Characterization of DOM Composition and Origin Using Three-dimensional Fluorescence Spectroscopy Coupled with Region Integration Method in Qixing Wetland

Based on the monitoring of water quality of Qixing wetland, the three-dimensional fluorescence spectroscopy combined with fluorescence regional integral (FRI) analysis were used to analyze the fluorescence characteristics of the dissolved organic matter (DOM) in the water body of Qixing wetland. The correlation of the DOM composition, humification degree and polluting sources and other water quality parameters were explored. The results showed that the Qixing wetland could purify pollutants from tributaries. The CODCr concentration in the effluent of the wetland met grade V standard (GB 3838-2002), and ammonia nitrogen and total phosphorus were still the main pollutants in the water. The mean value of fluorescence index (f450/500) was 1.82, indicating biological origin of the DOM. Humification index (r_B,D) is overall low, indicating higher humification degree of wetland water and more serious organic pollution. The fluorescence spectra were divided into five components by fluorescence regional integration method. Aromatic protein II was the largest content which accounted for 37.51%-54.2% of total DOM and mainly related to sewage discharge. DOC significantly correlated with aromatic protein I, II, soluble microbial metabolites and humic substances. TP had significant correlation with aromatic protein substances II, fulvic acids and humic substances. Thus, three-dimensional fluorescence spectroscopy coupled with region integral method can be used in the research of water DOM composition and sources of contaminants.