中文摘要：

以小球藻（Chlorela sp．）和三角褐指藻（Phaeodactylum tricornutum）为研究对象，比较了其合成有机物中长链烷烃和脂肪酸的组成和丰度。结果表明，小球藻中的脂肪酸以14：0、16：1、16：0、20：5为主，其中16：0饱和脂肪酸的质量分数为43％，具绝对优势。三角褐指藻中的脂肪酸组成显示16：1、16：0、20：5占优势。其中16：1和16：0两种脂肪酸含量相当。长链烷烃在两种藻中均以低碳链分布，优势组分集中在C16～C21碳链之间。小球藻中C17具有明显丰度，而三角褐指藻中长链烷烃含量差别不大。两种微藻中的长链烷烃组成都没有奇偶优势碳链分布的特征，这与陆源植物中长链烷烃明显的奇偶优势分布特征相比，具有显著的差异。这些结果对判断不同微藻在食物链中的营养级别，以及对以长链烷烃和脂肪酸为生物标志物研究我国近岸海沉积物中有机物的来源均具有实际意义。

英文摘要：

The compositions and abundances of fatty acids and n-alkanes were measured for two marine phytoplanktons Chlorella sp. and Phaeodactylum tricornutum. Our results indicate that the short chain saturated and monosaturated fatty acids, 14 ： 0, 16 ： 0, 16 ： 1 comprised major fraction of the detected fatty acids in the two algae species. In addition, 18：0, 18：1 and 20：5 also showed relatively high abundances in Chlorella sp. and 20：5 in P. tricornutum. Compared with fatty acids, the abundance of n-alkanes was much lower in the two algae species and was predominated by the short chain C16-C23 compounds. The composition and distribution characteristics of fatty acid and n-alkanes in Chlorella sp. and P. tricornutum could play certain roles in their ecological significance. Our results also confirm the efficiency of using fatty acids and n-alkanes as biomarkers to distinguish organic matter sources in marine sediments.