甲烷厌氧氧化作用（AOM）是与天然气水合物成藏相关的生物地球化学过程中最令人关注的科学问题，而甲烷厌氧氧化古菌（ANME）及其AOM机制对调控海底甲烷渗漏至关重要。然而，因很难获得海洋可培养的ANME，且其与共栖互养微生物之间的关系不能在实验室再现，故目前仍不清楚其能产生哪些专属性生物标志物，对AOM机制的认识仍为理论推测，尚未获得实验验证。对南海水合物成藏区沉积物柱中分子生物学的前期调研显示，在高通量甲烷渗漏地段甲烷氧化菌（MOB）与硫酸盐还原菌（SRB）的丰度呈现明显的依赖于深度的耦合关系，这种耦合关系前人未曾报道。本项目拟对沉积物柱中ANME与SRB相关的两类生物标志物及其碳同位素组成的垂向分布规律进行研究，通过与已知分子生物学证据对接，厘定AOM专属性生物标志物，并确证分子生物学证据所显示的多种AOM机制的空间叠置关系，进而为发展识别甲烷渗漏的有效标识和指导水合物勘探提供科学佐证。

Anaerobic oxidation of methane (AOM) is the most attractive biogeochemical process associated with the formation of gas hydrates. The anaerobic methane oxidation archaea (ANME) and their AOM mechanisms are critical to mediate the submarine methane seepage. However, because it is difficult to obtian ANME cultures in marine environments, and the relationship between ANME and their symbiotic mutual microbes cannot be reproduced in the laboratory, the specificity of lipid biomarkers for ANME remains unknown, and understanding the AOM mechanisms still stays in the theoretical speculation, and no experimental evidence is provided. Our previous molecular biology studies of one sediment core from the high methane-flux region in the hydrate accumulation area in the South China Sea show a depth-related coupling relation between methane-oxidizing bacteria (MOB) and sulfate-reducing bacteria (SRB), which has not reported previously. This project will focus on the vertical distribution of ANME and SRB related biomarkers and their carbon isotope composition in the same sediment column, aiming to determine the AOM specific biomarkers, and further confirm the spatial superimposed relationship of diverse AOM mechanisms in comparison with the known evidences in molecular biology. Our results will provide new evident to develop the effective indicators for discriminating methane seepage and guide the exploration of gas hydrates.