title: Changes and characteristics of dissolved organic matter in a constructed wetland system using fluorescence spectroscopy.
abstract: Domestic wastewater was treated by five constructed wetland beds in series. Dissolved organic matter (DOM) collected from influent and effluent samples from the constructed wetland was investigated using fluorescence spectroscopy combined with fluorescence regional integration (FRI), parallel factor (PARAFAC) analysis, and two-dimensional correlation spectroscopy (2D-COS). This study evaluates the capability of these methods in detecting the spectral characteristics of fluorescent DOM fractions and their changes in constructed wetlands. Fluorescence excitation-emission matrix (EEM) combined with FRI analysis showed that protein-like materials displayed a higher removal ratio compared to humic-like substances. The PARAFAC analysis of wastewater DOM indicated that six fluorescent components, i.e., two protein-like substances (C1 and C6), three humic-like substances (C2, C3 and C5), and one non-humic component (C4), could be identified. Tryptophan-like C1 was the dominant component in the influent DOM. The removal ratios of six fluorescent components (C1-C6) were 56.21, 32.05, 49.19, 39.90, 29.60, and 45.87 %, respectively, after the constructed wetland treatment. Furthermore, 2D-COS demonstrated that the sequencing of spectral changes for fluorescent DOM followed the order 298 nm → 403 nm → 283 nm (310-360 nm) in the constructed wetland, suggesting that the peak at 298 nm is associated with preferential tryptophan fluorescence removal. Variation of the fluorescence index (FI) and the ratio of fluorescence components indicated that the constructed wetland treatment resulted in the decrease of fluorescent organic pollutant with increasing the humification and chemical stability of the DOM.
authors.affiliation: Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 610031, People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yao
authors.affiliation: Sichuan Academy of Environmental Sciences Sichuan, Chengdu, 610041, People's Republic of China.
authors.forename: Yun-Zhen
authors.initials: YZ
authors.lastname: Li
authors.affiliation: Key Laboratory of Development and Application of Rural Renewable Energy, Ministry of Agriculture, Biogas Institute of Ministry of Agriculture, No.13 Sec 4 Renmin Road South, Chengdu, 610041, People's Republic of China. gxj530520@126.com.|College of Resources and Environment, Chengdu University of Information Technology, No.24 Block 1, Xuefu Road, Chengdu, 610225, People's Republic of China. gxj530520@126.com.
authors.forename: Xu-Jing
authors.initials: XJ
authors.lastname: Guo
authors.affiliation: Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 610031, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
authors.affiliation: Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 610031, People's Republic of China.
authors.forename: Ping-Ping
authors.initials: PP
authors.lastname: Gao
authors.affiliation: Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 610031, People's Republic of China.
authors.forename: Ying-Pei
authors.initials: YP
authors.lastname: Zhang
authors.affiliation: Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 610031, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Yuan
mesh_terms: D009930:Organic Chemicals / Q000032:analysis*; D012996:Solutions; D013050:Spectrometry, Fluorescence / Q000379:methods; D062065:Wastewater / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*; D053833:Wetlands
chemical_list: D009930:Organic Chemicals; D012996:Solutions; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Constructed wetland; Dissolved organic matter; Fluorescence excitation–emission matrix; Fluorescence regional integration; Parallel factor analysis; Two-dimensional correlation spectroscopy