Variation characteristics and source analysis of dissolved organic matter along the river into Baiyangdian Lake

The spectral characteristics of chromophoric dissolved organic matter (CDOM) in three inflow rivers of Baiyangdian Lake (Fu River, Xiaoyi River and Baigouyin River) were analyzed by UV-vis absorption spectroscopy, three-dimensional fluorescence spectroscopy, parallel factor analysis and principal component analysis, and the composition, sources and the influence mechanism of CDOM on water quality were explained. The results showed that the order of CDOM average concentration was Fu River>Xiaoyi River>Baigouyin River. The aromaticity and molecular weight of CDOM in the Fu River were higher than those in other rivers, the degree of humification in the Baigouyin River was higher than those in other rivers, and the proportion of endogenous substances in CDOM in the Xiaoyi River was higher than those in other rivers. Humic-like components C1, C2, C3 and protein-like components C4 were detected in the three rivers, among which C1, C2 and C3 were similar in origin and different from C4. The variation of maximum fluorescence intensity and total fluorescence intensity of each component in the three rivers showed that CDOM of the Fu River was from point and non-point mixed sources, CDOM of the Xiaoyi River was mainly from point sources, and CDOM of the Baigouyin River diversion was contained by the water source itself.