中文摘要：

基于南海北部陆坡不同深度梯度3个站位表层沉积物古菌氨单加氧酶基因（amo A）文库,对3个站位氨氧化古菌进行多样性和系统发育学分析。多种方法构建的系统发育树表明：3个站位所有的amo A基因序列都隶属于奇古菌门中Group I分枝内的Group I.1a系群,且各站位之间氨氧化古菌多样性没有明显的差异。501站位黑色砂质沉积物中古菌amo A基因与该站位的16S r RNA基因的系统发育比对显示：这2种基因标记的系统发育树整体上具有潜在的对应关系,说明对样品的氨氧化古菌多样性分析比较全面且可靠;并进一步暗示该样品中氨的硝化作用主要由奇古菌门下的Group I.1a系群来执行。由此可以推测：Group I.1a系群可能在南海北部表层沉积物中氮素的生物地球化学循环过程中扮演重要的角色。

英文摘要：

Surface sediment samples were taken from three sites of different water depths at the northern continental slope of the South China Sea to investigate the community structure of ammonia-oxidizing archaea（AOA）. Polymerase chain reaction（PCR） was employed to amplify the archaeal ammonia monooxygenase α subunit（amo A） gene of AOA. Amplicons of the amo A gene sequences were used to understand the diversity and phylogenetic relationship of AOA. The main results were as follows： 1） All of the archaeal amo A gene sequences from the three locations were affiliated to Group I.1a Thaumarchaeota; 2） all of the archaeal amo A gene sequences from the three locations were phylogenetically closely related; and 3） the 16 S r RNA gene and amo A gene phylogenetic trees were of congruent topology. Thaumarchaeota accounted for 40% of the total archaea, indicating that AOA might play an important role in the nitrogen biogeochemical cycling in the surface sediments of the northern continental slope of the South China Sea.