沼气发酵残留物中DOM的结构特征及其对重金属的影响机制

Dissolved organic matter (DOM) obtains many functional groups. Due to the presence of these functional groups, DOM presents a variety of activity, of which the most important is the complexation with metal ions. However, the structural characteristics of DOM from biogas residues and its mechanism on the complexation with heavy metals have rarely been studied. In this work, the components and structure of DOM will be characterized by spectroscopic techniques, gas chromatograph spectrometer, etc. The binding capacities of DOM with heavy metals will be studied using fluorescence quenching titration, revealing the migration, transformation and bioavailability of heavy metals. Infrared spectroscopy, X-ray energy dispersive spectroscopy and scanning electron microscopy analysis will be used to analyze the structural changes and surface characteristics of complexes and explain the mechanism of DOM with heavy metals. Furthermore, the application of two-dimensional correlation spectroscopy can provide more information on metal binding sites as well as complexation mechanism. This research results can provide a scientific basis for the migration and transformation of heavy metals and the remediation of contaminated soils, which has important guiding significance for the ecological environment impact assessment of biogas construction.

溶解性有机质(DOM)中含有多种功能基团。由于这些功能基团的存在，DOM在环境中表现出多种活性，其中最重要是DOM与金属离子的络合作用。目前，在沼气发酵残留物中DOM对重金属相互作用的研究相对薄弱。本项目从不同沼气发酵残留物中DOM的组分和结构特性出发，利用光谱学分析技术和GC等分析仪器，表征沼气发酵残留物DOM的结构特性；从DOM对重金属络合作用的角度出发，利用荧光猝灭滴定技术定量表征DOM与重金属的络合能力，揭示DOM对重金属迁移转化及生物可利用性的影响；利用红外光谱、X射线能谱仪和扫描电镜等分析DOM络合物的结构变化和表面特征，揭示DOM与重金属作用机理；同时利用二维相关光谱技术分析紫外和红外光谱，探索不同沼气发酵残留物DOM与重金属络合点的变化和配位机理。本研究可为受污染土壤施用发酵残留物后重金属的迁移规律和污染治理提供科学依据，为沼气工程建设的生态环境影响评价具有重要指导意义。

本项目主要研究沼气发酵残留物DOM的组分及结构特性和不同原料沼气发酵残留物DOM与重金属络合实验及络合机制。研究结果表明，不同原料厌氧发酵沼液DOM在荧光峰组分上没有明显的区别；发酵残留物DOM与重金属络合的对数稳定常数较高，络合物相对较稳定，尤其是Fe离子；二维相关光谱分析能够揭示发酵残留物DOM各荧光组分与金属离子结合的先后顺序。这些研究结果能够反映发酵残留物DOM与重金属的络合机制，从而为沼肥施用后土壤中金属离子的形态分布、迁移转化过程的影响提供科学指导，也能够为重金属污染土壤的修复提供理论支持。