海底含甲烷冷泉流体渗漏过程中微生物作用及对碳硫循环的影响

冷泉是指来自海底沉积地层的流体以喷涌或渗漏的方式注入海水中的地质现象。在海底沉积层相关微生物作用下，冷泉流体中甲烷的碳和海水中的硫被转化，以自生矿物的形式被固定在沉积物中，影响着海洋中碳、硫元素的循环过程。本研究以我国南海北部珠江口盆地白云凹陷的地质及生物地球化学条件为背景，围绕着“含甲烷流体-微生物-沉积物相互作用和碳、硫循环”等科学问题，采用资料搜集分析、室内实验、数值模拟和现场考察相结合的技术手段，研究冷泉流体渗漏过程中甲烷-微生物-水（孔隙水、海水）-沉积物之间的相互作用，阐明微生物的作用机理，揭示碳、硫循环机制；构建甲烷流体运移过程及生物地球化学响应的数值模型，定量研究微生物行为及其对海底碳、硫循环的影响。项目研究成果不但有助于科学认识和评价海洋过程在全球气候变化中的潜在影响及作用机理，同时还可以为寻找海底甲烷水合物、油气和矿产资源提供基础理论依据。

Cold seep is a geological phenomenon in which the fluid from the shallow marine sediments is injected into seawater bottom by spewing or leaking. Under the action of related microorganisms, the carbon of methane from the cold seeps and the sulfur from the seawater are fixed in the sediments as authigenic minerals, which significantly influences the cycles of carbon and sulfur in the ocean. Based on the geological and biogeochemical conditions of the Baiyun Sag in Pearl River Mouth Basin, Northern Slope of South China Sea, by the means of data collection and analyses, laboratory experiment and numerical simulation, focusing on the key scientific issues: “the methane-bearing fluid-microorganism-sediment interaction, carbon and sulfur cycles”, this project proposes to investigate the interactions among methane, microorganism, water (pore water, seawater), and sediment; to elucidate the mechanism of microbial action, to reveal the cycling mechanism of carbon and sulfur; to build numerical models for describing the methane-bearing fluid flow and the associated biogeochemical responses. Finally, the behavior of microorganism and its effects on the carbon and sulfur cycles are quantitatively investigated. The research results generated from this study are not only helpful for understanding the action mechanism of oceanic processes and assessing its potential impacts on the global climate change, but also are able to provide theoretical basis for exploring marine methane hydrate, oil and gas and mineral resources.