[Spectral Evolution Characteristics of DOM in Sediment Interstitial Water During the Formation Stage of Thermal Stratification in the Main Reservoir Area of the Zhoucun Reservoir].

Based on three-dimensional fluorescence spectra (EEMs) combined with parallel factor analysis (PARAFAC), and ultraviolet-visible (UV-Vis) spectra, we analyzed the vertical distribution and characteristics of dissolved organic matter in sediment interstitial water during the formation stage of thermal stratification in the Zhoucun Reservoir. The results show that the UV-Vis absorption coefficient varies between -400% and 400%, indicating the different properties of DOM(dissolved organic matter) at different depths. The changes of E2/E3 show that the proportion of fulvic acid in DOM increases with the stratification of the reservoir and fulvic acid accounts for the main proportion with autochthonous characteristics based on E3/E4>3.5 and >1. Two fulvic-like substances (C1, C3), two protein-like substance (C2, C5), and two humic-like substances (C4, C6) were identified with the PARAFAC model. Moreover, fulvic-like and protein-like substances account for most of substances. The total DOM fluorescence intensity and the fluorescence intensity of each component show a decreasing trend with the occurrence of stratification and exhibit significant vertical and temporal differences. Based on the analysis of FI, HIX, BIX, and in sediment interstitial water, the high BIX, FI, and low HIX indicate that the DOM of sediment interstitial water has strong autochthonous components and original characteristics of aquatic bacteria.