大河影响下的陆架边缘海沉积有机碳的再矿化作用

Remineralization of sedimentary organic carbon in river dominated ocean margins

大河影响下的陆架边缘海(RiOMars)是陆源有机碳的主要沉积汇,是陆海相互作用最重要的区域,在全球碳的生物地球化学循环中发挥着重要作用。受到RiOMars系统内频繁的物理和生物等改造作用的影响,该区沉积的有机碳并没有得到很好地保存而被永久埋藏,而是发生了显著的再矿化分解。本文首先对目前常用的基于O2消耗速率和CO2产生速率的两类测定RiOMars系统沉积有机碳再矿化速率的方法进行了介绍,分析了各自的优缺点和适用性,进而从碳的形态转化、表层沉积物混合均匀、形成次氧化的氧化还原条件、有机碳保存效率低、发生反风化作用和微生物发挥着重要作用等几个方面对RiOMars系统沉积物发生再矿化作用时的主要过程和特征进行了剖析,以期深入认识边缘海的再矿化作用及其对边缘海碳汇的影响。

River dominated ocean margins （RiOMars） are the major depocenter of terrestrial organic carbon and are recognized as the most important zone for land-sea interactions ,and play a very important role in global biogeo-chemical cycle of carbon .Effective remineralization of sedimentary organic carbon （SOC） occurs in these systems instead of efficient preservation and burial due to frequent physical and/or biological reworking of sediments in up-per layer .In this paper ,we introduced two kinds of commonly used methods for the determination of remineraliza-tion rate of SOC based on the consumption of O 2 and production of CO2 ,respectively .Advantages ,disadvantages and applicability of these methods were analyzed .In order to obtain a better understanding of the remineralization of SOC and its impact on carbon sink in continental margins ,major processes and characteristics of the remineral-ization of SOC in RiOMars were summarized into several aspects including transformation of carbon forms ,homo-geneous vertical distribution of surface sediments ,suboxic redox properties ,low preservation of organic carbon , occurrence of “reverse weathering”and high microbial biomass .