Fluorescence characteristics of DOM and its influence on water quality of rivers and lakes in the Dianchi Lake basin

Dissolved organic matter (DOM) is an important part of the material cycle in the water environment, and it plays an important role in the nutrient cycle of nitrogen and phosphorus in eutrophic water and biological processes. Dianchi Lake is a heavily eutrophic plateau lake in China. To investigate the fluorescence characteristics of DOM and the influences of DOM on water quality of rivers and lakes in the Dianchi Lake basin, three-dimensional fluorescence spectroscopy and high-resolution mass spectrometry were employed to determine the features of dissolved organic matter (DOM) components. According to the research results, the DOM components in rivers and lakes in the Dianchi Lake basin were dominated by humic-like substances and affected by seasonal changes to a certain extent. DOM in Dianchi Lake is affected by the macrophytes and algae distribution as well as inflowing rivers, but the dominant factors are different in dry and rainy seasons. PCA results indicated that DOM components had relatively high relevance to water quality indicators, especially COD and TN. In conclusion, Lake ecosystem status and pollution levels can be characterized by DOM to some extent, the DOM components in the Dianchi Lake are prone to humification with the implementation of wastewater treatment and aquatic ecological restoration projects, as reflected in the improved water quality index.