HR: 0800h
AN: H21D-1046    [Abstracts]
TI: Visualization and Measurement of Colloid Movement and Retention in Unsaturated Media
AU: * Dathe, A
EM: ad273@cornell.edu
AF: Cornell University, Soil and Water Research Group, Riley-Robb Hall, Ithaca, NY 14853 United States
AU: Zevi, Y
EM: yz59@cornell.edu
AF: Cornell University, Soil and Water Research Group, Riley-Robb Hall, Ithaca, NY 14853 United States
AU: Richards, B K
EM: bkr2@cornell.edu
AF: Cornell University, Soil and Water Research Group, Riley-Robb Hall, Ithaca, NY 14853 United States
AU: Steenhuis, T S
EM: tss1@cornell.edu
AF: Cornell University, Soil and Water Research Group, Riley-Robb Hall, Ithaca, NY 14853 United States
AB: To understand the movement and retention of colloids in the vadose zone, it is crucial to investigate processes on the pore scale. Experiments were carried out using a confocal laser scanning microscope which allows acquisition of time series images as well as 3D reconstruction of pore-scale images. Hydrophilic (carboxylated latex) and hydrophobic (polystyrene latex) colloids in aqueous solution stained with rhodamine B were injected into a small horizontal flow chamber packed with fine or coarse quartz sand. The chamber was situated under the microscope which used three spectral channels: a 488 nm (argon) line excites the colloid fluorescence, a 543 nm green (HeNe) line excites rhodamine B fluorescence, and a transmitted light channel that delineates the sand grains. This offers the possibility of finding suitable thresholds for detecting colloidal micropheres and the water phase. Methods of digital image analysis are presented which determine the number and area of moving and retained colloids. The results can be used to verify simulation model parameters concerning colloid transport, such as quantitative measurements for determining collision efficiencies.
DE: 1894 Instruments and techniques
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1875 Unsaturated zone
DE: 1045 Low-temperature geochemistry
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting