https://doi.org/10.5194/bg-2020-73 Preprint. Discussion started: 17 March 2020 c Author(s) 2020. CC BY 4.0 License. 1 Impact of reactive surfaces on the abiotic reaction between nitrite and 2 ferrous iron and associated nitrogen and oxygen isotope dynamics 3 Anna-Neva Visser1,4, Scott D. Wankel2, Pascal A. Niklaus3, James M. Byrne4, Andreas A. Kappler4, 4 Moritz F. Lehmann1 5 1Department of Environmental Sciences, Basel University, Bernoullistrasse 30, 4056 Basel, Switzerland 6 2Woods Hole Oceanographic Institution, Woods Hole, 360 Woods Hole Rd, MA 02543, USA 7 3Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, 8 Switzerland 9 4Department of Geosciences, Tübingen University, Hölderlinstrasse 12, 72074 Tübingen, Germany 10 Correspondence to: Anna-Neva Visser (
[email protected]) 11 Abstract. Anaerobic nitrate-dependent Fe(II) oxidation (NDFeO) is widespread in various aquatic environments, and plays a 12 major role in iron and nitrogen redox dynamics. However, evidence for truly enzymatic, autotrophic NDFeO remains limited, 13 with alternative explanations involving coupling of heterotrophic denitrification with abiotic oxidation of structurally-bound 14 or aqueous Fe(II) by reactive intermediate N species (chemodenitrification). The extent to which chemodenitrification is 15 caused, or enhanced, by ex vivo surface catalytic effects has, so far, not been directly tested. To determine whether the presence 16 of either a Fe(II)-bearing mineral or dead biomass (DB) catalyses chemodenitrification, two different sets of anoxic batch 17 experiment were conducted: 2 mM Fe(II) was added to a low-phosphate medium, resulting in the precipitation of vivianite - 8 - 18 (Fe3(PO4)2), to which later 2 mM nitrite (NO2 ) was added, with or without an autoclaved cell suspension (~1.96×10 cells ml 1 2+ 19 ) of Shewanella oneidensis MR-1.