不同来源溶解有机质与镉和锑的相互作用

运用紫外-可见吸收光谱和三维荧光光谱结合平行因子分析的荧光淬灭技术,研究了植物、土壤、沉积物和水体4种来源DOM及其不同组分与Cd和Sb的相互作用.结果表明,随着Cd浓度的升高,4种来源DOM的光谱斜率(S275~295)和光谱斜率比(SR)都出现了明显下降,而DOM与Sb反应后其SR和S275~295值变化不明显,说明2种金属与DOM的结合机制有所不同,Cd与DOM的结合促使小分子DOM向大分子转化,而DOM与Sb结合后没有出现分子量的明显增大.对于相同金属处理,不同来源DOM及DOM不同组分荧光强度的变化不同,说明不同来源DOM与Cd和Sb结合的活性组分不同,且不同组分对Cd和Sb的络合能力差异较大.另外,在Cd处理中,Ex/Em= 301nm /346nm处的类蛋白组分的荧光强度变化有所波动,说明与类腐殖质组分相比,某些类蛋白组分与Cd形成的络合物稳定性较差.

Interaction of cadmium and stibium with dissolved organic matter from different sources

The interaction of DOM from four sources(plant,soil,sediment,and water) with two kinds of metal(Cd and Sb) was investigated by UV-Visible absorbance spectroscopy and fluorescence quenching titrations combined with excitation-emission matrix(EEM) spectra and parallel factor analysis(PARAFAC).Spectral slope(S275~295) and spectral slope ratio(SR) of DOM from four sources decreased obviously with increasing Cd concentration;however,no obvious changes were observed in DOM-Sb binding.It indicated that binding mechanisms of DOM and the two kinds of metal were different.The DOM-Cd binding made DOM transform from the small molecules into macromolecules,while DOM-Sb binding didn’t change molecular weight of DOM.In treatments with the same metal addition,fluorescence intensity of DOM components from different sources varied significantly.It suggested that DOM from different sources had different active components when binding with metal,and the active components showed different binding properties.In addition,larger fluctuations in the quenching curves of protein-like component(Ex/Em= 301nm/346nm) were observed in presence of Cd,suggesting that the complexation stability of some protein-like substances was weaker compared to that of humic-like ones.