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Fritzsche, A.* ; Bosch, J. ; Sander, M.* ; Schröder, C.* ; Byrne, J.M.* ; Ritschel, T.* ; Joshi, P.* ; Maisch, M.* ; Meckenstock, R.U. ; Kappler, A.* ; Totsche, K.U.*

Organic matter from redoximorphic soils accelerates and sustains microbial Fe(III) reduction.

Environ. Sci. Technol. 55, 10821-10831 (2021)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
Microbial reduction of Fe(III) minerals is a prominent process in redoximorphic soils and is strongly affected by organic matter (OM). We herein determined the rate and extent of microbial reduction of ferrihydrite (Fh) with either adsorbed or coprecipitated OM by Geobacter sulfurreducens. We focused on OM-mediated effects on electron uptake and alterations in Fh crystallinity. The OM was obtained from anoxic soil columns (effluent OM, efOM) and included-unlike water-extractable OM-compounds released by microbial activity under anoxic conditions. We found that organic molecules in efOM had generally no or only very low electron-accepting capacity and were incorporated into the Fh aggregates when coprecipitated with Fh. Compared to OM-free Fh, adsorption of efOM to Fh decelerated the microbial Fe(III) reduction by passivating the Fh surface toward electron uptake. In contrast, coprecipitation of Fh with efOM accelerated the microbial reduction, likely because efOM disrupted the Fh structure, as noted by Mössbauer spectroscopy. Additionally, the adsorbed and coprecipitated efOM resulted in a more sustained Fe(III) reduction, potentially because efOM could have effectively scavenged biogenic Fe(II) and prevented the passivation of the Fh surface by the adsorbed Fe(II). Fe(III)-OM coprecipitates forming at anoxic-oxic interfaces are thus likely readily reducible by Fe(III)-reducing bacteria in redoximorphic soils.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords Dom ; Mössbauer Spectroscopy ; Dissolved Organic Matter ; Electron-accepting Capacity ; Ferrihydrite ; Iron Oxide ; Mediated Electrochemical Reduction; Humic Substances; Iron(iii) Oxyhydroxides; Mossbauer-spectroscopy; Electron-acceptors; Ferrous Iron; Ferrihydrite; Oxide; Carbon; Reactivity; Exopolysaccharides
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Journal Environmental Science & Technology
Quellenangaben Volume: 55, Issue: 15, Pages: 10821-10831 Article Number: , Supplement: ,
Publisher ACS
Publishing Place Washington, DC
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Institute of Groundwater Ecology (IGOE)