南海北部甲烷渗漏区沉积物铁锰的生物地球化学循环模式研究

铁锰既可参与构成微生物细胞，又可在胞外作为电子受体支配微生物呼吸和代谢，铁锰埋藏下来以后，在厌氧环境中的氧化还原很大程度受微生物转化及酶促反应控制，影响其生物地球化学循环的主要有有机质矿化和甲烷厌氧氧化两类微生物作用，尤其在甲烷渗漏区，甲烷厌氧氧化作用使得铁锰的赋存形态、含量以及自生矿物的类型和分布都发生显著改变。因此，本项目选择我国南海北部甲烷渗漏区，以铁锰还原偶联甲烷厌氧氧化反应为切入点，采用传统微生物培养结合分子生物学技术，查明甲烷厌氧氧化反应中铁锰的参与机理，揭示微生物的作用机制，建立不同电子受体、甲烷通量的甲烷厌氧氧化微生物模型；同时，通过对沉积物中铁锰元素不同赋存形态及其自生矿物在垂向分布的定性以及定量的系统研究，结合甲烷厌氧氧化反应机理，建立铁锰生物地球化学循环的数值模型和理论模式，研究其与下伏地层甲烷通量以及来源的关系，并将此模型和判识指标应用于海底油气和甲烷水合物藏找矿。

Iron and manganese were the part of the enzymes and cofactors in the cell of microorganisms, they played an important role in the cell metabolism, so when they buried in the ocean sediments, their redox was controlled by the bio. transform and enzyme reaction. There were two processes: the dissimilatory Fe(III) and Mn(IV) reduction coupled the mineralization of organic matter and the Fe(III)- and Mn(IV)-dependent anaerobic oxidation of methane, could be the factors that influence the iron and manganese biogeochemical cycling in marine sediments, especially in the methane-seep sediments, the geochemical characteristics of the Fe and Mn and their authigenic minerals would be changed. So we propose to investigate what role that the microorganisms played in the anaerobic oxidation of methane and what role that the Fe and Mn played in the process by pure culture and molecular techniques. The reaction rate in different methane pressure will be tested, and the model of the geochemical data that come from the different iron and manganese’s occurrence mode in the methane-seep sediments in the northern of the South China Sea will be built. After all these works, we will get the biogeochemical cycling model of iron and manganese. And all these models and theories will be used a lot more in oceanography, and have a great value of practical application in oil and gas and methane gas hydrate exploration.