A modified Monod rate law for predicting variable S isotope fractionation as a function of sulfate reduction rate

Modelling the Effects of Non-Steady State Transport Dynamics on the Sulfur and Oxygen Isotope Composition of Sulfate in Sedimentary Pore Fluids

“…The oxygen isotope composition of extracellular sulfate is dominated by the rapid, intracellular, exchange of oxygen atoms in intermediate-valence state sulfur species with the ambient water, which ultimately drives δ 18 O SO4 to reflect the pore water value plus the oxygen isotope fractionation of this isotope-exchange. In this way, the residual sulfate pool becomes increasingly enriched in the heavier isotopes as MSR progresses (Böttcher et al, 1998;Böttcher et al, 1999;Canfield, 1998;Wortmann et al, 2001;Canfield et al, 2010;Sim et al, 2011a;Müller, 2013;Wankel et al, 2014;Wing and Halevy, 2014;Giannetta et al, 2019;Bertran et al, 2020;Pellerin et al, 2020). Other processes are known to affect the sulfur and oxygen isotope compositions of marine sediments, chiefly; sulfide and pyrite oxidation (Balci et al, 2007;Brunner et al, 2008;Heidel and Tichomirowa, 2011;Kohl and Bao, 2011;Jørgensen et al, 2019), disproportionation Böttcher et al, 2005;Blonder et al, 2017), and the anaerobic oxidation of methane (Antler et al, 2013;Antler et al, 2014;Antler et al, 2015;Deusner et al, 2014) but we do not consider them further in this study.…”