Interactions Between Fe(III) - Reducing Bacteria and Fe Oxides: Microbial and Geochemical Dissolution Controls (Zachara BES-oxide), PNNL Scope #28036)
EMSL Project ID
4593
Abstract
Investigate electron transfer mechanisms involved in bacterial Fe(III) oxide reduction.Work authorization text added 08/11/05:
Fe(III) oxides poise the oxidation/reduction potential of subsurface materials and act as electron acceptors for redox reactions. Dissimilatory metal reducing bacteria (DMRB) utilize these oxides as electron acceptors, and transform them to other mineral phases. Research is proposed to evaluate mineral transformations of Fe(III) oxides by biogeochemical reductants and DMRB in physical and mineralogic configurations representative of in-situ conditions, including multi-mineral grain coatings and intragrain precipitates in lithic fragments. These characteristic microenvironments limit direct organism-Fe(III) oxide contact, and provide a unique physicochemical setting for biotransformation that has not been scientifically explored. Laboratory physical models involving precipitated nanoparticulate Fe(III) oxides in porous silica, and layered Fe(III) oxides and other accessory phases on quartz slides will allow study of biotransformation reactions under controlled conditions that simulate lithic fragment interiors and grain coatings. Hypotheses will be evaluated in batch and flow systems incubated with diffusible biogeochemical reductants or DMRB that have been cultured under electron acceptor limited conditions. Physical model results will be used to interpret the biotransformation of Fe(III) oxides in subsurface sediments containing particle coatings and intragrain precipitates. High resolution scanning and transmission electron microscopies, Mössbauer spectroscopy, conventional and synchrotron x-ray diffraction, XANES spectromicroscopy, and atomic force microscopy will be used to monitor reductant and microbe induced changes to the Fe(III) oxides. Contact John Zachara, project manager, for additional information. Assumptions - The DOE client (Basic Energy Sciences) expects us to conduct fundamental research to further our knowledge in areas of importance to DOE's mission, and to disseminate this knowledge through publications in peer-reviewed journals and presentations of results at scientific meetings. Products/Deliverables: - Publications in scientific journals - Presentations at scientific meetings and symposia.
Project Details
Project type
Exploratory Research
Start Date
2003-08-15
End Date
2007-06-03
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members