HR: 0800h
AN: H51F-0423    [Abstracts]
TI: Dispersivity of Colloids in Saturated Porous Media is a Function of Colloid Size
AU: * Keller, A A
EM: keller@bren.ucsb.edu
AF: Univ of California, SB, Bren School of Env. Sci. & Mgmt. 3420 Bren Hall, UCSB, Santa Barbara, CA 93106 United States
AU: Auset, M
EM: mauset@bren.ucsb.edu
AF: Univ of California, SB, Bren School of Env. Sci. & Mgmt. 3420 Bren Hall, UCSB, Santa Barbara, CA 93106 United States
AB: Colloid dispersion in porous media is a consequence of the different paths and velocities experienced by the colloids. This work represents a number of studies at the pore and column scales, as well as comparisons to field scale studies. At the pore scale we examined the effect of particle and pore size on colloid dispersion using water-saturated micromodels. Four sizes of colloids were transported at several pressure differences. Image analysis was used to determine particle trajectories, residence times and dispersion coefficients through the micromodels. The magnitude of the dispersion at any given flow rate was found to be controlled by the pore-space geometry and the relative size of colloids with regards to pore channels. Dispersion coefficient and dispersivity decrease with increasing colloid size. Dispersivity is thus not just a function of pore geometry, but depends on colloid characteristics. We corroborated these results with column-scale experiments to observe the effect of transport velocity and colloid size on early breakthrough of free moving colloids. A review of comparable published field studies indicated evidence of early breakthrough of colloids. These findings emphasize the role of particle and pore size on colloidal dispersion and have significant implications for predicting the movement of colloids through saturated porous media.
UR: http://www2.bren.ucsb.edu/~keller/micromodels.htm
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: Fall Meeting 2005