两江交汇处水体溶解性有机质的吸收和荧光光谱特征:以渠江-嘉陵江、涪江-嘉陵江为例

利用三维荧光和紫外-可见吸收光谱手段,分析了渠江、涪江和嘉陵江交汇处水体DOM特征变化.结果表明,干支流各采样点水体DOM的FI值1.4,HIX值0.8,表现出明显陆源输入特征,整个研究区域水体混合模式为非保守混合,对交汇处水体DOM地化特征变化有一定贡献,但并非主导因素.河流沿岸不同土地利用类型对交汇处水体DOM特征改变有明显影响,聚类分析发现,所有采样点可分为两大类,一类为沿岸以森林和农田生态系统为主(渠江-嘉陵江交汇处),另一类为沿岸以城市用地为主(涪江-嘉陵江交汇处),前者向干流水体中输入芳香化程度和腐殖化程度较高的DOM,后者以浓度较高而结构相对较简单的DOM输入为主.此外,涪江-嘉陵江交汇处类蛋白质荧光组分信号增强,出现荧光T峰,表明人为活动对水体质量的影响明显.

Characteristics of Absorption and Fluorescence Spectra of Dissolved Organic Matter from Confluence of Rivers: Case Study of Qujiang River-Jialing River and Fujiang River-Jialing River

Three-dimensional fluorescence spectroscopy combined with ultraviolet-visible(UV-Vis) absorption spectra was used to investigate the change characteristics of dissolved organic matter(DOM) in confluences water of Qujiang River-Jialing River and Fujiang River-Jialing River, respectively. The results suggested that DOM showed a significant terrestrial input signal in all the sampling sites, FI<1.4, HIX>0.8, possibly representing remarkable signals of humus resulted from humic-like component. Moreover, the mixing zone of this study showed a non-conservative mixed behavior, which had a limited contribution, and was not the dominant factor to interpret the change characteristics of DOM in confluences zones. Different land-use types along all the rivers had an obvious impact on DOM inputs. Results of cluster analysis showed that a higher degree of aromaticity and humification components was observed as the predominant contributor to DOM when the land-use type was forest and farmland ecosystem, for example the confluences of Qujiang River-Jialing River. On the other hand, high concentrations of DOM with relative simple structures were found in the water when the urban land-use type was predominant, for example the confluences of Fujiang River-Jialing River. Meanwhile, a new fluorescent signal of protein-like components(peak T) appeared, which manifested a significant effect on the water quality resulted from anthropogenic activities.