基于Py-GC-MS/MS技术的高寒草原土壤有机质不同组分指纹特征研究

采用热裂解气相色谱质谱联用(Py-GC-MS/MS)技术来研究高寒草原土壤有机质5个密度组分之间的指纹差异。对150种热解产物进行定性定量分析,并将其根据相似的化学性质分为:烷基类化合物、芳烃及多环芳烃、木质素、酚类物质、多糖、含氮化合物及几丁质。研究结果表明:在高寒草原土壤中,F1(密度为小于1.6g/cm~3)组分主要为植物碎屑,虽然该组份在整体土壤中质量含量较少(0.13%)但其有机质含量相对较高(5.7%),该组份中含有较多的木质素及长链烷基类化合物(主要来源于植物),且随着密度的增加,此类化合物的含量逐渐减少。F2(密度为1.6—1.8g/cm~3)、F3(密度为1.8—2.0g/cm~3)及F4(密度为2.0—2.25g/cm~3)3个组分化学性质相似,其有机化合物的含量在密度组分中呈现增加或减少的过渡状态。F5(密度大于2.25g/cm~3)组分是该土壤的主要组成部分,其质量含量高达98%,该组份中的微生物指纹信息(微生物来源的多糖及含氮化合物)均高于前4个组分。同时,芳烃及多环芳烃这类难降解的物质随着密度的增大逐渐累积,在F5组分中富集。

Study on the fingerprints of soil organic components in alpine grassland based on Py-GC-MS/MS Technology

The pyrolysis gas chromatography-mass spectrometry (Py-GC-MS/MS) technique was used to study the differences in five density components of soil organic matter in alpine grassland. In this study, 150 pyrolysis products were qualitatively and quantitatively analyzed, and they were classified according to their similar chemical properties into alkyl compounds, aromatics and polyaromatics, lignin, phenols, polysaccharides, N-compounds and chitin. This study found that in alpine grassland, the F1 component, which contains compounds whose densities are less than 1.6g/cm³ were composed of plant debris. Although the percentage of this component in the whole soil was low (only 0.13%), its organic content was relatively high (5.7%). The F1 component contained more lignin and long chain alkyl compounds, which were mostly from plants, and the content of these compounds decreased gradually as the density increased. The F2 (compound densities from 1.6 to 1.8g/cm³), F3 (compound densities from 1.8 to 2g/cm³), and F4 (compound densities from 2 to 2.25g/cm³) components had similar chemical properties, and their organic compound contents showed a transition state, which increased or decreased among the density components. The F5 (compound density greater than 2.25g/cm³) component is the major part of the soil where its content is as high as 98%. The microbial polysaccharides and N-compounds (mainly from microorganisms) in the F5 component were significantly higher than in the first four components, which indicated that the F5 component contained more microbial fingerprint information. The recalcitrant substances, such as aromatics and polyaromatics, were also found in the F5 fraction.