title: Physical and chemical determinants of colloid transport and deposition in water-unsaturated sand and Yucca Mountain tuff material.
abstract: Colloid mobility was determined in a system consisting of quartz sand or crushed Yucca Mountain tuff, simulated groundwater (J-13), and hydrophilic latex particles. Water content (theta) and ionic strength (I; DI water, 0.1x, 1x, 10x groundwater dilution) were manipulated to define limiting conditions for colloid transport atthe Yucca Mountain site. Colloid transport, measured with a centrifuge method at relatively high theta (saturation >36% for sand, >62% for crushed tuff) in DI water, was equivalent to transport at 100% saturation measured with conventional columns. When variables were isolated, increasing I and decreasing theta resulted in a greater extent of colloid deposition; I was more important at higher theta; physical properties were more important at lower theta. I and theta had an interactive effect on colloid deposition whereby synergism was generally observed, especially for simulated groundwater (1x); antagonism was observed at 10x groundwater dilution. At 19% moisture saturation on the crushed tuff, a decreasing rate of colloid deposition was observed. This corresponded to a hydrodynamic condition of 79% immobile water where solute tracers were excluded from a fraction of the pore volume. This suggests that a portion of the favorable sites for deposition were associated with the excluded or immobile water domain and were not accessible to colloids.
authors: Department of Chemistry, Washington State University, Richland 99352, USA. apg@tricity.wsu.edu
authors: A P
authors: AP
authors: Gamerdinger
authors: D I
authors: DI
authors: Kaplan
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003102:Colloids / Q000032:analysis*; D004784:Environmental Monitoring; D010316:Particle Size; D011791:Quartz; D012822:Silicon Dioxide; D012989:Soil Pollutants / Q000032:analysis*; D014872:Water Movements
chemical_list: D003102:Colloids; D012989:Soil Pollutants; D011791:Quartz; D012822:Silicon Dioxide