腐殖质成分对微生物介导的铁氧化还原过程和羟基自由基产生的多重影响,Environmental Science & Technology

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腐殖质成分对微生物介导的铁氧化还原过程和羟基自由基产生的多重影响
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2022-10-12 , DOI: 10.1021/acs.est.2c03799
Ruixia Han _{1,

2,

3} , Zhe Wang _{1,

3} , Jitao Lv ₄ , Zhe Zhu _{1,

3,

5} , Guang-Hui Yu ₆ , Gang Li _{1,

3} , Yong-Guan Zhu _{1,

3,

4}

Affiliation

微生物介导的铁氧化还原过程在元素的生物地球化学循环中具有重要意义，元素通常与环境中的土壤有机质 (SOM) 相结合。尽管 SOM 组分对单个还原或氧化过程的影响已得到广泛研究，但仍缺乏全面的了解。在这里，我们使用水铁矿Shewanella oneidensis MR-1 和操作定义的 SOM 成分，包括从黑土和泥炭中提取的黄腐酸 (FA)、腐殖酸 (HA) 和腐殖质 (HM)，探索了 SOM 介导的微生物铁还原和羟基自由基 ( ^•OH) 生产过程。结果表明，SOM 的添加抑制了水铁矿向高结晶氧化铁的转变。尽管 FA 和 HA 由于络合作用和高电子交换能力使 Fe(II) 产量平均增加了四倍以上，但 HA 抑制了 30-43% 的^• OH 产量，而 FA 对其没有显着影响。超氧化物(O ₂^{•– ) 是含FA 系统中}^• OH 生产的主要中间体，而单电子和双电子转移过程在含HA 和HM 的系统中同时发生。^{这些发现提供了对 SOM 在调节微生物介导的铁氧化还原过程和•} OH 产生方面的多种机制的深刻见解。

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Multiple Effects of Humic Components on Microbially Mediated Iron Redox Processes and Production of Hydroxyl Radicals

Microbially mediated iron redox processes are of great significance in the biogeochemical cycles of elements, which are often coupled with soil organic matter (SOM) in the environment. Although the influences of SOM fractions on individual reduction or oxidation processes have been studied extensively, a comprehensive understanding is still lacking. Here, using ferrihydrite, Shewanella oneidensis MR-1, and operationally defined SOM components including fulvic acid (FA), humic acid (HA), and humin (HM) extracted from black soil and peat, we explored the SOM-mediated microbial iron reduction and hydroxyl radical (^•OH) production processes. The results showed that the addition of SOM inhibited the transformation of ferrihydrite to highly crystalline iron oxides. Although FA and HA increased Fe(II) production over four times on average due to complexation and their high electron exchange capacities, HA inhibited 30–43% of the ^•OH yield, while FA had no significant influence on it. Superoxide (O₂^•–) was the predominant intermediate in ^•OH production in the FA-containing system, while one- and two-electron transfer processes were concurrent in HA- and HM-containing systems. These findings provide deep insights into the multiple mechanisms of SOM in regulating microbially mediated iron redox processes and ^•OH production.

更新日期：2022-10-12

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