白洋淀典型淀区沉积物间隙水溶解性有机物的光谱时空演变特征

Temporal and Spatial Evolution Characteristics of DOM Spectra in Sediment Interstitial Water in Typical Zones of Baiyangdian Lake

使用紫外-可见光谱(UV-vis)和三维荧光光谱-平行因子分析法(EEM-PARAFAC),分析了白洋淀2019年春季、夏季和秋季沉积物间隙水中溶解性有机物(DOM)的来源及分布特征.结果表明,白洋淀夏季沉积物间隙水DOM的相对浓度显著高于春秋季;E2/E3值显示夏季的间隙水DOM分子量要高于春秋季.使用EEM-PARAFAC从间隙水中提取了3种类蛋白组分(C1、C2、C3)和2种类腐殖质组分(C4、C5);类蛋白是DOM的主要构成组分,占比达到(63.56±16.07)%.DOM总荧光强度、各组分荧光强度及其相对丰度季节差异不显著,空间差异显著;养殖区的类蛋白物质占主体,自然区的类腐殖质物质占主体.沉积物间隙水的高BIX、FI、β∶α以及低HIX,表明沉积物间隙水DOM具有低腐殖化,强自生源特征.与此同时,环境因子与荧光组分的回归分析可以为管理者预测沉积物间隙水水质提供支持.

The sources and distribution of dissolved organic matter(DOM) in the interstitial water of Baiyangdian Lake sediments were analyzed using the ultraviolet-visible absorption spectrum(UV-vis) method and three-dimensional excitation emission matrix fluorescence spectroscopy-parallel factor analysis(EEM-PARAFAC).Results showed that the DOM concentrations and molecular weight were significantly higher in summer than in spring and autumn,based on a254 and E2/E3 values.Three protein-like substance(C1,C2,and C3) and two humic-like substances(C4,C5) were identified with the PARAFAC model.Moreover,protein-like substances accounted for the majority of DOM,reaching(63.56 ± 16.07) %.Total DOM fluorescence intensity,the fluorescence intensity of each component,and the relative abundance exhibited significant spatial variation among the different functional zones in Baiyangdian Lake.Protein-like substances were mainly found in the breeding area,whereas humic-like substances mainly occurred in the natural area.The high BIX,FI,β∶ α,and low HIX indicated that DOM in sediment interstitial water exhibited low humification and highly autochthonous characteristics.Moreover,the perfect regression equations between water quality and the fluorescent components could provide a useful reference for managers aiming to protect the ecosystem of Baiyangdian Lake.