Xu S, Adhikari D, Huang R, Zhang H, Tang Y, Roden E, Yang Y. Biochar-Facilitated Microbial Reduction of Hematite.
ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016;
50:2389-2395. [PMID:
26836650 DOI:
10.1021/acs.est.5b05517]
[Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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.
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