Microbiological Controls on Geochemical Kinetics 1: Fundamentals and Case Study on Microbial Fe(III) Oxide Reduction

Microbial Iron Redox Cycling in a Circumneutral-pH Groundwater Seep

“…FeOB biomass was assumed to undergo slow first-order decay at a rate (0.05 day Ϫ1 ) typical of low-energy-yield metabolic pathways (26). Dissolved organic carbon (DOC) was released from the decaying FeOB biomass according to a first-order rate constant of 0.1 day wetland sediments (27). The Fe(II) produced was assumed to partition between the aqueous and solid phases according to a simple linear isotherm with a K d (sorption coefficient) of 10, which produced aqueous-/solid-phase Fe(II) ratios consistent with in situ observations.…”

Influence of pH and dissolved Si on Fe isotope fractionation during dissimilatory microbial reduction of hematite

“…The BET surface area was determined to be 10.8 m 2 /g and the particle had an average diameter of 100 nm (determined by TEM). Although hematite is not the most common Fe(III) mineral utilized by iron-reducing bacteria in natural systems (Roden, 2008), it is amenable to partial dissolution by weak HCl as a means for determining the components that have undergone isotopic exchange (Crosby et al, 2005(Crosby et al, , 2007. In addition, among the various Fe(III) oxides, hematite is the only mineral yet studied where the Fe isotope fractionation factors have been determined in abiologic systems to provide a reference frame for interpreting the fractionations produced in biological systems (see Section 4.2).…”

Compendium and synthesis of bacterial manganese reduction rates

“…4A and B, respectively) suggests patterns that are consistent with hyperbolic rate equations (Liu et al, 2001b;Roden, 2008). Monte-Carlo based log-normal regression of such an equation gives the curves shown in Fig.…”