中国南海IODP349航次深部沉积物孔隙水的生物地球化学的研究

项目名称： 中国南海IODP349航次深部沉积物孔隙水的生物地球化学的研究

项目编号： No.91428102

项目类型： 重大研究计划

立项/批准年度： 2015

项目学科： 地球化学

项目作者： 陈毅凤

作者单位： 中国科学院广州地球化学研究所

项目金额： 100万元

中文摘要： 海底沉积物孔隙水是海洋生物地球化学研究的核心内容。刚刚完成的中国南海IDOP349航次在水深达3829-4390米的深海海盆，成功采集了东部次海盆站位U1431的550米以浅的、陆/洋壳边界钻孔U1432C的110米以浅的和西南次海盆站位U1433的 588米以浅的高分辨率的孔隙水样品。“决心号”上的初步研究显示， U1432C和U1433含有较高浓度的甲烷，而U1431的基本无甲烷，站位间孔隙水的地球化学差异较大。因此本项目拟对3个站位的孔隙水和相对应的沉积物展开系统的地球化学分析测定，尤其是孔隙水的DIC、DOC和乙酸浓度，以及DIC的δ13C，以及沉积物TIC的δ13C。揭示南海深部沉积物的生物地球化学过程和演化，及其与深部沉积系统碳循环的关联，探讨高浓度甲烷的可能来源和产生机制，探索它们与南海构造活动、沉积演化的关联。研究成果对深入认识全球远洋海底深部碳循环具有重要意义。

中文关键词： 孔隙水；DIC的碳稳定同位素；甲烷；生物地球化学过程；中国南海

英文摘要： Pore-water analysis is a central approach in marine biogeochemistry. During the recently accomplished IODP Expedition 349 in the South China Sea, high resolution pore-water samples were collected in subseafloor sediments of the East Sub-basin (Site U1431) to a depth of 550 mbsf (meters below seafloor), of the northern continent-ocean boundary (Hole U1432C) to a depth of 110 mbsf, and of Southwest Sub-basin (Site U1433) to a depth of 588 mbsf. Sites U1431, U1433 and Hole U1432C were drilled at water depths of 3289 to 4390 m. The preliminary results from onboard studies show that moderately high concentrations of methane occur at Site U1433 and Hole U1432C, but with background values of methane at Site U1431; and pore-water profiles of three sites are quite different from each other. Systematical geochemical analyses will be carried out, especially on DIC, DOC and acetate concentrations, and δ13C values of DIC in pore-waters, and δ13C values of TOC and TIC in sediments, to investigate the biogeochemical processes and their link with carbon cycling in deep subseafloor sediments in the South China Sea, and to determine the sources and methanogenesis of methane in U1432C and U1433, and to understand the impacts of the tectonics and sedimentary processes of the South China Sea on the biogeochemistry and carbon cycling in deep subseafloor sediments. This study will also provide a better understanding on the carbon cycling in deep subseafloor sediments in the global open oceans.

英文关键词： Pore water;δ13C of DIC;methane;biogeochemical processes;the South China Sea