title: Tracking fluorescent dissolved organic matter in multistage rivers using EEM-PARAFAC analysis: implications of the secondary tributary remediation for watershed management.
abstract: Profound understanding of behaviors of organic matter from sources to multistage rivers assists watershed management for improving water quality of river networks in rural areas. Ninety-one water samples were collected from the three orders of receiving rivers in a typical combined polluted subcatchment (diffuse agricultural pollutants and domestic sewage) located in China. Then, the fluorescent dissolved organic matter (FDOM) information for these samples was determined by the excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC). Consequently, two typical humic-like (C1 and C2) and other two protein-like (C3 and C4) components were separated. Their fluorescence peaks were located at λ ex/em = 255(360)/455, <250(320)/395, 275/335, and <250/305 nm, which resembled the traditional peaks of A + C, A + M, T, and B, respectively. In addition, C1 and C2 accounted for the dominant contributions to FDOM (>60 %). Principal component analysis (PCA) further demonstrated that, except for the autochthonous produced C4, the allochthonous components (C1 and C2) had the same terrestrial origins, but C3 might possess the separate anthropogenic and biological sources. Moreover, the spatial heterogeneity of contamination levels was noticeable in multistage rivers, and the allochthonous FDOM was gradually homogenized along the migration directions. Interestingly, the average content of the first three PARAFAC components in secondary tributaries and source pollutants had significantly higher levels than that in subsequent receiving rivers, thus suggesting that the supervision and remediation for secondary tributaries would play a prominent role in watershed management works.
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China.|Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Yuhangtang Road 866, Hangzhou, 310058, People's Republic of China.
authors.forename: Zeyu
authors.initials: Z
authors.lastname: Nie
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China.|Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Yuhangtang Road 866, Hangzhou, 310058, People's Republic of China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China.|Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Yuhangtang Road 866, Hangzhou, 310058, People's Republic of China.
authors.forename: Haomin
authors.initials: H
authors.lastname: Huang
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China.|Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Yuhangtang Road 866, Hangzhou, 310058, People's Republic of China.
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Fang
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China.|Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Yuhangtang Road 866, Hangzhou, 310058, People's Republic of China.
authors.forename: Chen
authors.initials: C
authors.lastname: Xu
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China.|Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Yuhangtang Road 866, Hangzhou, 310058, People's Republic of China.
authors.forename: Jianyu
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China.|Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Yuhangtang Road 866, Hangzhou, 310058, People's Republic of China.
authors.forename: Xinqiang
authors.initials: X
authors.lastname: Liang
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China. shijiyan@zju.edu.cn.|Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Yuhangtang Road 866, Hangzhou, 310058, People's Republic of China. shijiyan@zju.edu.cn.
authors.forename: Jiyan
authors.initials: J
authors.lastname: Shi
mesh_terms: D002681:China; D004784:Environmental Monitoring / Q000379:methods*; D052918:Environmental Restoration and Remediation; D005163:Factor Analysis, Statistical; D005453:Fluorescence; D006812:Humic Substances / Q000032:analysis*; D025341:Principal Component Analysis; D045483:Rivers / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014872:Water Movements; D014873:Water Pollutants / Q000032:analysis*; D060753:Water Quality
chemical_list: D006812:Humic Substances; D014873:Water Pollutants
keywords: Combined pollution; EEM-PARAFAC; FDOM; Secondary tributaries; Subcatchment; Watershed management