浑太水系水体中不同粒径有机胶体荧光光谱特性

将超滤系统与孔径(相对分子质量)为100×103和1×103超滤膜结合,对浑太水体中总溶解有机质(DOM)进行分级,并运用三维荧光光谱技术对不同级有机质的荧光光谱特性进行了对比分析.结果表明,浑太水系水体的荧光图谱表现为紫外光区类腐殖质、可见光区类腐殖质、类色氨酸(短波和长波激发峰)4个荧光峰,其中,类腐殖质荧光物质主要赋存于胶体形态(相对分子质量<100×103)和真溶解态(相对分子质量<1×103)中,由于类蛋白物质与水体中胶体的相互作用,使得胶态类蛋白荧光物质也占有相当大的比例.峰、枯两水期相比,丰水期由于陆源汇流的冲击作用,阻止了胶体颗粒的凝聚,使DOM中小胶态和真溶解态有机质所占的质量分数较高.通过比较不同粒径有机质的荧光指数、生物源指数、腐殖化指数以及DOM与荧光强度的相关性分析可以得出,真溶解态中腐殖质主要源自于内源作用,而胶态腐殖质具有陆源特征,新产生的有机质在真溶解态中占有更大的比例,水体中类腐殖质是溶解有机碳(DOC)的主要来源,但由于浑太水系各采样断面存在不同程度的污染,类蛋白物质对DOC的贡献也不能忽略.

Fluorescence Characteristics of Fractionated Colloidal Organic Matter in Freshwater from Hunhe and Taizihe Watersheds

The ultrafiltration system with molecular mass of 100×10³ and 1×10³ membrane was used for the fractionation of total dissolved organic matter (DOM) in waters from Hunhe and Taizihe Watersheds. The fluorescence properties of colloidal organic matter with different sizes were investigated using a three-dimension excitation-emission matrix (3-D EEM) fluorescence spectroscopy. It was shown that the tryptophan-, fuvic-and humic-like materials were presented in the waters from Hunhe and Taizihe Watersheds, of which fuvic-and humic-like materials were mainly in colloidal form with small size (relative molecular mass<100×10³) and truly dissolved phase (relative molecular mass<1×10³). The adsorption of protein-like matters onto the colloid particles made the majority of these materials in colloidal phase though they had a low molecular mass. The higher percentages of small colloidal and truly dissolved organic carbon in total dissolved organic carbon (DOC)were observed in the water samples collected in wet season. Fluorescence index (FI), index of recent autochthonous contribution (BIX) and humification index (HIX) indicated that humic-like components in truly dissolved phase were mainly originated from autochthonous source and colloidal humic-like components were mainly derived from terrestrial organic matter. The recent autochthonous organic matter made a major contribution to truly dissolved phase. The humic-like matter was the domain of DOC content, but the contribution of protein-like materials to the organic carbon was not negligible due to the pollution of waterbody by industrial wastewater discharge.