HR: 08:15h
AN: B51F-02 INVITED     [Abstracts]
TI: Geoelectrical Effects Associated With the Presence of Bacteria in Contaminated Groundwater
AU: * Revil, A
EM: revil@cerege.fr
AF: CNRS-CEREGE, Universit‚ Aix-Marseille 3, Europole de l'Arbois, BP 80, Cedex 4, Aix-en-Provence, 13545 France
AU: Naudet, V
EM: naudet@cerege.fr
AF: CNRS-CEREGE, Universit‚ Aix-Marseille 3, Europole de l'Arbois, BP 80, Cedex 4, Aix-en-Provence, 13545 France
AB: Strong electrical potential anomalies (up to several hundreds of mV) have been evidenced at the ground surface above contaminant plumes rich in organic matter. These electrical disturbances, recordable with non-polarizable electrodes as "self-potential signals", allow to delineate the shape of these plumes and their dynamics. We have investigated the physics behind this geobattery process. Our conclusions are that biofilms, mainly located at the boundaries of the plume where both nutrients and oxygen are available (Monod kinetics), allow the transfer of electrons between the reduced and the oxidized parts of the system. The resulting current density produces electromagnetic disturbances in the Maxwell equations. We show from models, field and sandbox experiments that the electrical potential can be used to determine the redox potential at depth with a minimum of calibration with in situ measurements. Therefore, this method can be used as a redox non-intrusive sensor. The model implies that the areas rich in bacteria are also associated with anomalous high electrical conductivity and induced polarization anomalies as suggested from experiments by E. Atekwana, L. Slater, and co-workers.
UR: http://www.cerege.fr/hydropor/index_hydropor.htm
DE: 4840 Microbiology
DE: 4857 Pollution
DE: 5109 Magnetic and electrical properties
DE: 1831 Groundwater quality
DE: 0925 Magnetic and electrical methods
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting