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Fritzsche, Andreas ; Bosch, Julian ; Rennert, Thilo ; Heister, Katja ; Braunschweig, Juliane ; Meckenstock, Rainer U. ; Totsche, Kai Uwe:
Fast microbial reduction of ferrihydrite colloids from a soil effluent.
In: Geochimica et Cosmochimica Acta.
Bd. 77
(2012)
.
- S. 444-456.
ISSN 0016-7037
DOI: https://doi.org/10.1016/j.gca.2011.10.037
Abstract
Recent studies on the microbial reduction of synthetic iron oxide colloids showed their superior electron accepting propertyin comparison to bulk iron oxides. However, natural colloidal iron oxides differ in composition from their synthetic counterparts.Besides a potential effect of colloid size, microbial iron reduction may be accelerated by electron-shuttling dissolvedorganic matter (DOM) as well as slowed down by inhibitors such as arsenic. We examined the microbial reduction ofOM- and arsenic-containing ferrihydrite colloids. Four effluent fractions were collected from a soil column experiment rununder water-saturated conditions. Ferrihydrite colloids precipitated from the soil effluent and exhibited stable hydrodynamicdiameters ranging from 281 (±146) nm in the effluent fraction that was collected first and 100 (±43) nm in a subsequentlyobtained effluent fraction. Aliquots of these oxic effluent fractions were added to anoxic low salt medium containing dilutedsuspensions of Geobacter sulfurreducens. Independent of the initial colloid size, the soil effluent ferrihydrite colloids werequickly and completely reduced. The rates of Fe2+ formation ranged between 1.9 and 3.3 fmol h1 cell1, and are in the rangeof or slightly exceeding previously reported rates of synthetic ferrihydrite colloids (1.3 fmol h1 cell1), but greatly exceedingpreviously known rates of macroaggregate-ferrihydrite reduction (0.07 fmol h1 cell1). The inhibition of microbial Fe(III)reduction by arsenic is unlikely or overridden by the concurrent enhancement induced by soil effluent DOM. These organicspecies may have increased the already high intrinsic reducibility of colloidal ferrihydrite owing to quinone-mediated electronshuttling. Additionally, OM, which is structurally associated with the soil effluent ferrihydrite colloids, may also contribute tothe higher reactivity due to increasing solubility and specific surface area of ferrihydrite. In conclusion, ferrihydrite colloidsfrom soil effluents can be considered as highly reactive electron acceptors in anoxic environments.
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| Publikationsform: | Artikel in einer Zeitschrift |
|---|---|
| Begutachteter Beitrag: | Ja |
| Zusätzliche Informationen: | BAYCEER109773 |
| Institutionen der Universität: | Forschungseinrichtungen > Forschungszentren > Bayreuther Zentrum für Ökologie und Umweltforschung - BayCEER Forschungseinrichtungen Forschungseinrichtungen > Forschungszentren |
| Titel an der UBT entstanden: | Ja |
| Themengebiete aus DDC: | 500 Naturwissenschaften und Mathematik |
| Eingestellt am: | 07 Aug 2015 06:59 |
| Letzte Änderung: | 07 Aug 2015 06:59 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/17664 |