摘要
从Pahokee泥炭土中连续碱抽提分离出 8个不同的腐殖酸级分 ,并对每一级分进行了元素分析、傅里叶变换红外光谱 (FTIR)、固态1 3C核磁共振 ( 1 3CNMR)、高效排阻色谱 (HPSEC)等一系列定性、定量研究。结果表明 :所分离出的 8个腐殖酸级分存在明显的结构性质差异 ,随提取程度的增加 ,O C原子比由 0 5 2减少到0 3 6,H C原子比由 1 .0 5增加到 1 5 2 ,相应于结构中含氧基团的减少和脂族基的增加 ,表观分子量也由 7.7K增加到 2 2 1K。同时 ,1 3CNMR显示长链脂肪碳结构由无定型向晶型转变。此工作表明在所研究的腐殖酸中可能存在分别具有芳香或脂肪特性的两类腐殖酸结构 ,每种类型都有不同的分子量分布、元素组成、基团结构和母质来源。在特定的环境因素下 ,不同类型的腐殖酸会共存于同一体系中 。
Eight humic acid fractions were progressively extracted from a Pahokee peat soil and were characterized by terms of qualitative and quantitative techniques including elemental analysis fourier transform infrared spectrometry (TFIR), soild state C-13 nuclear magnetic resonance (C-13 NMR), high performance size exclusion chromatography (HPSEC). This study demonstrated distinct compositional and structural differences existed in the eight humic acid fractions. The O/C atomic ratio decreased from 0.52 to 0.36 whereas the H/C atomic ratio increased from 1.05 to 1.52 as a function of extraction. This trend corresponded to the decreasing contents of oxygen-containing groups and the increasing contents of aliphatic groups. The apparent molecular weight increased from 7.7 K to 22.1 K. Moreover, the structure of the aliphatic chain varied from amorphism to regularity indicated by C-13 NMR. The study suggested that there might be two types of humic acid structure associated in the peat, exhibition, element composition, group structure and source material. Under special environments, humic acids with different types can coexist in a system, which increases the heterogeneity of humic substances.
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2002年第11期1303-1307,共5页
Chinese Journal of Analytical Chemistry
基金
国家自然科学基金资助项目 (No .40 0 72 0 94和No .40 172 10 5 )
关键词
分子结构
泥炭土
腐殖酸
连续碱抽提
傅里叶变换红外光谱
碳-13
核磁共振
高效排阻色谱
特征
peat soil humic acid
progressive extraction
Fourier transform infrared spectrometry
C-13 nuclear magnetic resonance
high performance size exclusion chromatography
