【摘要】 为了解高原地区湿润气候-淡水湖环境中植物正构烷烃及其氢同位素组成,应用色谱-质谱联用仪(GC-MS)和气相色谱-高温热转变-同位素比值质谱议(GC-TC-IRMS),分析了甘南尕海湖泊和周围地区植物中正构烷烃及其氢同位素组成特征.结果表明:植物中正构烷烃主要由中等和长链组分组成(C21~C37),具有较强的奇偶优势;平均碳链长度(ACL值)与主峰碳数呈正相关趋势,与Qw=(C27+C29)/(C27+C29+C31)呈负相关趋势;植物中正构烷烃平均δD值分布在-246.5‰~-130.3‰之间,并且整体上是木本植物较高,草本植物较低,水生植物介于它们之间;植物种类、叶面积、水源和气候环境都影响了植物正构烷烃氢同位素组成;δD值随ACL值增加具有变低的趋势,随着Qw值增加具有变高的趋势;氢同位素分馏效应呈现为草本植物大,木本植物小,水生植物介于它们之间.更多还原

【Abstract】 In order to understand the compositional features of the plant n-alkanes and theirδD values for the plateau humid climate-freshwater lake system,the distributions of n-alkanes and their hydrogen isotopic compositions in plants from Gannan Gahai Lake and the surrounding area were for the first time investigated by GC-MS and GC-TC-IRMS analyses.The results showed that n-alkanes in the plants are composed mainly of the medium-and long-chain homologues(C21—C37),and are dominated by odd carbon-numbered components.The average chain length(ACL)values of n-alkanes were correlated with main peak carbon number,and negatively correlated with Qw=(C27+C29)/(C27+C29+C31)values.The meanδD values of n-alkanes range in-246.5‰—-130.3‰.As a whole,n-alkaneδD values were higher for woody plants,lower for herbaceous plants,and between them for aquatic plants.The results showed that the hydrogen isotopic composition of n-alkanes in the plants was influenced by plant species,area size of plant leaves,water source and climate environment.TheδD values of n-alkanes tend to be lower with increasing ACLvalues and lighter with increasing Qwvalues.Thehydrogen isotope fractionation effect is bigger for herbaceous plants,smaller for woody plants and between them for aquatic plants.更多还原