土壤中溶解性有机质分组组分的结构特征研究

以Leenheer的分组方法为基础 ,用XAD 8树脂将黄泥土中水溶性有机质 (DOM)按极性和电荷特性分为结构较为均一的不同组分 ,并采用元素分析、1 H NMR以及CP/MAS1 3 C NMR研究各组分的性质。初步认为 :三种不同利用方式下 (桑园、水田、水杉 )黄泥土中的DOM组成中疏水碱性组分 (HOB)含量很少 ,疏水中性组分 (HON)相对含量为 7%～ 1 5 %,亲水性组分 (HIM)是土壤DOM中最大组成部分 ,约占 35 %。元素分析、1 H NMR以及1 3 C NMR分析结果表明 :DOM各组分结构特征差异显著。HON以含有大量的长链烷烃为主要结构特征 ,并含有较多氨基酸、多肽类物质 ;疏水酸性组分 (HOA)的结构特征相似于土壤FA ,含有大量羧基 ,但与FA相比芳香族物质减少 ,碳水化合物增多 ;酸不溶组分 (AIM)以多酚类、腐殖质结合的碳水化合物为主要组成物质 ;HIM中则含有大量碳水化合物。

STRUCTURAL CHARACTERISTICS OF DISSOLVED ORGANIC MATTER FRACTIONS EXTRACTED FROM SOILS DIFFERENT IN LAND USE

Based on a modified Leenheer fractionation scheme,dissolved organic matter (DOM) extracted from Huang-nitu under different land use were fractioned according to their polarities and charge characteristics by using XAD-8 resin.The characteristics were studied with the aid of elemental analysis,¹H-NMR and CP/ MAS-¹³C-NMR spectroscopy.It was preliminarily found that of the total DOM extracted from the paddy soils,HIM predominated,accounting for about 35%,HON accounted for 7%~15% and HOB for a little.As is shown by the elemental analysis,¹H-NMR and ¹³C-NMR spectra,HON was characterized mainly by longchain alkylate with 77.13% of aliphatic C.N from the DOM could be found primarily in fraction HON.Comparison between the spectra of HOA and fulvic acids (FA) indicated that both contained a large amount of carboxylic groups and that the former contained more carbohydrates and less aromaticity.Finally,fraction AIM consisted of high-branched polyphenols and humic bound carbohydrates,and fraction HIM contained a high amount of carbohydrates.