海底地震驱动下海沟深渊有机碳的输入、转化与封存

本项目核心研究内容是利用西太平洋海沟沉积记录开展碳元素循环与通量研究，属于重大研究计划本年度重点研究内容之第五项。海沟深渊碳循环是深海科学国际前沿领域，是研究深海多圈层物质循环的重要着力点。本项目围绕“海沟深渊碳循环”这一核心主题，以西太平洋日本海沟为研究区，探究在海底地震诱发浊流沉积的背景下海沟有机碳的输入、转化与封存等碳循环重要科学问题。本项目将利用多学科交叉优势，采用先进的单体分子碳-14技术、基因测序、有机碳热分解、纳米微区分析等方法，重点解决三项科学问题：1) 厘清地震触发的浊流沉积在长时间尺度下输送到海沟深渊的有机碳的类型、碳源和通量；2) 探究浊流沉积对海沟微生物利用转化有机碳的影响与控制因素；3) 估算经历漫长地质历史时间封存（指不再参与循环回到地球表层）在俯冲带的海沟有机碳的通量。本项目是深海科学前瞻性基础研究，将为推动我国深海圈层与地球系统科学理论发展提供重要支撑。

The key objective of this project is to investigate the carbon cycles and fluxes in the hadal sediments of the West Pacific Ocean, coinciding the No. 5 article of Guide to Program 2020 for Major Research Plan on West-Pacific Earth Multispheric Interactions. The Deep-ocean carbon cycles in the hadal sediments, as a cutting-edge research, constitute a key scientific frontier in investigating deep-ocean biogeo-spheric biogeochemical cycles and systematic earth sciences. Centering on the carbon cycles in the hadal zone, this project will investigate the export, transfer, and burial of sedimentary organic carbon in the Japan Trench in the context of frequent occurrences of submarine earthquakes, using cross-disciplinary approaches (e.g., compound specific radiocarbon analysis, DNA sequencing, ramped pyrolysis, computed tomography, nanoSIMS etc.). There are three key scientific questions in this project: 1) identifying the organic carbon in the downcore sediments and surface sediments exported with turbidites triggered by the submarine earthquakes along the trench axis, examining and quantifying the fluxes and sources of organic carbon; 2) exploring the influences of turbidites triggered by the earthquakes in the communities and metabolisms of hadal microbes fueling the exported organic carbon; 3) evaluating the burial fluxes of hadal organic carbon exported downward the subduction slab, as well as its significance in the global marine organic carbon cycles. This would be a promising and frontier project in deep ocean sciences, advancing a fundamental development of the Chinese studies for deep-ocean-spheres and systematic earth sciences.