title: Complexion between mercury and humic substances from different landfill stabilization processes and its implication for the environment.
abstract: Three-dimensional excitation emission matrix (EEM) fluorescence spectroscopy was employed to investigate the structural properties and Hg(II)-binding behavior of humic substances (HS) extracted from different landfill stabilization processes. The EEM fluorescence properties of humic acid (HA) are characterized by intense fluorescence at Ex/Em=440/500 nm and Ex/Em=380/460 nm. Two relatively strong fluorescence peaks appeared in the region of Ex/Em=260-290/350-370 nm with the landfill time extended, which represented a protein-like or soluble microbial byproduct structure. The fluorescence EEM spectrum of fulvic acid (FA) featured a prominent peak of strong relative fluorescence intensity (FI=1598) at Ex/Em=330/440 nm (peak C) accompanied by a weak fluorophore (FI=594) located at Ex/Em=275/445 nm (peak D). There were strong interactions between HA and Hg, and the overall stability constant of Hg(II)-HA was mainly determined by the abundant O-ligands existing in HA. FA had a much higher Hg(II)-complexing capacity compared to HA samples, which may be ascribed to its relatively high content of carboxylic groups. The Hg(II)-complexing capacity of HA tended to decrease with stabilization process extension. The much higher Hg(II)-complexing capacity of FA than that of HA implied that FA played an important role in binding Hg(II) in early landfill stabilization process.
authors.affiliation: The State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092, China. xlchai@mail.tongji.edu.cn
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Chai
authors.forename: Guixiang
authors.initials: G
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.forename: Yongxia
authors.initials: Y
authors.lastname: Hao
authors.forename: Youcai
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D006812:Humic Substances; D008628:Mercury / Q000737:chemistry*; D012037:Refuse Disposal; D013050:Spectrometry, Fluorescence
chemical_list: D006812:Humic Substances; D008628:Mercury