中文摘要：

开展了自长白山至贝加尔湖空间跨度约2000 km断面上代表性地点的水生植物正构烷烃及其单体氢同位素研究.结果表明,该区域大型水生植物正构烷烃具有明显的奇偶优势,以C23或C25为主峰,这两个链长的正构烷烃可以作为研究区水生植物来源的普适性特征标志物.同一植物来源的不同链长正构烷烃的单体氢同位素值相近,尤其是n-C21,n-C23,n-C25三者的氢同位素值相差很小.水生植物正构烷烃与环境水间的氢同位素分馏值稳定在？159‰左右,与欧洲等地区获得的结果有很好的一致性,表明正构烷烃单体氢同位素可以示踪水体的氢同位素组成.全球水生植物正构烷烃氢同位素数据综合分析显示,正构烷烃C23和C25氢同位素平均值是反演环境水体氢同位素组成的优选代用指标.本研究不仅获得了这一区域水生植物的分子标志物数据,同时对全面认识和理解正构烷烃氢同位素组成及其在古气候研究中的应用具有重要意义.

英文摘要：

With the advance of gas chromatography/thermal conversion isotope ration mass spectrometry（GC/TC/IRMS）, compound-specific hydrogen isotope composition（δD） of molecular organic markers is increasingly used as a palaeoclimate proxy. To explore the hydrogen isotopic fractionation relationships between the alkanes derived from aquatic plants in lakes and the lake waters, we have investigated n-alkane distributions and their δD values of the aquatic plants collected from 5 typical lakes on the Changbai Mountains-Lake Baikal transect in the northern East Asian monsoon regime. The n-C23 and/or n-C25 alkanes are the dominant compounds in submerged aquatic plants. The average chain length（ACL） and the P aq values range from 22.7–26.3 and 0.5–0.99, respectively. δD values of different n-alkanes from a single plant are similar, especially for the n-C21, n-C23 and n-C25. The mean apparent hydrogen isotope fractionation between the lacustrine aquatic plant alkanes and lake waters is -159‰ for the study area, consistent with the conclusion obtained from a European transect（-160‰）. We suggest that n-alkanes from aquatic plants can be used to trace the hydrogen isotope composition of the environmental water. On a global scaled basis, the average δD values of n-C23 and n-C25 alkanes might be an optimized proxy with great potential in paleoenvironmental study.