HR: 14:35h
AN: H23H-04    [Abstracts]
TI: Simultaneous in-situ measurements of colloid concentration and water saturation using synchrotron x-rays
AU: * DiCarlo, D A
EM: ddicarlo@ars.usda.gov
AF: USDA/ARS National Sedimentation Laboratory, PO BOX 1157 598 McElroy Dr, Oxford, MS 38655
AU: Dathe, A
EM: ad273@cornell.edu
AF: Cornell University, Dept. of Biological and Environemental Engineering, Ithaca, NY 14853
AU: Giri, S K
EM: skg29@cornell.edu
AF: Cornell University, Dept. of Biological and Environemental Engineering, Ithaca, NY 14853
AU: Zevi, Y
EM: yz59@cornell.edu
AF: Cornell University, Dept. of Biological and Environemental Engineering, Ithaca, NY 14853
AU: Steenhuis, T
EM: tss1@cornell.edu
AF: Cornell University, Dept. of Biological and Environemental Engineering, Ithaca, NY 14853
AB: Simultaneous in-situ measurements of colloid concentration and water saturation are necessary to elucidate the transport properties of colloidal matter in unsaturated flow. Using a synchrotron x-ray source and cadmium tagged colloids we have developed a method to obtain rapid measurements of colloid concentration and water saturation during a rapid flow event. The x-ray source was tuned to an energy of 31.5 KeV which caused the cadmium attached to the colloids to fluoresce at 23.1 KeV. This fluorescence was recorded using a Ge-solid state detector, and detection limits of a few ppm were achieved. Water saturation was measured using x-ray attenuation. Time-lapsed measurements were taken with a sand porous medium undergoing a rapid flow event where the water content increases and then decreases in time. Results show that the cadmium transport was retarded with respect to the water when the cadmium was in solution, but moved with the water phase when it was attached to colloidal particles. Additionally no significant retention of the colloidal particles was found with increasing air/water interfaces (decreasing water saturation) during a flow event.
DE: 1832 Groundwater transport
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting