HR: 0830h
AN: NS51B-06    [Abstracts]
TI: Electrical Measurements on Microbial Cells in Suspension and in Sand Columns
AU: * Ntarlagiannis, D
EM: dimntar@pegasus.rutgers.edu
AF: Rutgers University, Department of Earth and Environmental Sciences, 101 Warren Street, Smith Hall, Newark, NJ 07102 United States
AU: Yee, N
EM: nyee@andromeda.rutgers.edu
AF: Rutgers University, Department of Earth and Environmental Sciences, 101 Warren Street, Smith Hall, Newark, NJ 07102 United States
AU: Slater, L
EM: lslater@andromeda.rutgers.edu
AF: Rutgers University, Department of Earth and Environmental Sciences, 101 Warren Street, Smith Hall, Newark, NJ 07102 United States
AU: Atekwana, E
EM: atekwana@umr.edu
AF: University of Missouri-Rolla, Department of Geological Sciences & Engineering, School of Materials, Energy & Earth Resources University of Missouri-Rolla, 125 McNutt Hall, Rolla, MO 65409 United States
AB: Recent studies show that microbial processes impact the electrical properties of earth materials. However the mechanisms generating the observed electrical signatures remain uncertain. The addition of microbial cells will increase the total surface area and surface charged density of a soil. Biofilms may coat soil surfaces and alter the electrical properties of the mineral-fluid interface. We attempted to detect the presence of microbial cells in suspensions and in sand columns with four electrode geophysical measurements. Cell cultures of Shewanella putrefaciens and Escherichia coli (up 5g/l dry weight) were suspended in NaNO3 electrolyte solutions of varying ionic strength (0.1 M - 0.001 M). Similar suspensions were later injected into Ottawa sand columns. Electrical measurements (impedance magnitude and phase shift) were made from 0.05 Hz - 10 kHz with all datasets calibrated to known solutions. The impact of the microbial cells on the suspension conductivity was detectable only at the very lowest electrolyte concentrations. Any effect on the phase shift was beyond the detection limit of the geophysical instrumentation in all experiments due to the dominance of the conduction term over the polarization. Our results suggest that the increased conduction and polarization observed with geophysical methods at microbial active hydrocarbon sites may not be directly related to the microbial population itself.
DE: 0400 Biogeosciences
DE: 0925 Magnetic and electrical methods
DE: 0933 Remote sensing
DE: 1615 Biogeochemical processes (4805)
SC: Near-Surface Geophysics [NS]
MN: 2005 Joint Assembly