Fluorescence excitation-emission matrix combined with regional integration analysis to characterize the composition and transformation of humic and fulvic acids from landfill at different stabilization stages
Fluorescence excitation-emission matrix combined with regional integration analysis to characterize the composition and transformation of humic and fulvic acids from landfill at different stabilization stages
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荧光激发发射矩阵结合区域积分分析表征不同稳定阶段垃圾填埋场腐殖酸和黄腐酸的组成和转化
DOI：
10.1016/j.wasman.2011.10.011
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发表时间：
2012-03-01
期刊：
影响因子：
8.1
通讯作者：
Zhao Youcai
中科院分区：
文献类型：
--
作者：
Chai Xiaoli;Liu Guixiang;Zhao Youcai
采用荧光激发发射矩阵光谱（EEMS）结合荧光区域积分（FRI）技术研究了垃圾填埋场中腐殖酸（HA）和富里酸（FA）的组成和转化规律。不同填埋年限腐殖酸的EEM特征为两种典型的荧光发色团，其Ex/Em对分别位于Ex = 420-470 nm/Em = 490-530 nm和Ex = 345-375 nm/Em = 450-465 nm。FA的EEM由另外两种明显不同的荧光团表征，其中Ex/Em对在Ex = 315-335 nm/Em = 420-440 nm和Ex = 255-275 nm/Em = 425-455 nm处。结果表明，从1989年垃圾中提取的HA是由小稠环芳香结构与蛋白质样链连接而成。与1992年垃圾中提取的HA相比，1996年垃圾中提取的HA具有更高的荧光强度和更低的t（（B，A））值（B峰与A峰荧光强度的比值）。它含有低摩尔质量组分，芳香缩合度低，更容易被氧化的取代基。这表明，填埋时间强烈影响腐殖酸的EEM特性，腐殖化程度随着填埋时间的增加而增加。随着HA浓度的增加，荧光强度向长波区域红移，表明浓度对HA的荧光特性有很大影响。pH（2-12）对HA和FA的荧光强度也有显著影响，但对荧光峰位无影响。FRI结果表明，随着浓度的增加，各结构组分之间的相互作用增强，小分子量单元趋于聚集或被掩蔽成更复杂、更大的结构。pH值对HA荧光强度的影响主要是通过分子构型来实现的，而荧光强度随pH值的变化可能是由于FA的不同取代基所致。(C)2011爱思唯尔有限公司保留所有权利。
Fluorescence excitation-emission matrix spectroscopy (EEMs) combined with fluorescence regional integration (FRI) analysis was used to investigate the composition and transformation of humic acid (HA) and fulvic acid (FA) from landfill. The EEMs of HAs at different landfill ages were characterized by two typical fluorescence chromophores with Ex/Em pairs at Ex = 420-470 nm/Em = 490-530 nm and Ex = 345-375 nm/Em = 450-465 nm. EEMs of FA were featured by other two distinctly different fluorophores with Ex/Em pairs at Ex = 315-335 nm/Em = 420-440 nm and Ex = 255-275 nm/Em = 425-455 nm. The results show that HA extracted from the refuse disposed in the year of 1989 was formed by connecting small-condensed aromatic structures with protein-like chains. Compared with HA extracted from the refuse disposed in the year of 1992, HA extracted from the refuse of 1996 had a higher fluorescence intensity and lower t((B,A)) (the ratio of the fluorescence intensities of peak B and peak A) value. It contained low molar mass components, low aromatic condensation degree, and more easily oxidized substituents. This indicates that the landfill time strongly affects the EEMs characteristics of HA, and that the humification degree of HA increases with the landfill time. A red shift to a longer wavelength region and an increase of fluorescence intensity were observed when the concentration of HA was increased, suggesting that concentration had a great influence on the fluorescence characteristics of HAs. pH (2-12) also had significant effects on the fluorescence intensity, although it exerted no effect on the peak position of fluorescence of HA and FA. The results of FRI show that increasing concentration lead to more interactions among various structure components and that small molecular weight units tend to aggregate or be masked into more complicated and larger structures. The pH influence on the fluorescence intensity of HA seems mainly through molecular configuration, while the fluorescence intensity change with pH may be due to various substituents of FA. (C) 2011 Elsevier Ltd. All rights reserved.