Complexion between mercury and humic substances from different landfill stabilization processes and its implication for the environment
- 作者：Xiaoli Chai ; xlchai@mail.tongji.edu.cn ; xlchai@tongji.edu.cn ; Guixiang Liu ; Xin Zhao ; Yongxia Hao ; Youcai Zhao
- 关键词：Humic substances ; Mercury ; Landfill stabilization processes ; EEM
- 刊名：Journal of Hazardous Materials
- 出版年：2012
- 期刊代码：50_03043894
- 类别：ce
- 出版时间：30 March, 2012
- 卷：209-210
- 期：Complete
- 页码：59-66
- 文件大小：1294 K
摘要
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.