Seasonal characterization and identification of dissolved organic matter (DOM) in the Pearl River, China

Dissolved organic matter (DOM) is considered to be one of active organic carbon components in river water, and its characteristics would affect quality of drinking water if such a river is used for the purpose. DOM in the Pearl River around metropolitan Guangzhou and its six fractions obtained by sequential resins separation and their percentage distribution of total organic carbon (TOC), the UV absorbance at 254 nm (UV254), and the specific ultraviolet absorbance (SUVA254) were determined. Meanwhile, fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to examine the biodegradable and structural characteristics of DOM. The results showed that the values of TOC, UV254, and SUVA254 changed with season. Especially, SUVA254 was lower than 3 L (mg m)(-1), indicating that the hydrophilic fractions were the major components of the DOM. Furthermore, fluorescence spectroscopy revealed the dominant presence of humic-like, fulvic-like, and protein-like fluorophores. Fluorescence index (FI) in four seasons was associated with allochthonous DOM sources and biological DOM. FTIR spectroscopy suggested the feature of DOM with some specific groups (e.g., carbohydrate C-O, amid C═O).