中文摘要：

由于现代木本、草本植物正构烷烃主峰分布的研究结果存在一定的差异，从而导致黄土沉积中利用正构烷烃主峰分布进行古植被恢复时存在较大争议，尤其是松科植物主峰分布的不同。因此，采集黄土高原西部地区常见木本和草本植物及其表土，包括研究区常见松科植物，利用GC分析，开展现代植物及其表土正构烷烃主峰分布的研究。结果发现，黄土高原西部地区常见10种木本植物正构烷烃的主峰分布均以C27或C29为主峰，3种草本植物以C31为主峰，与分子有机地球化学研究结果一致，研究区3种常见松科植物均以C29为主峰，并无C31为主峰的分布；研究区现代表土正构烷烃的结果显示，表土正构烷烃主峰分布与上覆植被输入量有直接关系，对于不同景观的采样点，由于其木本、草本植物输入量的差异而导致正构烷烃分布存在差异，对于有机质来源较为多元化的地区，分析要十分慎重。同一种植物腐叶与新鲜叶片正构烷烃主峰分布是一致的，说明植物叶片的腐烂过程对其正构烷烃主峰分布没有产生影响。对同一种植物不同地区的对比分析发现，木本植物正构烷烃主峰分布特征受生长环境影响较小，主峰分布不变，但是对于草本植物受生长环境影响较大，主峰分布会产生变化。因此，对于黄土沉积中利用正构烷烃主峰分布特征进行的古植被恢复在开展现代过程研究的基础上是较为可靠准确的。

英文摘要：

Many studies show that n-alkane distribution from different modern vegetation are very different, and it is still a hot debate about using the n-alkane distribution to reconstruct the paleovegetation in loess deposition,especially the n-alkane distribution of conifer. We collected familiar some vegetation and surface soil in the Western Loess Plateau,including 3 kinds of conifer, and analysed by GC for the distribution model of n-alkanes. The results revealed that 10 kinds of wood vegetation showed heavy-molecular-weight （HMW）homologues of the n-alkanes distribution with the main peak of C27 or C29 ,while in 3 kinds of herb n-alkanes,the HMW homologues distributions of C31 or C33 are the main peaks,which show a completely different distribution feature from woody plants. The 3 kinds of conifer are typical of wood plants with the main peak of C29 without C31 main peak. The n-alkanes distribution in the modern surface soil was directly related to the quantity of the input of the vegetation. For different sites, wood vegetation and the herb vegetation had different input, so there are different n-alkanes distributions in the associated surface soils. The distributions of n-alkane from decomposed leaf and fresh leaf have same main peaks, indicating the leaf decay does not have significant impact on the main peaks. In this research area the same wood plant in different site showed the same main peaks of n-alkane,but the herb plant showed different. The growth environment will affect the main peaks of n-alkane of herb plant,but not for the wood plants. Depend on the research of modern vegetation and surface soil, therefore, the main peaks of n-alkane in loess sediments could be comparatively reliable in palaovegetation recunstructions.