HR: 0800h
AN: H21D-1045    [Abstracts]
TI: Epi-fluorescence Imaging of Colloid Transport in Porous Media
AU: * Zhang, P
EM: pzhang@sci.ccny.cuny.edu
AF: City College of New York, Dept. of Earth and Atmospheric Sciences, 138th St. and Convent Ave., New York, NY 10031 United States
AU: Olin, A
EM: cosmicao@hotmail.com
AF: City College of New York, Dept. of Earth and Atmospheric Sciences, 138th St. and Convent Ave., New York, NY 10031 United States
AB: The lack of direct, continuous observation of the movement of colloids in porous/fractured media limits our knowledge of the processes that control colloid transport and immobilization in these media. Here we used a non-invasive epi-fluorescence imaging technique to continuously monitor the transport of fluorescent colloids in a flow chamber (10-cm wide by 18-cm long by 0.9-cm thick) packed with translucent quartz sand (20-30 or 40-60 mesh). The use of epi-illumination, as opposed to trans-illumination used in other fluorescence imaging systems, minimizes the direct input of excitation light to the cooled CCD-camera and hence significantly enhances the signal to noise ratio. Fluorescence intensities increased linearly as the thickness of the sand (saturated with 1E7 spheres/mL of micron-sized fluorescent latex microspheres) increased from 3 mm to 9 mm, indicating that the excitation light was able to penetrate the saturated sand up to 9 mm. When the sand (9 mm thick) was saturated with microsphere suspension of various concentrations, fluorescence intensities increased linearly as the microsphere concentration increased from 1E6 to 5E7 spheres/mL. The imaging system was also able to detect about 2E7 cells/mL of Escherichia coli (stained with carboxyfluorescein diacetate succinimidyl ester, CFDA SE) in saturated quartz sand, with a dynamic range of over two orders of magnitude. The transport and immobilization of florescent colloids in packed quartz sand (homogeneous as well as with conductivity contrasts) will be discussed.
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting