HR: 0800h
AN: V51A-0516    [Abstracts]
TI: Fe Isotope Fractionation: Effect of Desferrioxamine Mesylate (DFAM) and Reduction of Goethite by Total Membrane Fraction of {\it Shewanella oneidensis}
AU: * Jang, J
EM: jehun@psu.edu
AF: Geosciences, 503 Deike building The Pennsylvania State University, University Park, PA 16802 United States
AU: Mathur, R
EM: MATHUR@juniata.edu
AF: Geology, Juniata College, Hungtingdon, PA 16652 United States
AU: Liermann, L
EM: ljl8@psu.edu
AF: Geosciences, 503 Deike building The Pennsylvania State University, University Park, PA 16802 United States
AU: Ruebush, S
EM: ssr123@psu.edu
AF: Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802 United States
AU: Tien, M
EM: mxt3@psu.edu
AF: Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802 United States
AU: Brantley, S
EM: brantley@essc.psu.edu
AF: Geosciences, 503 Deike building The Pennsylvania State University, University Park, PA 16802 United States
AB: In both abiotic adsorption of Fe(II) on goethite and reduction of goethite by total membrane fraction of {\it Shewanella oneidensis} ({\it in vitro} reduction), addition of the strong Fe chelator (desferrioxamine mesylate, DFAM) affected the fractionation of Fe isotopes. In order to see the effect, we measured the \Delta$^{56/54}$Fe$_{aq}$, defined as \delta$^{56/54}$Fe$_{aq}$ - \delta$^{56/54}$Fe$_{source}$, where \delta$^{56/54}$Fe$_{source}$ is the isotopic composition of either goethite or the adsorption control solution. With DFAM, the values of \Delta$^{56/54}$Fe$_{aq}$ were more positive than \Delta$^{56/54}$Fe$_{aq}$ values measured without DFAM, which indicates that aqueous Fe(II) is enriched with $^{56}$Fe(II) compared to the Fe sources in the presence of DFAM. It is notable that {\it in vitro} reduction showed that the membrane fraction also could have a similar effect as DFAM does. We also observed that the adsorbed Fe(II) on goethite in the experiment without DFAM or membrane became isotopically heavier (enriched with $^{56}$Fe(II)) in 7 days. In comparison, in the DFAM and membrane experiments, the adsorbed Fe was not as isotopically heavy, though similar trend was observed.
DE: 1040 Isotopic composition/chemistry
DE: 1045 Low-temperature geochemistry
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting