嘉陵江重庆段沉积物中腐殖酸的特性研究

从嘉陵江不同河段沉积物中提取腐殖酸,采用元素分析、傅里叶变换红外光谱(FTIR)和荧光光谱对腐殖酸的化学组成和结构特征进行研究.元素分析显示,腐殖酸样品的H/C,O/C和C/N摩尔比具有明显差别,说明其化学组成和结构特征存在差异.FTIR分析显示,腐殖酸样品的官能团结构相似,含有大量的羧基、羟基、羰基等活性官能团,芳香族结构特征显著.三维荧光光谱(3DEEM)显示,腐殖酸样品在Ex/Em=270/390 nm和Ex/Em=230/350 nm附近出现两个特征峰a和b,其荧光强度Ia/Ib=1.31～2.53,揭示其含有多种类型的荧光发色基团.荧光指数f450/500=1.43～1.53,表明腐殖酸主要以陆源输入为主.

Studies on characterization of humic acids extracted from sediments in Chongqing section of the Jialingjiang River

Humic acids (HAs) were extracted from sediments of different segments in the Jialingjiang River. Fluorescence spectroscopy, elemental analysis and Fourier transform infrared (FTIR) spectrometry were used to investigate the chemical composition and structure characteristics of HAs. Elemental analysis showed that H/C, O/C, and C/N molar rations were significantly different among 4 HAs, which indicated their differences in chemical composition and structure characteristics. FTIR spectra revealed that HAs contained more carboxyl, hydroxyl and carbonyl functional groups, and aromatic structure was very obvious. The three dimensional fluorescence excitation-emission-matrix (3DEEM) spectra of HAs presented two main peaks (peak a and peak b) at Ex/Em = 270/390 nm and Ex/Em = 230/350 nm. The relative fluorescence intensities i(A)/I(b) varied from 1.31 to 2.53 for different HA samples, which revealed that they contained multiple molecule fluorophores. Fluorescence index (f4550/500 = 1.43-1.53) suggested that HAs mainly originated from terrestrial sources.