中文摘要：

通过测定纳木错现代植物和表层沉积物样品中的正构烷烃，结合主成分分析方法，明确了表层沉积物中烷烃的主要来源，并初步分析了它们在湖泊中的空间分布特征．研究结果显示，沉水植物所含烷烃以n-C21-C25为主，具有n-C23的峰值；陆生植物主要含n-C27-C33烷烃，具有n—C29或n-C31的峰值；但垫状点地梅（Androsace tapere）和香柏（Sabina pingii）的主峰碳却是n—C33烷烃，这在以往研究中鲜有报道．在纳木错表层沉积物中，正构烷烃具有典型的n-C3，和n-C23双峰分布形式，来源于低等菌藻类、沉水植物以及陆生植物．其中碳数小于C20的短链烷烃主要来源于低等菌藻类，其空间分布均一，由低等菌藻类的浮游生活型所决定；长链烷烃主要来源于高等植物，含量从滨岸到湖中心逐渐减少，这与其在运移和沉积过程中受微生物的持续降解作用有关．此外，来源于陆生植物的n-C27-C33烷烃因河流汇水面积和流量不同而存在空间差异，这值得重视和进一步研究．

英文摘要：

Aquatic and land plants as well as surface sediments from Nam Co in Tibetan Plateau were collected and n-alkanes analysis had been conducted to identify the sources and spatial distribution of these molecular. The results indicated that n-alkanes ranging from 21 to 25 were identified to be derived from submerged plants, while n-alkanes ranging from 27 to 33 with n-C29 or n-C31 peak were derived from land plants except Androsace tapete and Sabina pingii. These two species contain n-alkanes with n-C33 peak which were seldom reported before. Combined with information on plant sources and principal component analyses, three distinct groups of n-alkanes with different spatial distribution in surface sediments were defined. Short-chain n-alkanes derived from photosynthetic bacteria and algae were relatively uniform in whole lake. But concentration of long chain n-alkanes gradually reduce from lake shore to center coincided with transport distance increasing, indicating the main controlling mechanism of spatial distributions in surface sediments was connected with biodegradation.