[Characterization of isolated fractions of NOM from Songhua River].

Natural organic matter (NOM) was concentrated from Songhua River using a reverse osmosis system. The hydrophobic fraction (HyO), hydrophilic fraction (HyI), fulvic acid (FA) and humic acid (HA) were fractionated by the XAD resin, and a commercial humic acid (CHA) was used for comparison. The FA fraction predominant in natural water and account for the large part of DOC, and the aromaticity of these fractions followed the order HA> HyO> FA> HyI. A weak relationship exists between the E4/ E6 and aromaticity. FTIR spectra revealed that the degree of saturation among these fractions was in the order of HyO = FA > HyI > HAM=CHA. Gel chromatograph results showed that the weaker ultraviolet-adsorption fraction of NOM contributed to the most part of molecular weight. Potentiometric titration indicated that the total organic acidity was in the range of 9.84 - 12.15 meq/g, and carboxylic acidity decrease in the order of CHA> HyI > HyO > NOM > FA > HA. 1H NMR spectra demonstrated that NOM and the isolated fractions were predominated by aliphatic functional groups.