南海北部深海颗粒有机碳来源的时空变化研究

颗粒有机碳在深海的沉降和埋藏是海洋生物泵效率的最终体现，是海洋碳循环的关键组成部分。近期的研究显示，深海颗粒有机碳除了生物泵输出的海源有机碳之外，有相当一部分来源于陆源提供的土壤和岩石颗粒有机碳，而后者参与海洋碳循环的功能截然不同。因此，鉴别深海颗粒有机碳的海源和陆源性质及其变化，是科学评估颗粒有机碳沉降对海洋碳循环贡献的前提。本项目选择南海北部深海三个关键站位的沉积物捕集器时间序列颗粒物样品，运用先进的放射性碳-14测年技术，并辅以有机碳稳定同位素、总有机碳/总氮含量、硅酸盐矿物比表面积和粒度指标，分析南海北部深海颗粒有机碳的来源和通量及其与矿物间的关系，揭示海源和陆源颗粒有机碳的贡献及其在时间和空间序列上变化，探究颗粒有机碳在南海深海搬运过程中的降解和保存控制因素。通过本项研究，将有效提升陆源颗粒有机碳在深海尤其是边缘海碳循环作用中的认识，对理解海洋碳循环具有重要科学意义。

The settling and burial of particulate organic carbon (POC) in the deep sea reflect the efficiency of biological pump, and are a key component of ocean carbon cycle. Recent studies show that besides the marine organic carbon exported by the biological pump, a certain proportion of deep sea POC is derived from the continental soil and bedrock, whose functions are strongly differently in ocean carbon cycle. Therefore, distinguishing the marine and terrestrial sources of POC in deep sea and their variations is essential to scientifically evaluate the important role of POC settling in the ocean carbon cycle. This project intents to use the time-series particulate matter samples collected by sediment trap at three key sites in the deep northern South China Sea (SCS), and applies the state-of-the-art radiocarbon dating method, combined with the proxies of stable isotope of organic carbon, contents of total organic carbon and total nitrogen, surface area of silicate minerals, and grain size, in order to investigate the sources and fluxes of POC and their relationships with silicate minerals, reveal the contribution from marine and terrestrial POC and their temporal and spatial variations, and explore the controlling factors in degradation and preservation of POC during the transport process in the deep SCS. This project will promote the knowledge on the role of terrestrial POC in the carbon cycle of deep sea, especially in the marginal deep sea, and will be scientifically important to the understanding of ocean carbon cycle.