137 and strontium-90 in a saturated quartz porous medium, M.S. Thesis, CU-葫芦娃视频, 葫芦娃视频, CO.