硫酸盐细菌还原是全球碳循环和硫循环的重要组成部分，利用硫酸盐δ34S，δ18O，Δ33S可以进行硫酸盐细菌还原机理和总硫酸盐还原速率的研究。硫酸盐细菌还原包括OSR与AOM-SR两个过程，由于两过程细胞内新陈代谢路径的差异，δ34S，δ18O，Δ33S也可以用于AOM-SR过程的识别和甲烷通量评估。本研究拟以南海北部陆坡不同地质背景下的沉积物孔隙水作为研究对象，利用孔隙水δ34S，δ18O，Δ33S开展硫酸盐还原速率评估、AOM-SR过程识别、甲烷通量估算以及硫再循环示踪等工作，将得到的结果和利用传统办法得到的相应结果进行对比，评估其在自然环境下的应用价值，分析不同环境因素对硫酸盐还原过程的影响，为δ34S，δ18O，Δ33S在自然环境下对硫酸盐还原的应用研究提供依据。

In modern oceans, sulfate reduction occur within pore water below the sediments-water interface. This process has important implications in many aspects regarding global carbon cycle, climate change, paleo-ocean study and gas hydrate exploration. Bacterial sulfate reduction involves several intracellular metabolic steps; and the δ34S，δ18O，Δ33S values in remaining sulfate depends on the isotope partitioning during each of the intercellular steps and on the ratio between the backward and forward sulfur fluxes within the bacterial cells. As a result, δ34S，δ18O，Δ33S in sulfate can be used to investigate the mechanism and rate for sulfate reduction. Both OSR Organiclastic Sulfate Reduction（OSR） and sulfate couple to anaerobic oxidation of methane（AOM-SR） process are known to reduce sulfate to sulfide, but the specific pathways for the two processes differ greatly. The three indexes can be used for the identification of AOM-SR process and evaluation of methane flux. To date, the study of how δ34S，δ18O，Δ33S in sulfate vary during sulfate reduction has mostly performed in labs, yet how these indexes would response to more complex natural environments remains uncertain.The northern slope in the South China Sea represents a well-studied area in terms of pore water investigations. We plan to carry out δ34S，δ18O，Δ33S analysis for pore waters in sites with different sedimentary backgrounds in this region, with the aim to evaluate the sulfate reduction rate, to identify AOM-SR process and to estimate the methane fluxes. The obtaining results, combined with results based on traditional methods, will be used to evaluate how environmental factors affect these indexes, and provide further information for their implications in natural environment.