西藏纳木错表层沉积物中正构烷烃的来源与空间分布特征  

Sources and spatial distribution character of n-alkanes in surface sediments of Nam Co on the Tibetan Plateau

作　　者：林晓[1,2] 朱立平[2] 王君波[2] 汪勇[2,3] 甄晓林[2,3] 鞠建廷 谢曼平[2,3] 彭萍[2,3] 

机构地区：[1]中国地质大学生物地质与环境地质教育部重点实验室,武汉430074 [2]中国科学院青藏高原研究所,北京100085 [3]中国科学院研究生院,北京100049 [4]<中国科学>杂志社,北京100717

出　　处：《湖泊科学》2009年第5期654-662,共9页Journal of Lake Sciences

基　　金：国家重点基础研究发展计划项目(2005CB422002);国家自然科学基金项目(40701194);中国地质大学(武汉)优秀青年教师计划(CUGQNL0927)

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 tapete)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-C31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.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.

关 键 词：表层沉积物 正构烷烃 空间分布 纳木错 青藏高原 

分 类 号：P593[天文地球—地球化学]