祁连山水合物分布区不同高寒生态类型冬季表层土壤中古菌群落及变化特征
Winter Seasonal Characteristics of the Archaeal Communities in Different Alpine Ecosystem Topsoils Collected from the Gas Hydrate Drilling Area，Qilian Mountains

摘要： 祁连山冻土区是我国青藏高原重要永久冻土区之一，也是我国陆域天然气水合物分布的重要地区。前期调查表明祁连山木里天然气水合物钻井区一带具 有丰富多样的高寒冻土生态类型。为了解该地区高寒草甸和高寒沼泽草甸表层土壤中古菌群落的多样性及分布特征，对2014年初冬在该区采集的表层土壤样品利用16S rRNA分子生物学技术和 地球化学等方法进行了分析和研究。结果显示，高寒草甸区土壤呈中性，而高寒沼泽草甸区土壤呈弱酸性。钻井区土壤中的TOC和顶空气甲烷含量均显著高于背景区，而在背景区内的两种生态 类型土壤中的TOC和顶空气甲烷含量差别较小。钻井区(除1个点)微生物细胞丰度高于背景区2~5倍。冬季表层土壤中的古菌多样性较低，含泉古菌的3个类群和广古菌的3个类群。不同植被类型 古菌群落的优势种群显著不同，在高寒草甸区为泉古菌门的Group Ⅰ.1b，而高寒沼泽草甸区为广古菌门的甲烷八叠球菌目(Methanosarcinales)。根据研究结果推测，土壤水分可能是导致高 寒草甸区和高寒沼泽草甸区细胞丰度和古菌群落差异的一个主要原因，高寒沼泽草甸区内产甲烷菌占优势可能与土壤高TOC含量有关。高寒沼泽草甸土壤中存在较丰富的产甲烷古菌，它们在厌 氧条件下的甲烷氧化作用也是土壤中甲烷来源之一。
Abstract: Qilian Mountain Permafrost，located in the north of Tibet Plateau, is one of the most important permafrost regions, and it is also known as an important area for gas hydrate distribution on land in China. Previous studies showed that two main types of alpine ecosystems, including alpine meadow and alpine swamp meadow, were observed around the gas hydrate drilling area. In order to insight into the archaeal community and its distribution in the both topsoils of alpine ecosystem, the geochemical parameters and archaeal community compositions were analyzed for the soil samples collected during the early winter of 2014. The results showed that pH of the soils from alpine meadow were neutral, whereas pH of the soils from alpine swamp meadow were slightly acidic. The TOC content and methane concentration in the soils of the drilling area were significantly higher than those in the background area (non-hydrate drilling area), however, they were shown no difference when compared with those in different topsoils of alpine ecosystems in background area. The microbial cell abundance in the drilling area (except for DZ2-14Q-5T sample) was 2 to 5 folds higher than that in the background area. The archaeal biodiversity was poor in the winter seasonal topsoils, and was comprised of three archaeal groups affiliated to Crenarchaeota and three groups affiliated to Eurarchaeota. The archaeal communities from alpine meadow topsoils were dominated by Group Ⅰ.1b affiliated to Crenarchaeota, while alpine swamp meadow topsoils were dominated by Methanosarcinales affiliated to Eurarchaeota.It was inferred that the moisture in topsoils may be one of the most important reasons causing the variation of microbial cell abundances and the different compositions of archaeal communities between the both topsoils of alpine ecosystem, and the methanogenic archaea dominated in the alpine swap meadow soils was more related to the higher TOC content. The results also showed that more abundance of methanogenic archaea inhabited in the