微生物降解影响下湖泊草源DOM与重金属的相互作用

通过微生物降解实验以及荧光滴定法研究草源溶解性有机质（DOM）光谱特性的不同以及铜（Cu）与草源DOM在微生物降解影响下的相互作用.三维荧光光谱结合PARAFAC分析显示，草源DOM含有3个荧光组分，新鲜的草源DOM以类蛋白质组分C2为主，微生物降解之后类腐殖质组分C1和C3成为草源DOM中的主要物质.二维相关光谱（2D-COS），表明类蛋白物质在微生物降解过程中比类腐殖物质有着更高的敏感度和更快降解速率.并且随着Cu的增加，草源DOM中所有组分的荧光强度在微生物降解前后均发生明显猝灭.草源DOM原始样品中类腐殖质组分的络合常数大于类蛋白质组分，说明相比于类蛋白质组分，原始草源DOM中的类腐殖质组分有着更高的金属结合能力.而类蛋白质组分的络合常数在微生物降解之后的草源DOM中却高于类腐殖质组分.微生物降解对草源DOM的光谱特性以及金属结合能力有着显著影响，并对湖泊中重金属的生物有效性以及生态风险有着重要的意义.

The interaction between macrophytes-derived dissolved organic matter and heavy metal under the influence of microbial degradation

Fluorescence properties of the macrophytes-derived dissolved organic matter (DOM) and the interaction between Cu-binding and macrophytes-derived DOM under the influence of microbial degradation were studied by microbial degradation experiments and fluorescence titrimetric method. Three-dimensional fluorescence spectra combined with PARAFAC analysis showed that macrophytes-derived DOM contained three fluorescence components, i.e., humus-like components C1, C3, and protein-like components C2, and it was dominated by protein- and humus-like components before and after microbial degradation, respectively. 2D correlation spectra (2D-COS) showed that the protein-like substances were more sensitive and had faster degradation rate in the process of microbial degradation compared with the humus-like materials. Meanwhile, with the increasing concentration of Cu²⁺, the intensity of all fluorescence components was significantly quenched before and after microbial degradation. Compared with the protein-like components, the logKa values of humus-like components of macrophytes-derived DOM before microbial degradation was significantly larger, indicating that humus-like components had a higher metal-binding capacity than protein-like components. However, the logKa values of humus-like components in DOM were smaller than that of protein-like components after microbial degradation. Microbial degradation has a significant impact on the spectral properties and metal-binding capacity of macrophytes-derived DOM, which is meaningful to the bioavailability and ecological risks of heavy metals in lakes.