夏季渭河西安段溶解性有机质(DOM)的特征、分布及来源分析

通过紫外吸收光谱,三维荧光光谱结合平行因子分析(EEMs-PARAFAC)方法及主成分分析(PCA),研究了夏季渭河西安段水体中的溶解性有机质(DOM)的组成、来源,及其与水质指标的相关性.在研究区域共检出2种类别5个不同的DOM组分,分别为类腐殖质荧光组分C1、C2、C3、C5和1个类蛋白类荧光组分C4,5个组分具有同源性.对比分析光谱斜率S、SUVA₂₅₄、α355和DOC浓度,上游(S1—S5)和下游(S13—S17)各组分分子量和腐殖化程度接近但来源有所差异,中游(S6—S12、S18—S19)分子量和腐殖化程度最低;研究区域DOM和CDOM浓度值变化基本保持一致.通过三维光谱参数和主成分分析进行DOM源解析,内源贡献率为72.36%,外源贡献率为12.45%,累计方差贡献率为84.81%;污废水排放是组分C1、C4的主要来源,C2、C3、C5则来源于城市景观水体和湿地公园中微生物和浮游动植物的活动产生,TN与外源具有较好的相关性而TP与内源相关性较高.水质指标DO、DOC、COD、TN、TP与DOM组分有较强的相关性.在此基础上建立了多元线性回归方程,一定程度上能够利用荧光组分组成和特征反映渭河夏季的水质状况.

Characteristics,distribution and source analysis of dissolved organic matter in Xi'an section of Weihe River in summer

By using ultraviolet spectrophotometry,three-dimensional fluorescence spectrum combined with parallel factor analysis(EEMs-PARAFAC)and principal component analysis(PCA),the composition,source of dissolved organic matter(DOM)and its correlation with other water quality indexes of Xi'an section of Weihe River in summer were studied.The results showed that five different components in two categories were detected,including four humus-like fluorescence components C1,C2,C3,C5 and one protein-like fluorescence component C4.And there were a high homology for the five components.By analyzing the spectral slope S,SUVA₂₅₄,α355 and DOC concentration,it showed that the molecular weight and humification degree of DOM components in the upper and lower reaches were similar,but the sources were different.While the molecular weight and humification degree in the middle reaches were the lowest.The DOM and CDOM concentration in the study region were basically consistent.The source apportionment through three-dimensional spectral parameters and principal component analysis indicated that the endogenous contribution of DOM was 72.36%,while the exogenous contribution was 12.45%and the cumulative variance contribution was 84.81%.The sewage discharge contributed to the source of components C1 and C4 mainly,while source of components C2,C3 and C5 were attributed to the activities of microorganisms,planktons and plants in urban landscape water bodies and wetland parks.The total nitrogen had a good correlation with exogenous sources while TP correlated with endogenous sources highly.The linear multiple regression equations founded can reflect the water quality of Weihe River in summer to a certain extent.