【摘要】 采用热裂解-气相-质谱(Pyr-TMAH-GC/MS)技术对长期不同施肥处理下太湖地区黄泥土本体土壤及水稳性团聚体中颗粒有机碳(POC)的化学组分进行了研究。结果表明,POC的热裂解产物主要来源于脂肪族化合物和木质素类化合物。木质素类化合物主要以愈疮木基丙烷(G)和p-羟苯基(P)两种木质素单体为主,从而揭示黄泥土POC积累中草本植物(水稻、油菜的残茬和秸秆)的输入贡献。脂肪族化合物主要为C8-C30脂肪酸甲基酯(FAMEs),且大多为偶数碳结构。施肥改变了各裂解产物在本体土壤和水稳性团聚体中的分布,从而使得不同施肥处理下各类化合物对POC稳定性的贡献出现了差异。化肥配施猪粪下木质素类化合物以及微生物源的脂肪族化合物均贡献于本体土壤POC的积累与稳定,而化肥配施秸秆下本体土壤POC的化学稳定性主要归因于高等植物源化合物的贡献,其次为微生物源脂肪族化合物。化肥配施有机肥下水稳性团聚体中较高的POC主要归因于植物源有机物质的分解贡献。本研究揭示了合理施肥下水稻土中有机碳的化学抗性组分在土壤有机碳积累中的促进作用,各组分的相对分布差异可指示有机碳积累的不同来源。更多还原

【Abstract】 Tetramethyla mmonium hydroxide(TMAH) thermochemolysis-gas chromatography/mass spectrometry(GC/MS) was employed to investigate the supramolecular structure of particulate organic carbon(POC) sampled from a Tai Lake paddy soil under a long-term field experiment with different fertilization systems.The chromatograms revealed peaks related to compounds derived from lignin and aliphatic compounds.The dominant lignin-derived compounds were mainly derivatives of guaiacyl(G) and p-hydroxyphenyl(P) structures,suggesting the contribution of a non-woody(grass) lignin type(mainly crop residues from rice and rape).The most abundant aliphatic compounds were C8-C30 fatty acid methyl esters(FAMEs) dominated by even-numbered carbon species,in which short chain FAMEs of microbial origin were prevalent.Soil fertilizations induced differences of the distribution of each thermochemolysis compound both in bulk soil and water-stable aggregations,and thereby the relative contribution of each compound to the stability of POC.Generally,the lignin compounds and aliphatic compounds of microbial origin contributed to the accumulation and stabilization of POC under the treatment of chemical fertilizer plus pig manure.Nevertheless,the enhanced POC under chemical fertilizer plus crop straw was attributed preferentially to aliphatic compounds of higher plant origin,followed by those of microbe origin.The higher POC content in water-stable aggregates under organic-inorganic fertilization treatments was supposed to be predominantly due to the decomposition of higher plants.The C stabilization by molecular recalcitrance is supposed to contribute to the C sequestration and stabilization in paddy soils under good managements,the relative distribution of which can indicate the different source of newly-accumulated soil organic C.更多还原