The binding of Cd and Cu to dissolved organic matter (DOM) derived from compost (CP) and rice straw (ST) was studied through an approach combining parallel factor (PARAFAC) analysis and two-dimensional correlation spectroscopy (2DCOS). Both humic-like and protein-like substances have been observed in CP and ST. Comparing with the Cu, Cd exhibited a lower affinity to DOM, and the quenching curve of Cd failed to be fitted by the Ryan and Weber Model, indicating that the environmental risk caused by applying CP or ST to Cd-polluted soil should be considered. The stability constants (log K_M) of Cu ranged from 3.87 to 5.03, and a larger value was found in CP than those in ST. Protein-like component also showed obvious fluorescence quenching with heavy metals addition. Besides, in CP, phenol-OH and carboxyl showed the fastest response to Cd and Cu, respectively; however, in ST, amide group and phenol-OH displayed the fastest response to Cd and Cu, respectively. These results provide a more detailed knowledge of the interaction mechanism of heavy metals with DOM at the molecular level, which is of great significance for reasonable application of compost and rice straw and efficient control of heavy metal in farmland soil.

中文翻译：

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EEM-PARAFAC结合二维FTIR相关分析研究镉和铜与堆肥和稻草衍生的DOM的结合特性

通过结合平行因子（PARAFAC）分析和二维相关光谱法（2DCOS）的方法，研究了镉和铜与堆肥（CP）和稻草（ST）产生的可溶性有机物（DOM）的结合。在CP和ST中都观察到了腐殖质和蛋白质样物质。与Cu相比，Cd对DOM的亲和力较低，Ryan和Weber模型未能拟合Cd的猝灭曲线，这表明应考虑将CP或ST应用于Cd污染土壤所引起的环境风险。稳定常数（log  K _M的Cu）在3.87至5.03的范围内，并且在CP中发现的值大于在ST中的值。蛋白质样成分还显示出明显的荧光猝灭，并添加了重金属。此外，在CP中，苯酚-OH和羧基对Cd和Cu的响应最快。然而，在ST中，酰胺基和苯酚-OH分别显示出对Cd和Cu的最快响应。这些结果为在分子水平上重金属与DOM的相互作用机理提供了更详细的知识，对于合理使用堆肥和稻草并有效控制农田土壤中的重金属具有重要意义。