海底冷泉系统硫的生物地球化学过程及其沉积记录研究进展

Progress on the Biogeochemical Process of Sulfur and Its Geological Record at Submarine Cold Seeps

地球表层甲烷的迁移转化与气候变化、全球碳硫循环、海底生态环境等密切相关。现代海底冷泉是典型的富甲烷环境,冷泉系统中与甲烷厌氧氧化耦合的微生物硫酸盐还原作用(AOM-MSR)是甲烷最主要的消耗方式。该过程导致了孔隙水地球化学特征的变化,并最终以元素含量和同位素异常的形式记录在相应的自生矿物(黄铁矿、碳酸盐、重晶石)等载体中。因此,冷泉系统中硫的生物地球化学过程及其沉积记录的研究为探究甲烷在地球表层环境演化中的角色奠定了基础。本文围绕冷泉系统中硫的生物地球化学过程,综述了其在确定甲烷渗漏通量和识别古冷泉活动(富甲烷环境)等研究中的进展,重点阐述了在这些研究方向中应用“高维”稳定同位素(32 S/33 S/34 S/16 O/18 O)所取得的突破性成果。目前已经建立了识别地质历史时期富甲烷环境的方法体系,但其在地史研究中的应用尚在起步阶段。同时,未来应开展富甲烷环境中碳硫循环与环境效应具体关联及其沉积记录的深入研究,以期深化对甲烷在调节地球环境和气候变化中的作用等重大科学研究中的认识。

The migration and transformation of methane in the Earth's surface play an important role in regulating climate change,global carbon and sulfur cycles,and marine ecological environment.Modern marine cold hydrocarbon seep is a typical methane-rich environment,where methane is consumed mostly by the anaerobic oxidation of methane coupled with the microbial sulfate reduction(AOM-MSR).Such processes might lead the geochemical anomaly of pore water and eventually be archived in sedimentary records.Therefore,the study of biogeochemical processes of sulfur in the submarine cold-seep system and their sedimentary records has laid a foundation for exploring the role of methane in the evolution of the earth's surface environment.This review focuses on the biogeochemical process of sulfur in the cold-seep system,and summarizes the research advances in determining methane leakage flux and in identifying ancient cold-seeps activities(methane-rich environment),especially the breakthrough for the application of"high-dimensional"stable isotopes(32 S/33 S/34 S/16 O/18 O).A methodology system has been established to identify the methane-rich environment in sedimentary records,but its applications in the geological history research are still scarce.Further researches on specific correlations between carbon and sulfur cycles in methane-rich environments,as well as their environmental effects and sedimentary records,are much required to comprehensively understand the role of methane in regulating the change of the Earth's environment and climate.