Characteristic Analysis of Dissolved Organic Matter in Different Surface Waters

In order to understand the characteristics of dissolved organic matter (DOM) in different surface waters, the Ganjiang River and Poyang Lake were studied from four aspects: hydrophilicity/hydrophobicity, SUVA, molecular weight distribution and three-dimensional fluorescence characteristics. The results of hydrophilicity and hydrophobicity analyses show that as a whole the hydrophobic fractions and the hydrophilic fractions in the two surface waters each accounted for roughly half, and the high hydrophobic fraction (HPO) and neutral hydrophilic fraction (N-HPI) accounted for a relatively high amount, while the transphilic fraction (TPI) and charged hydrophilic fraction (C-HPI) had less content, in which the proportions of HPO, N-HPI, TPI and C-HPI (calculated as DOC) in the Ganjiang River were 37.28%, 38.99%, 14.54% and 9.19%, respectively. The SUVA values of the fractions in the two surface waters were different. The SUVA values (4.47, 3.44, 4.14) of the HPO, TPI, and C-HPI in the Ganjiang River were much higher than that of the N-HPI (1.22). However, the SUVA value (1.49, 1.51) of the HPO and TPI in the Poyang Lake were slightly higher than that of the C-HPI (1.00) and N-HPI (0.70). Moreover, the molecular weight distribution show that the molecular weight of DOM in the two surface waters presented a relatively similar rule, i.e. the DOM with a medium molecular weight (1-10 kDa) was the main component, and it also contained a small amount of DOM with a small molecular weight (< 1 000 Da), while for the high molecular weight (>10 kDa) no response peak appeared in the region. Three-dimensional fluorescence spectroscopy show that the surface waters were mainly humic acid-like hydrophobic DOM such as fulvic acid and humic acid, but the protein-like fluorescence peaks in the surface water of Poyang Lake were more obvious than those in the Ganjiang River. This research idea provids a reference for understanding the characteristics of dissolved organic matter in raw water from different sources, and the research results also offer a theoretical basis for taking reasonable control measures (such as ozone oxidation, activated carbon adsorption or membrane filtration technology, etc.).