title: Fluorescence spectroscopy reveals accompanying occurrence of ammonium with fulvic acid-like organic matter in a fluvio-lacustrine aquifer of Jianhan Plain.
abstract: This study is the first to investigate the simultaneous presence of NH4 (+) and fluorescent organic matter components (FOCs) from a fluvio-lacustrine aquifer in Central Jianghan Plain. Sediment, groundwater, and surface water samples were collected for the sediment organic matter extraction, 3D fluorescence spectroscopy characterization, and/or hydrochemical analysis. NH4 (+) and dissolved organic carbon was ubiquitous in the groundwater. The fluorescence spectroscopy revealed good relationships between NH4 (+) and fulvic acid-like components (FALCs) in the groundwater and sediment-extracted organic matter (SEOM) solutions. NH4 (+) also exhibited significant positive correlation with protein-like component (PLC) (p < 0.001), with the stronger in the SEOM solutions than that in groundwater. Comparisons of spectroscopic indices [e.g., humification index (HIX), biological index (BIX), spectra slope (S275-295), and specific UV absorbance (SUVA254)] between the groundwater and SEOM solutions revealed more labile properties of SEOM. This result indicates that the decreasing NH4 (+)-FOCs correlations of groundwater relative to sediments may be attributed to microbial degradation. Factor analysis identifies important factors that cause NH4 (+) occurrence in the groundwater. The accompanying increase of FALC (C1) and NH4-N with the mole concentration of the normalized HCO3 (-)/(Ca(2+)+Mg(2+)) and [H(+)] suggests that couple effects of various biodegradations simultaneously occur in the aquifer, promoting the occurrence of NH4-DOMs.
authors.affiliation: School of Environmental Studies and State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, China. shuangbinghuang@126.com.|Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China. shuangbinghuang@126.com.|Hebei Key Laboratory of Groundwater Remediation, Shijiazhuang, 050061, China. shuangbinghuang@126.com.|Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA, 99352, USA. shuangbinghuang@126.com.
authors.forename: Shuangbing
authors.identifier: http://orcid.org/0000-0001-5386-0352
authors.initials: S
authors.lastname: Huang
authors.affiliation: School of Environmental Studies and State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, China. yx.wang@cug.edu.cn.
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Environmental Studies and State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, China. mateng@cug.edu.cn.
authors.forename: Teng
authors.initials: T
authors.lastname: Ma
authors.affiliation: Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China.|Hebei Key Laboratory of Groundwater Remediation, Shijiazhuang, 050061, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China.|Hebei Key Laboratory of Groundwater Remediation, Shijiazhuang, 050061, China.
authors.forename: Long
authors.initials: L
authors.lastname: Zhao
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis*; D001578:Benzopyrans / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring; D060587:Groundwater / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D064751:Ammonium Compounds; D001578:Benzopyrans; D014874:Water Pollutants, Chemical; C005023:fulvic acid
keywords: 3D fluorescence spectroscopy; DOM; Factor analysis; Groundwater; Hydrochemistry; NH4 +