Biochar-derived dissolved organic matter (DOM) is important for determining the application potential of biochar in soil remediation. However, little is known about the degradation behavior of biochar-derived DOM and its interaction with heavy metals. Here, incubation experiments combined with quenching titration experiments, which analyzed by spectroscopic technology and chemometric method, were conducted to reveal such behaviors and mechanisms. Ultraviolet–visible (UV–Vis) spectra showed that high aromatic and hydrophobic fractions were enriched in biochar-derived DOM and enhanced during the cultivation process, thus the biochar-derived DOM may retain a high aromaticity, stability, and resistance. However, the environmental risk of Cu caused by the increase of DOM hydrophobicity cannot be overlooked while applying biochar to polluted soil. One fulvic-like (C1), one protein-like (C2) and two humic-like (C3, C4) substances were identified from biochar-derived DOM by using parallel factor analysis of excitation-emission matrix. Additionally, the fluorescence intensity variations of these components in DOM offered an additional interpretation for the observations from UV–Vis spectra. Two-dimensional correlation spectroscopy revealed that Cd binding to biochar-derived DOM first occurred in the protein- and fulvic-like fraction while protein- and humic-like substances had a stronger affinity for Cu. Furthermore, both phenolic and carboxyl groups firstly participated in the binding process of Cd with biochar-derived DOM, while polysaccharide gave the fastest response to Cu binding. These results clearly demonstrated the differences in specific heavy metal binding features of individual fluorescent substances and functional groups in biochar-derived DOM and contribute to improving the application effect of biochar in a multi-heavy metal polluted soil system.

生物炭来源的溶解有机物（DOM）对于确定生物炭在土壤修复中的应用潜力非常重要。但是，关于生物炭来源的DOM的降解行为及其与重金属的相互作用知之甚少。在这里，进行了孵化实验和淬灭滴定实验的结合，并通过光谱技术和化学计量学方法进行了分析，以揭示这种行为和机理。紫外-可见（UV-Vis）光谱表明，高芳香族和疏水级分富含生物炭来源的DOM，并在培养过程中得到增强，因此生物炭来源的DOM可以保留较高的芳香性，稳定性和抗性。然而，在污染土壤上施用生物炭时，不能忽视由DOM疏水性增加引起的Cu的环境风险。通过使用激发-发射矩阵的并行因子分析，从生物炭衍生的DOM中鉴定出一种黄腐病毒样（C1），一种蛋白质样蛋白（C2）和两种腐殖质样（C3，C4）物质。此外，DOM中这些成分的荧光强度变化为从UV-Vis光谱中观察到的现象提供了额外的解释。二维相关光谱显示，Cd与生物炭来源的DOM的结合首先发生在蛋白质和黄腐病毒样部分中，而蛋白质和腐殖质样物质对Cu具有更强的亲和力。此外，酚基和羧基都首先参与了Cd与生物炭衍生的DOM的结合过程，而多糖对Cu结合的响应最快。