Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science , Swiss Federal Institute of Technology (ETH) , 8092 Zurich , Switzerland.
Environ Sci Technol. 2018 May 1;52(9):5236-5245. doi: 10.1021/acs.est.8b00594. Epub 2018 Apr 10.
Electron-donating phenolic and electron-accepting quinone moieties in peat dissolved organic matter (DOM) are considered to play key roles in processes defining carbon cycling in northern peatlands. This work advances a flow-injection analysis system coupled to chronoamperometric detection to allow for the simultaneous and highly sensitive determination of these moieties in dilute DOM samples. Analysis of anoxic pore water and oxic pool water samples collected across an ombrotrophic bog in Sweden demonstrated the presence of both phenolic and quinone moieties in peat DOM. The pore water DOM had higher quantities of phenolic but not quinone moieties compared with commonly used model aquatic and terrestrial DOM isolates. Significantly lower phenol content in DOM from oxic pools than DOM from anoxic pore waters indicated oxidative DOM processing in the pools. Consistently, treatment of peat DOM with laccase, a phenol-oxidase, under oxic conditions resulted in an irreversible removal of phenols and reversible oxidation of hydroquinones to quinones. Electron transfer to peat DOM was fully reversible over an electrochemical reduction and subsequent O-reoxidation cycle, supporting that quinones in peat DOM serve as regenerable microbial electron acceptors in peatlands. The results advance our understanding of redox processes involving phenolic and quinone DOM moieties and their roles in northern peatland carbon cycling.
在泥炭中，电子给体酚类和电子受体醌类部分被认为在决定北方泥炭地碳循环的过程中起着关键作用。本工作提出了一种流动注射分析系统，与计时安培检测相结合，允许同时对稀 DOM 样品中的这些部分进行高灵敏度测定。对从瑞典一个富养沼泽中采集的缺氧孔隙水和有氧池水样的分析表明，泥炭 DOM 中存在酚类和醌类部分。与常用的模型水生和陆地 DOM 分离物相比，孔隙水 DOM 中含有更多的酚类部分，但不含醌类部分。与缺氧孔隙水 DOM 相比，含氧池 DOM 中的苯酚含量明显较低，表明在池中有 DOM 的氧化过程。同样，在有氧条件下用漆酶（一种酚氧化酶）处理泥炭 DOM 会导致不可逆地去除苯酚和可逆地氧化对苯二酚到醌。在电化学还原和随后的 O 再氧化循环过程中，向泥炭 DOM 的电子转移是完全可逆的，这支持了泥炭 DOM 中的醌类作为泥炭地中可再生微生物电子受体的作用。这些结果推进了我们对涉及酚类和醌类 DOM 部分的氧化还原过程及其在北方泥炭地碳循环中的作用的理解。
