Sources of New Production and the Degredation of Organic Matter in a Tropical Margin Influenced by Seasonal Upwelling

新产量是指由硝酸盐吸收和N2固定所驱动的浮游植物总产量的组成部分。在海洋浮游生物生长的氮限制模型中，新产量可用于确定有机物质从表层向深层输出的上限。 因此，新的生产是确定海洋在二氧化碳等生物活性物质垂直流动中的作用的一个重要起点。 第二个关键因素是出口到深水区的新产量。 出口量和新产量都可能独立变化，需要了解这两者，以预测如何有效地从地表沃茨中去除物质。 以前的时间序列测量在委内瑞拉东北部的Cariaco盆地记录了惊人的生产力与冬季上升流期间和较低（虽然仍然温和）的生产在夏季以及可能的贡献，在深度的化学合成总有机出口。 因此，该区域是低纬度富营养海洋边缘区域的一个有用例子，其中大部分生产达到深水。 在这个项目中，来自哥伦比亚大学拉蒙特-道格拉斯地球观测站的研究人员将研究硝酸盐吸收和N2固定对总颗粒物出口的相对贡献，以及这些来源在Cariaco盆地的季节性变化。 拟议的工作是正在进行的CARIACO时间序列项目的一项配套工作。后一项核心工作将提供基本的后勤、物理和化学以及生产力计量，本项目的工作将侧重于新生产的来源、数量和出口效率。 直接培养法将用于测量硝酸盐吸收和N2固定在表面沃茨的季节性变化，使用15 N示踪技术的硝酸盐和二氮气体以及乙炔还原N2固定。 两年以上的季节性采样率将提供一个基础，估计相对重要性的N2固定，一个潜在的重要输入组合氮的海洋。除了沉积物收集器比较外，还将采用最近开发的13 C稀释法来测量输出的总体效率，以估计地下碳呼吸。 最后，将利用这些速率测量值，根据遥感信息校准该区域新的生产和出口模式。该模型将明确估计N2固定。这项工作将有助于限制热带边缘在向海洋供应化合氮以及在海洋总碳吸收方面的累积作用。

ABSTRACTOCE-0118867New production is that component of total phytoplankton production fueled by nitrate uptake and the fixation of N2. In a nitrogen-limited model of ocean plankton growth, new production can be used to define an upper limit for the export of organic material from the surface to deeper layers. Thus, new production is an important starting point to determine the ocean's role in the vertical flux of bio-active materials such as carbon dioxide. A second critical factor is the amount of new production that is exported to depth. Both export and new production can vary independently and both need to be understood to predict how efficiently material will be removed from surface waters. Previous time series measurements in the Cariaco Basin off northeast Venezuela recorded prodigious productivity associated with the winter upwelling period and lower (although still moderate) production in summer as well as the possible contribution of chemosynthesis at depth to the total organic export. Thus, the region is a useful example of a low-latitude eutrophic-ocean margin region in which much of the production reaches deep water. In this project, researchers from the Lamont-Dougherty Earth Observatory of Columbia University will study the relative contribution of nitrate uptake and N2 fixation to total particulate export and how these sources vary seasonally in the Cariaco Basin. The proposed work is a companion effort with the ongoing CARIACO Time-Series Project. While the latter core effort will provide the basic logistics, physical and chemical and productivity measurements, the work undertaken in this project will focus on the source, amount and export efficiency of new production. Direct incubation methods will be used to measure the seasonal changes in nitrate uptake and N2 fixation in surface waters using both 15 N tracer techniques for nitrate and di-nitrogen gas as well as the acetylene reduction for N2 fixation. Seasonal sampling of these rates over two years will provide a basis for estimating the relative importance of N2 fixation, a potentially important input of combined nitrogen to the ocean. In addition to sediment trap comparisons, the overall efficiency of export also will be measured with a recently developed 13C dilution method for estimating sub-surface carbon respiration. Finally, these rate measurements will be used to calibrate a model of new production and export in the region based on remotely sensed information. The model will explicitly estimate N2 fixation. This work will help to constrain the cumulative role of tropical margins in the supply of combined nitrogen to the ocean as well as in total-ocean carbon uptake.