Spectral Characteristics of Dissolved Organic Matter (DOM) Derived from Water and Sediment in Normal Flow Period of the Intersection Zone of Jing River and Wei River

As the representative component for eco-environmental researchers, dissolved organic matter (DOM) is playing a significant role for the indication effect on environmental quality and efficiency assessment on remediation approaches. Nowadays, it lacks related investigation on DOM derived from rivers and sediments, and the advanced discussion is in urgent need because of the dynamic variations of experimental target, such as spatial-temporal condition, hydrological condition, environmental condition and research dimension. The spectral approaches, including elemental analysis, ultraviolet spectra (UV), Fourier transform infrared spectroscopy (FT-IR), Raman spectra (Raman), three dimensional excitation emission matrix fluorescence spectroscopy (3D-EEMs) and nuclear magnetic resonance (NMR) were used to reveal the characteristics of DOM derived from water and sediment samples in the intersection zone of Jing River and Wei River (Gaoling District, Xi' an City, Shaanxi Province). The results showed: the ratios of H/C and N/C for DOM in sediment are higher than that of DOM in water, suggesting the saturation degree in DOM from sediment are higher with more content of nitrogen. The UV absorbance of DOM decreases with the increasing of wave length, and obvious absorption region (240 similar to 310 nm) appears in DOM from sediment. The functional groups of -OH, C=C and C-O could be found in DOM from FTIR spectra, and the characteristics might be more complicated in sediment for various peak shapes and intensities. The Raman spectra of DOM in water are similar to that of the sediment. The fluorescence peaks of DOM in water are regarded as visible tryptophane-like and UV fulvic-like components, mainly from terrestrial source; while fluorescence peaks of DOM in sediment belong to UV fulvic-like fluorescence without protein-like fluorescence peaks being detected. The principal carbon chains are similar in DOM samples from water and sediment, and the aliphatic characteristics are more obvious for the latter, which contains more carbohydrate-binding hydrogen than aromatic-binding hydrogen and gamma-H. It proves that DOM in water mainly comes from terrestrial source, and DOM in sediment is more complicated and fresher. The achievements are significant to reveal the microscopic characteristics and environmental behavior of DOM in representative systems.