Applying fluorescence spectroscopy and multivariable analysis to characterize structural composition of dissolved organic matter and its correlation with water quality in an urban river

Excitation–emission matrix fluorescence spectroscopy combined with multivariable analysis was employed to discriminate structural component of dissolved organic matter (DOM) in Xihe River, an urban river, located in western Shenyang City of China, and to reveal its correlation with water quality. Eight water samples were collected along the river across the centralized wastewater-discharge region and the dispersed wastewater-discharge region. Water quality had deeply deteriorated in the river. Based on DOM fluorescence spectroscopic properties, DOM was composed of tyrosine-like, tryptophan-like, soluble microbial by-product-like, fulvic-like and humic-like materials, among which protein-like material was dominant in the DOM fractions. The DOM in the centralized wastewater-discharge region had a lower level of aromaticity than that in the dispersed wastewater-discharge region, and its humification degree was lower than that in the latter too. Key factors for the trophic state contained NH₄-N, DO, DOC, TP, Φ _2,n and Φ _4,n by multivariable analysis. DOM was mainly derived from treated and untreated industrial wastewater with weak biodegradability.