Department of Civil and Environmental Engineering, University of Nevada , Reno, Nevada 89557, United States.
School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332-0340, United States.
Environ Sci Technol. 2016 Mar 1;50(5):2389-95. doi: 10.1021/acs.est.5b05517. Epub 2016 Feb 18.
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.
作为土壤有机质（SOM）的重要组成部分，热解碳的转化在碳和其他氧化还原活性元素（如铁（Fe））的生物地球化学循环中起着关键作用。在此，我们研究了小麦秸秆衍生生物炭对异化金属还原菌希瓦氏菌（Shewanella oneidensis MR-1）在缺氧条件下还原 100mM 赤铁矿的影响。在 10mg/L 生物炭存在下，赤铁矿的长期微生物还原程度和初始还原速率提高了 2 倍以上。10mg/L 生物炭的可溶浸出液也可促进 Fe(III)还原，其程度与生物炭浸出液的表观电子穿梭能力相当。微生物预还原生物炭浸出液可促进赤铁矿的非生物还原，这与生物炭浸出液中半醌功能基团的电子穿梭能力一致。电子顺磁共振（EPR）分析表明，生物炭浸出液相关的半醌官能团可能参与了氧化还原反应。除了电子穿梭效应外，生物炭颗粒还吸附了 0.5-1.5mM 的生物成因 Fe(II)，从而使赤铁矿的长期还原程度提高了 1.4-1.7 倍。我们的研究结果表明，在含有较高含量本地产热解碳或大量生物炭应用的土壤中，Fe 氧化还原循环可能会受到热解碳的强烈影响。
