摘要
陆架边缘海沉积物是重要的生物地球化学反应器,海洋中90%以上的有机质沉积于此并在早期成岩作用过程中矿化。其矿化路径包括有氧呼吸、反硝化、锰氧化物还原、铁氧化物还原、SO42-还原和CO2还原,并按生成自由能减少的顺序依次发生,构成理想的氧化还原序列。定量研究有机碳矿化路径及其对有机质矿化的相对贡献对揭示能量分配和碳循环具有重要的生态学和环境学意义,也是揭示铁、硫、磷及许多氧化还原敏感性微量组分生物地球化学循环的基础。介绍了海洋沉积物中有机质早期成岩矿化路径的主要特点及不同路径对有机质矿化的相对贡献,重点阐述了长期被忽略的铁锰氧化物异化还原路径的研究进展。总体而言,在远洋深海沉积物中,有氧呼吸是有机质矿化唯一的重要路径;而近海沉积物中,铁异化还原和SO42-还原是最主要的厌氧矿化路径,其中SO42-还原占(62±17)%。从远洋深海到近海陆架,沉积物中有氧呼吸和SO42-还原对有机质矿化的相对贡献具侧向分带特征。最近的反应—传输模拟表明,在全球尺度上,有氧呼吸、反硝化、铁异化还原以及SO42-还原对有机质矿化的相对贡献分别为15%、6.2%、2.8%和76%。
Continental margin sediments are an important biogeochemical reactor,where 90% of organic matter（OM） is deposited and remineralized.OM remineralization proceeds from the use of O2,NO-3,Mn（IV）-oxides,Fe（III）-oxides,sulfate,and finally CO2 according to the gains of free energy yield,forming an ideal redox sequence.Differentiating various diagenetic pathways and their relative contributions to OM remineralization is of ecological importance for understanding energy partitioning and carbon cycling,and of biogeochemical importance for understanding the cycling of iron,sulfur,phosphorus,and redox-sensitive trace compounds.The main characteristics of diagenetic pathways of OM degradation and their relative contributions,particularly dissimilatory reduction of Fe（III）-and Mn（IV）-oxides,are reviewed.Generally,in pelagic deep sediments,aerobic respiration is the only important pathway for OM degradation;in continental margin sediments,however,anaerobic pathways coupled to dissimilatory reduction of Fe（III）-oxides and sulfate are mainly responsible for OM degradation,with sulfate reduction accounting for averagely（62±17）%.From pelagic deep-sea to continental margin sediments,lateral zonation of the relative contributions of aerobic respiration and sulfate reduction,respectively,to carbon mineralization can be observed.Recent reaction-transport modeling indicates that global-scale contributions of aerobic respiration,denitrification,dissimilatory Fe（III） reduction,and sulfate reduction to OM degradation are 15%,6.2%,2.8%,and 76%,respectively.
出处
《地球科学进展》
CAS
CSCD
北大核心
2011年第4期355-364,共10页
Advances in Earth Science
基金
海洋沉积与环境地质国家海洋局重点实验室开放基金项目“受富营养化影响的沉积物中硫早期成岩循环及黄铁矿积累研究”(编号:MASEG200811)
国家自然科学基金项目“中国东海典型边缘海沉积物中硫的早期成岩循环及制约因素”(编号:41076045)和“中国东海和黄海中生源硫的生产、分布、迁移转化与环境效应”(编号:41030858)
教育部留学回国人员科研启动基金项目“受富营养化影响的胶州湾沉积物硫酸盐还原速率(SRR)研究”资助
关键词
早期成岩作用
海洋沉积物
矿化路径
有机质
Early diagenesis
Marine sediment
Remineralization pathways
Organic matter
