title: Identifying the sources and fate of anthropogenically impacted dissolved organic matter (DOM) in urbanized rivers.
abstract: Anthropogenic activities have dramatically changed the loads and compositions of dissolved organic matter (DOM) in urbanized streams. In this study, the spatial and temporal variations of DOM in the anthropogenically impacted Zhujiang River were investigated by analyzing the water samples in an upstream, urbanized area and downstream of the rivers on different days of one year. The results indicated that the levels of dissolved organic carbon (DOC) and total phosphorus (TP) were unaffected by seasonal changes, but the specific UV254 absorbance (SUVA) values and the total nitrogen (TN) content were greater in the winter than those in the summer. Parallel factor (PARAFAC) analysis of the excitation emission matrices (EEM) revealed the presence of three anthropogenically derived components [tryptophan-like (C1) and tyrosine-like proteins (C3) and anthropogenic humic substances (C5)] in the urbanized rivers, and they had greater seasonal and spatial variability than the terrestrial and microbial humic substances (C2 and C4). Cluster analysis revealed that treated wastewater was an important source of DOM in the urbanized streams. Photodegradation experiments indicated that the DOM in the populous area of the rivers had greater photodegradation potentials than that in the downstream region or in the natural waters. Interestingly, that the anthropogenic humic substances (C5) were considerably more photoreactive than the other four PARAFAC components, which exhibited a decrease of 80% after exposure to sunlight for 0.5 d. This study suggests that the treated wastewater could be an important input to the DOM in the urbanized rivers and the naturally occurring photodegradation could help in eliminating the anthropogenic DOM during their transport.
authors.affiliation: SYSU-HKUST Research Center for Innovative Environmental Technology (SHRCIET), School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China. fgmeng80@126.com
authors.forename: Fangang
authors.initials: F
authors.lastname: Meng
authors.forename: Guocheng
authors.initials: G
authors.lastname: Huang
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Zengquan
authors.initials: Z
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Cao
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Sun
mesh_terms: D002244:Carbon / Q000032:analysis; D002681:China; D016000:Cluster Analysis; D003627:Data Interpretation, Statistical; D005618:Fresh Water / Q000032:analysis*; D006812:Humic Substances / Q000032:analysis; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D010782:Photolysis; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D014507:Urbanization; D014865:Waste Disposal, Fluid; D062065:Wastewater; D060753:Water Quality
chemical_list: D002244:Carbon; D006812:Humic Substances; D009584:Nitrogen; D010758:Phosphorus; D062065:Wastewater
keywords: Fluorescent dissolved organic matter (FDOM); Parallel factor analysis; Rivers; Wastewater effluent; Water quality