title: Biochar-Facilitated Microbial Reduction of Hematite.
abstract: As an important component of soil organic matter (SOM), the transformation of pyrogenic carbon plays a critical role in the biogeochemical cycles of carbon and other redox-active elements such as iron (Fe). Herein, we studied the influences of wheat straw-derived biochars on the microbial reduction of 100 mM of hematite by the dissimilatory metal reducing bacteria Shewanella oneidensis MR-1 under anoxic conditions. The long-term microbial reduction extent and initial reduction rate of hematite were accelerated by more than 2-fold in the presence of 10 mg L(-1) biochar. Soluble leachate from 10 mg L(-1) biochar enhanced Fe(III) reduction to a similar degree. Microbially prereduced biochar leachate abiotically reduced hematite, consistent with the apparent electron shuttling capacity of biochar leachate. Electron paramagnetic resonance (EPR) analysis suggested that biochar leachate-associated semiquinone functional groups were likely involved in the redox reactions. In addition to electron shuttling effects, biochar particles sorbed 0.5-1.5 mM biogenic Fe(II) and thereby increased the long-term extent of hematite reduction by 1.4-1.7 fold. Our results suggest that Fe redox cycling may be strongly impacted by pyrogenic carbon in soils with relatively high content of indigenous pyrogenic carbon or substantial application of biochar.
authors.affiliation: Department of Civil and Environmental Engineering, University of Nevada , Reno, Nevada 89557, United States.
authors.forename: Shengnan
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Civil and Environmental Engineering, University of Nevada , Reno, Nevada 89557, United States.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Adhikari
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332-0340, United States.
authors.forename: Rixiang
authors.initials: R
authors.lastname: Huang
authors.affiliation: Department of Civil and Environmental Engineering, University of Nevada , Reno, Nevada 89557, United States.|College of Environmental Science and Engineering, Guilin University of Technology , Guilin, Guangxi 541004, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332-0340, United States.
authors.forename: Yuanzhi
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Department of Geoscience, University of Wisconsin-Madison , 1215 W. Dayton Street, Madison, Wisconsin 53706, United States.
authors.forename: Eric
authors.initials: E
authors.lastname: Roden
authors.affiliation: Department of Civil and Environmental Engineering, University of Nevada , Reno, Nevada 89557, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
mesh_terms: D002606:Charcoal / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D004777:Environment; D005290:Ferric Compounds / Q000378:metabolism*; D007501:Iron / Q000737:chemistry; D010084:Oxidation-Reduction; D020592:Shewanella / Q000378:metabolism*; D012995:Solubility; D013696:Temperature
chemical_list: D005290:Ferric Compounds; C540010:biochar; D002606:Charcoal; C000499:ferric oxide; D007501:Iron