Zhu Sihua, Yang Peijie, Tian Peili, Zhang Siqi, Tian Shanyi, Yin Yongguang, Lv Jitao, Yang Caiyun, Zhou Zhongbo, Tang Zhenwu, Wang Dingyong, Jiang Tao
Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China.
Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Water Res. 2025 Jul 29;287(Pt A):124316. doi: 10.1016/j.watres.2025.124316.
The electron-donating capacity (EDC) of dissolved organic matter (DOM) plays a central role in regulating environmental redox processes, and is closely governed by the DOM characteristics. As DOM increasingly becomes a focal point in carbon sequestration strategies aimed at mitigating climate change, understanding how its molecular characteristics influence redox functionality is critical. However, the role of DOM chemodiversity, including molecular diversity, functional diversity, and compositional traits, in governing its EDC remains underexplored at the molecular scale. In this study, representative allochthonous, autochthonous, and mixed DOM samples were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), UV-Vis spectroscopy, and excitation-emission matrix fluorescence spectroscopy. The EDC was quantified using a decolorization assay based on ABTS reduction. Results showed that EDC was not significantly correlated with overall molecular diversity, but was strongly associated with the relative abundance of polyphenolic, highly aromatic, and unsaturated compounds. These molecules also exhibited greater persistence and formed highly interconnected and thermodynamically constrained transformation networks, indicating a structural trade-off between redox functionality and degradability. This structure-function-persistence relationship implies that changes in DOM stability during carbon sequestration may significantly influence its redox capacity, thereby modulating key environmental processes such as metal cycling, and contaminant fate. By elucidating the molecular-level linkages between DOM chemical traits and electron-donating activity, this study reveals how structural characteristics govern redox functionality, emphasizes the dominant role of composition over diversity in regulating DOM reactivity, and highlights potential ecological risks relevant to carbon stabilization strategies.
溶解有机物（DOM）的供电子能力（EDC）在调节环境氧化还原过程中起着核心作用，并且受到DOM特性的密切影响。随着DOM越来越成为旨在缓解气候变化的碳固存策略的焦点，了解其分子特性如何影响氧化还原功能至关重要。然而，在分子尺度上，DOM化学多样性（包括分子多样性、功能多样性和组成特征）在控制其EDC方面的作用仍未得到充分探索。在本研究中，使用傅里叶变换离子回旋共振质谱（FT-ICR MS）、紫外可见光谱和激发发射矩阵荧光光谱对代表性的外源、内源和混合DOM样品进行了分析。通过基于ABTS还原的脱色测定法定量了EDC。结果表明，EDC与整体分子多样性没有显著相关性，但与多酚类、高芳香性和不饱和化合物的相对丰度密切相关。这些分子还表现出更高的持久性，并形成了高度相互连接且受热力学限制的转化网络，表明在氧化还原功能和可降解性之间存在结构权衡。这种结构-功能-持久性关系意味着碳固存过程中DOM稳定性的变化可能会显著影响其氧化还原能力，从而调节金属循环和污染物归宿等关键环境过程。通过阐明DOM化学特征与供电子活性之间的分子水平联系，本研究揭示了结构特征如何控制氧化还原功能，强调了组成在调节DOM反应性方面相对于多样性的主导作用，并突出了与碳稳定策略相关的潜在生态风险。
