HR: 1340h
AN: B33C-1046    [Abstracts]
TI: Kinetics of Microbial Fe(III) Reduction: From the Laboratory to the Field
AU: Bonneville, S
EM: s.bonneville@geo.uu.nl
AF: Department of Earth Sciences - Geochemistry Utrecht University, P.O. Box 80021, Utrecht, TA 3508 Netherlands
AU: * Van Cappellen, P
EM: pvc@geo.uu.nl
AF: Department of Earth Sciences - Geochemistry Utrecht University, P.O. Box 80021, Utrecht, TA 3508 Netherlands
AU: Behrends, T
B33C-1046 AF: Department of Earth Sciences - Geochemistry Utrecht University, P.O. Box 80021, Utrecht, TA 3508 Netherlands
AU: Hyacinthe, C
B33C-1046 AF: Department of Earth Sciences - Geochemistry Utrecht University, P.O. Box 80021, Utrecht, TA 3508 Netherlands
AB: A kinetic model for the direct microbial reduction of Fe(III)solids in the presence of excess electron donor is presented. The model assumes a two-step mechanism: (i) mutual attachment of Fe(III) solids and cells, and (ii) reduction of Fe(III) centers at the surface of attached mineral particles. The validity of the model is tested using Shewanella putrefaciens and nanohematite as model dissimilatory iron reducing bacteria and Fe(III) solid, respectively. The results demonstrate that the iron reduction rates correlate linearly with the relative coverage of the cell surface by nanohematite, hence supporting a direct electron transfer from membrane-bound reductases to the mineral surface. The model is extended to the reduction by S. putrefaciens of other Fe(III) oxyhydroxides, as well as Fe(III)-rich natural sediments. The maximum reduction rates per cell of Fe(III)oxyhydroxides are shown to correlate with the solubility of the solid phases, while the half-saturation constants depend on the solid to cell ratio. The implications of the laboratory-based kinetics for including microbial iron reduction in reactive transport models of natural porous media are discussed.
DE: 0409 Bioavailability: chemical speciation and complexation
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 0448 Geomicrobiology
DE: 0471 Oxidation/reduction reactions (4851)
SC: Biogeosciences [B]
MN: Fall Meeting 2005