Benthic Mineralization of Organic Matter on the Continental Rise and the Dissolution of CaCo3 at the Deep Seafloor

在之前的拨款期间，开发了在船上孔隙水取样和孵卵期间进行原位底栖生物通量室测量和在原位温度和压力下检索和维持沉积物岩心所需的仪器。本项目将利用这些仪器研究海洋碳循环的两个重要方面，即有机质的矿化和深海表层沉积物中CaCO3溶解动力学。具体来说，将研究西非高产边缘附近的地点（与法国赞助的eumeeli项目合作）以及赤道西太平洋溶斜层上下的地点。在每个位置，将确定有机质、蛋白石和CaCO3的颗粒输入，这些相在地表沉积物中的矿化和溶解速率以及埋藏速率。当这些信息通过模型与环境参数（如底水CaCO3饱和状态、扩散边界层厚度等）耦合时，将允许解决以下问题：非洲海底的有机物通量对大西洋深处的碳收支重要吗？2. 从非洲流出的有机物质是否可以由沉积物捕集器测量的垂直降雨率来支持？3. 西非深海的反硝化作用重要吗？4. CaCO3在海底的溶解速率常数是多少？5. 沉积CaCO3的溶解在多大程度上中和了代谢CO2 ？6. 通过扩散亚层的运输是否限制了深海中CaCO3的总溶解速率？

During the preceeding grant periods, the instrumentation required to perform in situ benthic flux chamber measurements and to retrieve and maintain sediment cores at in situ temperatures and pressures during shipboard pore water sampling and incubations were developed. This project will utilize these instruments to study two important aspects of the marine carbon cycle, the mineralization of organic matter and the kinetics of CaCO3 dissolution in deep sea surface sediments. Specifically, sites adjacent to the highly productive west African margin (in collaboration with the French-sponsored EUMELI program) and sites above and below the lysocline in the western equatorial Pacific will be studied. At each location, the particulate input of organic matter, opal, and CaCO3, the mineralization and dissolution rate of these phases in surface sediments, and the burial rate will be determined. This information, when coupled through models to environmental parameters such as bottom water CaCO3 saturation state, diffusive boundary layer thickness, etc., will permit the following questions to be addressed: 1. Are organic matter fluxes to the seafloor off Africa important to deep Atlantic carbon budgets? 2. Can organic matter fluxes off Africa be supported by vertical rain rates as measured by sediment traps? 3. Is denitrification at the deep seafloor important off west Africa? 4. What is the CaCO3 dissolution rate constant at the seafloor? 5. To what extent is metabolic CO2 neutralized by the dissolution of sedimentary CaCO3? 6. Does transport across the diffusive sublayer limit the total CaCO3 dissolution rate in the deep sea?