HR: 1330h
AN: B32A-0375    [PDF]
TI: Framework for Numerical Simulation of Bacterial Fe(III) Oxide Reduction in Circumneutral Soil and Sedimentary Environments
AU: Roden, E E
EM: eroden@bsc.as.ua.edu
AF: The University of Alabama, Department of Biological Sciences, Tuscaloosa, AL 35487-0206 United States
AU: * Sedo, E
EM: sedo001@bama.ua.edu
AF: The University of Alabama, Department of Biological Sciences, Tuscaloosa, AL 35487-0206 United States
AB: Studies of synthetic and natural Fe(III) oxide reduction by pure cultures of the dissimilatory Fe(III)-reducing bacteria (FeRB) Shewanella putrefaciens and Geobacter sulfurreducens have been used to develop a framework for numerical simulation of bacterial Fe(III) oxide reduction in circumneutral soil and sedimentary environments. Experimental data show that surface area-normalized rates of electron transfer to Fe(III) oxides are comparable (in the presence of excess electron donor) across a wide range of oxide crystal structure and surface area. These results suggest a rate model in which enzymatic electron transfer is directly dependent on the abundance of reducible oxide surface sites. Studies of the influence of FeRB density on rates of oxide reduction kinetics demonstrate a hyperbolic relationship between total cell density and surface-area normalized reduction rate; additional experiments to assess the relationship between reduction rate and the abundance of FeRB attached or adhered to oxide surfaces are underway. The results of these studies, together with data on FeRB growth yield, provide information required for simulation of oxide reduction kinetics in nonsteady-state systems in which FeRB cell density varies over time. Finally, previous and ongoing studies of Fe(II) sorption to residual Fe(III) oxide and other mineral surfaces during enzymatic reduction permit development of a semi-empirical, reaction-based approach for depicting the influence of surface-bound Fe(II) accumulation on long-term oxide reduction kinetics. The developed model accurately reproduces the results of batch and column studies of synthetic and natural Fe(III) oxide reduction, and can be used to assess the impact of field-scale physical and/or chemical heterogeneity on spatial and temporal patterns of bacterial Fe(III) oxide reduction.
DE: 0400 Biogeosciences
DE: 1045 Low-temperature geochemistry
SC: Biogeosciences [B]
MN: 2003 Fall Meeting