Yiran Liu , Weijun Zhao , Peng Zhang , Qing-long Fu , Chenglong Yu , Songhu Yuan
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引用次数: 0
Abstract
The electron gain and loss of natural organic matter (NOM) plays an important role in the biogeochemical cycling of element and contaminant attenuation. The electron-donating capacity (EDC) and electron-accepting capacity (EAC) of NOM determine its electron exchange ability. However, the influences of bonded matrices on EDC and EAC of NOM remain unclear. Here we investigated the variations in EDC and EAC of NOM during its interaction with Fe oxyhydroxides. Compared to original NOM, the presence of Fe oxyhydroxides slightly decreased the EDC of dissolved NOM by 0.58–2.08 mmol e−/g C and of adsorbed NOM by 0.33–2.67 mmol e−/g C. However, the EAC of dissolved NOM and adsorbed NOM significantly (p < 0.05) increased by 1.92–14.17 and 3.08–36.67 mmol e−/g C, respectively. The excessive increase of EAC was mainly attributed to changes in NOM chemical components, particularly increases in oxidative components such as Fe(III) and quinonoid carbonyls, rather than changes in EDC. For dissolved NOM, the heightened EAC was mainly attributed to the complexation of Fe(III) by carboxyl in NOM. For adsorbed NOM, the boosted EAC was predominantly linked to the enrichment of quinonoid carbonyl through the selective molecular fractionation and the oxidative polymerization of polyphenols in NOM. Our finding highlights the previously overlooked phenomenon of asymmetrical changes of EDC and EAC of NOM during its interaction with Fe oxyhydroxides. The increased EAC could potentially affect various biogeochemical processes, such as methane production, anaerobic ammonium oxidation and microbial Fe(III) reduction.
天然有机物(NOM)的电子增益和损耗在元素和污染物衰减的生物地球化学循环中发挥着重要作用。NOM 的电子供能(EDC)和电子受能(EAC)决定了其电子交换能力。然而,粘结基质对 NOM 的 EDC 和 EAC 的影响仍不清楚。在此,我们研究了 NOM 与氢氧化铁相互作用过程中 EDC 和 EAC 的变化。与原始 NOM 相比,羟基铁的存在使溶解 NOM 的 EDC 稍微降低了 0.58-2.08 mmol e-/g C,使吸附 NOM 的 EDC 降低了 0.33-2.67 mmol e-/g C;然而,溶解 NOM 和吸附 NOM 的 EAC 显著增加(p < 0.05),分别增加了 1.92-14.17 和 3.08-36.67 mmol e-/g C。EAC 的过度增加主要归因于 NOM 化学成分的变化,特别是铁(III)和醌类羰基等氧化成分的增加,而不是 EDC 的变化。对于溶解的 NOM,EAC 的增加主要是由于 NOM 中的羧基络合了铁(III)。对于吸附的 NOM,EAC 的增加主要与 NOM 中多酚的选择性分子分馏和氧化聚合富集醌羰基有关。我们的发现凸显了以前被忽视的现象,即在与铁氧氢氧化物相互作用的过程中,NOM 的 EDC 和 EAC 发生了不对称变化。增加的 EAC 可能会影响各种生物地球化学过程,如甲烷生产、厌氧氨氧化和微生物铁(III)还原。
期刊介绍:
Chemical Geology is an international journal that publishes original research papers on isotopic and elemental geochemistry, geochronology and cosmochemistry.
The Journal focuses on chemical processes in igneous, metamorphic, and sedimentary petrology, low- and high-temperature aqueous solutions, biogeochemistry, the environment and cosmochemistry.
Papers that are field, experimentally, or computationally based are appropriate if they are of broad international interest. The Journal generally does not publish papers that are primarily of regional or local interest, or which are primarily focused on remediation and applied geochemistry.
The Journal also welcomes innovative papers dealing with significant analytical advances that are of wide interest in the community and extend significantly beyond the scope of what would be included in the methods section of a standard research paper.