青藏高原北部土壤正构烷烃氢同位素及物源意义

采用正构烷烃及其单体氢同位素组成特征相结合的方法研究了青藏高原北部多年冻土区表层土壤正构烷烃（C₂₁~C₃₃）的生物来源.研究表明：表层土壤中正构烷烃呈双峰型和三峰型的分布特征，表明其具有多个生物来源.长链长正构烷烃（C₂₅~C₃₃）主要来源于陆源高等植物.表层土壤中长链长正构烷烃（C₂₅~C₃₃）中奇碳数正构烷烃的δD值比偶碳数的整体偏轻，原因可能是两者的生物合成途径不同.对中等链长正构烷烃聚类分析后分为两种类型，类型I的中等链长正构烷烃（C₂₁~C₂₄）主要来源于陆源高等植物，类型Ⅱ的中等链长正构烷烃主要来源于细菌等微生物降解的产物.表层土壤样品（FHS-10、TG2-10和TG3-10）中等链长的正构烷烃δD值最轻，应为δD值偏轻的水源和细菌等微生物降解共同作用的结果.

n-Alkanes hydrogen isotopes in soil from the northern region,Tibetan Plateau: Implications for sources of organic matter

Origins of n-alkanes in surface soil from permafrost regions in the northern part of the Tibetan Plateau were studied by the distributions of n-alkanes, and the δD values of individual n-alkanes. That the distributions of the n-alkanes showed bimodal and trimodal patterns, suggesting that they were derived from multiple sources. The long-chain n-alkanes were mainly derived from higher terrestrial plants. Those of odd carbon number (C₂₅~C₃₃) were lighter than those with even carbon number, which might be caused by different biosynthetic pathways. Cluster analysis indicated that the medium-chain type I n-alkanes (C₂₁~C₂₄) were mainly derived from higher terrestrial plants, and the medium-chain type Ⅱ n-alkanes might have originated from microorganisms such as bacteria. The medium-chain n-alkane δD values of samples FHS-10, TG2-10and TG3-10were the lightest, due to both the light δD values of water and bacteria or other microorganisms.