南海北部天然气水合物潜在区973-3岩心古菌多样性  

Archaeal diversity analyses of core 973-3 from potential gas hydrate area in northern South China Sea

作　　者：杨玉峰[1,2] 雷怀彦[1,2] 史春潇 

机构地区：[1]厦门大学近海海洋环境科学国家重点实验室,福建厦门361102 [2]厦门大学海洋与地球学院,福建厦门361102

出　　处：《石油与天然气地质》2016年第3期415-421,共7页Oil & Gas Geology

基　　金：国家自然科学基金项目(41276046)

摘　　要：海底微生物产甲烷和甲烷厌氧氧化作用对全球甲烷循环有着重要影响。在全球升温的背景下，海底天然气水合物作为地球上的一个巨大甲烷库，具有重要的环境效应。利用基于16SrDNA的分子生物学技术，对南海北部台西南盆地天然气水合物潜在区沉积物中古菌多样性进行了分析，探讨了成岩环境因素对古菌种群分布的影响。结果显示：在973—3岩心20—450cm深度段，Methanosaeta为优势菌群，所占比例为32．9％；Methanosarcinales在542—870cm深度段所占比例最高，达到28．3％；Methanomicrobia—zes在1075—1162cm深度段所占比例高达20．7％。973—3岩心古菌种群分布与甲烷产生、氧化密切相关，预示其下部赋存天然气水合物。973—3岩心成岩环境参数垂向变异与天然气水合物成藏有着明显响应关系：pH值随岩心深度增加而变大，Eh（氧化还原电位）值、盐度和沉积物粒径的变化趋势则相反。973—3岩心与日本海、南海神狐海域等天然气水合物赋存区、非赋存区古菌群落结构明显不同，这是由于pH值、Eh值和沉积物粒径等成岩环境参数对973—3岩心古菌种群分布有着显著影响，故必须深入研究微生物代谢甲烷活动的生态位，以提高古菌群落结构对天然气水合物的指示性。Methanogenesis and anaerobic oxidation of methane driven by microbial activites are important for the global methane cycle. Marine gas hydrate is a huge methane reservoir on Earth, however, it remains unclear whether archaeal community structure in marine sediments can indicate marine gas hydrate. In this study, distinct archaeal communities thriving in marine sediments of core 973-3 in southwestern Taiwan Basin of the northern South China Sea were characte- rized by 16S rDNA gene analysis. Moreover,we discussed the effect of diagenetic environment factors on archaeal commu- nity distributions. Results show that Methanosaeta is the most abundant in 20 -450 cm depths, with 32. 9 % proportion. Methanosarcinales dominates in 542-870cm depths with 28.3 % proportion, while Methanomicrobiales is predominant in 1 075-1 162cm depths with 20.7 % proportion. The archaeal community structure in core 973-3 is closely related to the methanogenesis and methane oxidation, indicating the presence of gas hydrate. The variations of diagenetic environment parameters are responding to the gas hydrate formation. The pH values increase with depth, contrary to Eh, salinity and grain sizes. It is obviously different of archaeal communities in core 973-3, compared to that in gas hydrate-containing and -free sediments from Japan Sea and the Shenhu area of South China Sea, owing to the significant effects of pH, Eh and grain sizes on the distributions of archaeal community in core 973-3. Hence, it is essential to focus on the main niche for the methanogens and methanotrophs, to improve archaeal communities indicating marine gas hydrate.

关 键 词：古菌多样性 成岩环境 天然气水合物 台西南盆地 南海北部 

分 类 号：TE132.2[石油与天然气工程—油气勘探]