HR: 0801h
AN: NS11B-0500    [Abstracts]
TI: Electrical potential source mechanisms in microbial induced sulfate reducing environments
AU: * Zhang, C
EM: chizhang@pegasus.rutgers.edu
AF: Dept. of Earth & Environmental Sciences, Rutgers University, Newark, Smith Hall, 101 Warren Street, Newark, NJ 07102, United States
AU: Slater, L
EM: lslater@andromeda.rutgers.edu
AF: Dept. of Earth & Environmental Sciences, Rutgers University, Newark, Smith Hall, 101 Warren Street, Newark, NJ 07102, United States
AU: Ntarlagiannis, D
EM: d.ntarlagiannis@qub.ac.uk
AF: School of Planning, Architecture and Civil Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Queen's University Belfast, Belfast, BT9 5AG, United Kingdom
AU: Singh, K
EM: ksingh03@qub.ac.uk
AF: School of Planning, Architecture and Civil Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Queen's University Belfast, Belfast, BT9 5AG, United Kingdom
AU: Doherty, R
EM: r.doherty@qub.ac.uk
AF: School of Planning, Architecture and Civil Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Queen's University Belfast, Belfast, BT9 5AG, United Kingdom
AB: In order to compare self-potential (SP) signals resulting from possible ‘geobattery' effects with electrodic potential signals based on a known galvanic cell (GC) effect in the presence of sulfide, we designed a column experiment using dual sensor Ag-AgCl electrodes. Water from the Langan River (Belfast, UK), known to contain a sulfate reducing microbial community, was obtained. Two experimental columns were packed with fine-grained glass beads. One column continuously circulated (closed loop) with autoclaved river water as a control, while the other retained biologically active natural river water. Six Ag-AgCl electrodes equally spaced along one side of each column, and three Ag-AgCl self potential electrodes (where the metal is in electrolytic contact with the column via a sterilized 1M KCl agar gel), were placed on the other side of each column. Electrical potential signals were continuously recorded with both sensor types. Induced polarization, electrical resistivity, temperature and aqueous geochemistry measurements (pH, Eh, and conductivity) were taken once daily. Over the 20 day experiment duration, darkening of the circulating fluid, biofilm formation and a sulfurous smell were observed in the biologically active column whereas no such color change (or smell) was observed for the control column. In the active column electrodic potential readings approached 570 mV whereas stable and small electrodic potential values (~8 mV) were detected in the control column.. Self potential signals were consistently only 1-8 mV in both columns. The experiment shows although electrodic potentials (at the electrode) are diagnostic of microbial driven sulfate reduction there is no measurable self potential (geobattery) effect associated with this microbial process.
DE: 0416 Biogeophysics
DE: 0418 Bioremediation
DE: 1835 Hydrogeophysics
SC: Near-Surface Geophysics [NS]
MN: 2007 Fall Meeting