[Characterizing Structural Composition of Dissolved and Particulate Organic Matter from Sediment Pore Water in a Urban River Using Excitation-Emission Matrix Fluorescence with Self-Organizing Map].

Excitation-emission matrix (EEM) fluorescence with self-organizing map was applied to characterize structural composition and spatial distribution of dissolved (DOM) and particulate (POM) organic matter from sediment pore water in a typical urban river. Ten sediment pore water samples were collected from the mainstream of Baitabuhe River in Shenyang City of northeast China, along a human impact gradient, i. e. river source, rural and urban regions. DOM and POM were extracted from the pore water, and their EEM fluorescence spectra were measured. ƒ450/500 of DOM ranged from 1.82 to 1.91, indicating that DOM is mainly from microbial source; ƒ450/500 of POM ranged from 1.42 to 1.68, suggesting that POM derived from land. Four components were identified from DOM and POM fractions by self-organizing map, which included tyrosine-like, tryptophan-like, fulvic-like and humic-like matters. Tyrosine-like originated from fresh and less-degraded material with a high potential for oxida- tion, which was considered as representative components of DOM and POM. Tryptophan-like was associated with microbial byproduct-like material, and can indicate microbial activities. The abundance sum of all components in DOM is roughly 2 times more than that in POM. The mean relative abundance of tyrosine-like was more than 50%, while tryptophan-like was about 18.6%-23.1%. Abundance of fulvic-like was much more than that of humic-like, but they were only a small proportion of organic matter fractions. Based on principal component analysis, the characteristics of DOM and POM distinctly were distributed along river source, rural region and urban region, proving that the river was deeply influenced by human activity.