冷泉碳酸盐岩有机碳、氮同位素的耦合及其对甲烷厌氧氧化过程的指示  

Coupling of organic carbon and nitrogen isotopes in cold seep carbonates and its implication for the anaerobic oxidation process of methane

作　　者：许卫校 胡钰 张东[1] 陈琳莹 冯东 陈多福[1] XU Wei-xiao;HU Yu;ZHANG Dong;CHEN Lin-ying;FENG Dong;CHEN Duo-fu(College of Oceanography and Ecological Science,Shanghai Ocean University,Shanghai 201306,China)

机构地区：[1]上海海洋大学海洋科学与生态环境学院,上海201306

出　　处：《矿物岩石地球化学通报》2024年第3期533-540,共8页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(42225603,42176056);上海市浦江人才计划项目(21PJ1404700)。

摘　　要：驱动甲烷厌氧氧化(AOM)过程的微生物不仅能同化吸收甲烷等碳氢化合物作为碳源,同时也能进行氮素的同化吸收,从而导致这些微生物的生物体出现显著的^(13)C、^(15)N亏损。目前还缺乏来自冷泉环境有机氮δ^(15)N数据来直接证实AOM参与氮的循环过程。本研究分析了来自墨西哥湾海底5个冷泉站位的自生碳酸盐岩的总氮(TN)、总无机氮(TIN)和总有机氮(TON)的含量及其δ^(15)N值,并结合前人获得的总无机碳和总有机碳含量和δ^(13)C数据进行研究,结果发现总氮的δ^(15)N与总有机碳的δ^(13)C只在部分站位表现出正相关性。然而,在排除无机氮的干扰后,总有机氮的δ^(15)N与总有机碳的δ^(13)C在所有站位均表现出正相关性。表明这种有机碳、氮同位素上的耦合与甲烷的活动密切相关,有望作为有效示踪过去海底甲烷渗漏及AOM作用的指标。The microorganisms that drive the anaerobic oxidation of methane(AOM)not only assimilate methane and other hydrocarbons as carbon sources,but also assimilate nitrogen,leading to the significant depletion of ^(13)C and ^(15)N in these microorganisms.However,there is still a lack of δ^(15)N data in cold seep environments to directly confirm the involvement of AOM in the nitrogen cycle process.In this study,we analyzed the contents of total nitrogen,total inorganic nitrogen and total organic nitrogen and their δ^(15)N in authigenic carbonate rocks from five cold seep sites on the Gulf of Mexico seafloor and compared them with the contents of total inorganic carbon and total organic carbon and δ^(13)C data obtained in previous studies.We found that the δ^(15)N of total nitrogen showed a positive correlation with the δ^(13)C of total organic carbon only at some of the sites.However,after excluding the interference of inorganic nitrogen,δ^(15)N of total organic nitrogen and δ^(13)C of total organic carbon showed positive correlation at all sites.Therefore,we propose that coupling of isotopes of organic carbon and organic nitrogen is closely related to methane seepages and is promising to serve as an effective indicator for tracing the past submarine methane seepages and AOM.

关 键 词：冷泉 自生碳酸盐岩 甲烷厌氧氧化 稳定碳同位素 稳定氮同位素 氮循环 

分 类 号：P595[天文地球—地球化学]