Investigating Spectral Characteristics and Spatial Variability of Dissolved Organic Matter Leached from Wetland in Semi‐Arid Region to Differentiate Its Sources and Fate

Abstract

Dissolved organic matter (DOM) collected from different sampling sites in Lake Wuliangsuhai (Inner Mongolia Autonomous Region of China) was investigated using UV–Vis absorption and fluorescence spectroscopy. The three indices, SUVA280 and two spectral slopes (S275–295 and S350–400), were used to detect the change in the aromatic structure of DOM. DOM aromaticity was lower at sites W1 and W3, where industrial wastewater and domestic sewage, and agricultural drainage, contributed respectively. The humification index also indicated a low humification degree at sites W1 and W3, and high humification degree in other sites with relatively better water quality. Fluorescence regional integration (FRI) analysis has been used to quantitatively analyse fluorescence excitation–emission matrix spectra. The results showed that external contaminants can influence the distribution of Pi,n values from the FRI analysis. Serious pollution area obtained a relatively high Pp value. A significant negative correlation between Ph/Pp and f450/500 indicated the terrestrial or autochthonous sources of DOM. Therefore, the spectroscopic techniques combined with regional integration analysis can be used as a useful tool for investigating and assessing the lake ecological environment.