Seafloor flux estimates: oxygen, deep ocean carbon, carbonate, opal, nutrient particle fluxes, benthic fluxes and sediment accumulation, 2001 (U.S. JGOFS Synthesis & Modeling Phase project results)

<p>Research topic: Global synthesis of deep ocean carbon, carbonate, opal, and nutrient particle fluxes, benthic fluxes and sediment accumulation</p> <p>We request support to synthesize sea floor flux and sediment composition measurements into a global description of biogenic fluxes in the deep ocean and sediments to provide the basis for testing models of organic matter fluxes. This work will be comprised of three specific activities.</p> <ol> <li>Improve the fundamental data sets and compilations from which the estimated flux distributions and patterns are derived. This will include the incorporation of recent results (sedimentary organic C, CaCO₃, opal, accumulation rates, and benthic fluxes of O₂, TIC, nutrients, and selected tracers such as Ba and Ge) into the basic data sets; re-examination of the methods use to establish the mean sedimentary property fields; and expansion of the regions considered to include high latitude areas.</li> <br /> <li>Assimilate the individual measurements into a general Organic C - CaCO₃ - Opal diagenetic model to provide a mechanistically more meaningful method for establishing basin-wide flux patterns.&nbsp;&nbsp;</li> <br /> <li>Utilize the resulting flux distributions to test current models of particulate carbon fluxes in the ocean. For example, the importance of diatoms in determining POC fluxes can be assessed by comparing the ratio of silicate and organic carbon fluxes in the context of surface water productivity.</li> </ol> <p>&nbsp;</p> <p><br /> The development of an accurate understanding of global biogenic fluxes will require the synthesis of satellite, process, time-series and sea floor studies, each providing unique information. Sea floor studies, while not constraining temporal variability at the same time-scale as surface water processes, provide an assessment of the spatial distribution of deep fluxes not attainable by process and time-series studies and not visible by satellites. Sea floor studies further provide the link between ocean processes and the sediment record upon which paleoceanographic reconstructions depend. By providing improved quantitative descriptions of deep water column fluxes, benthic fluxes and sediment accumulation rates, this project will contribute to the following SMP objectives:</p> <ul> <li>Synthesis of observations of particulate export production</li> <li>The mechanisms and rates of mid- to deep-water particle flux and remineralizatio n as well as sediment diagenesis</li> <li>Controls on the distributions of the production, transport, and remineralization of calcium carbonate and silica</li> <li>Spatial extrapolation of estimates of biogeochemical fluxes (e.g. export production) from local to basin and global scales</li> </ul> <p>&nbsp;</p>研究主题：深海碳、碳酸盐、蛋白石及营养盐颗粒通量、底栖通量与沉积物堆积的全球综合研究 本研究申请经费支持，旨在将海底通量与沉积物组分实测数据整合为深海及沉积物中生源通量的全球描述，为有机质通量模型的验证提供依据。本项目包含三项具体任务： 1. 优化用于推导通量分布与格局的基础数据集与汇编数据集。具体工作包括：将最新研究成果（沉积物有机碳、碳酸钙（CaCO₃）、蛋白石、堆积速率，以及氧气（O₂）、总无机碳（Total Inorganic Carbon, TIC）、营养盐、钡（Ba）与锗（Ge）等选定示踪剂的底栖通量）纳入基础数据集；重新审视用于构建沉积物平均属性场的方法；并将研究区域扩展至高纬度海域。 2. 将各单次实测数据同化至通用的有机碳-碳酸钙（CaCO₃）-蛋白石成岩模型中，以建立一套机制上更具解释性的方法来构建全盆地尺度的通量格局。 3. 利用得到的通量分布验证当前海洋颗粒碳通量模型。例如，可通过结合表层水生产力背景，对比硅酸盐与有机碳通量的比值，评估硅藻在决定颗粒有机碳（Particulate Organic Carbon, POC）通量中的重要性。 要精准理解全球生源通量，需整合卫星遥感、过程研究、时间序列观测与海底研究的各类数据，这些研究手段各自提供独特的观测信息。海底研究虽无法像表层水过程研究那样约束相同时间尺度的时间变异性，却能评估过程研究与时间序列观测无法获取、卫星遥感无法观测的深海通量空间分布。此外，海底研究还可建立海洋过程与古海洋学重建所依赖的沉积物记录之间的关联。本项目通过优化对水柱深部通量、底栖通量及沉积物堆积速率的定量描述，将为以下SMP目标做出贡献： - 颗粒输出生产力观测数据的综合整合 - 中深层水体颗粒通量与再矿化作用及沉积物成岩作用的机制与速率 - 碳酸钙与二氧化硅的产生、输运及再矿化分布的调控因素 - 生物地球化学通量（如输出生产力）估算值从局地到盆地乃至全球尺度的空间外推