Abstract: 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.).

Key words: dissolved organic matters (DOM), hydrophilicity/hydrophobicity, molecular weight distribution, three-dimensional fluorescence