Collaborative Research: Biogeochemical Modeling of Carbon Partitioning in the Pacific: the Role of Si and Fe in Regulating Production by Siliceous and Calcifying Phytoplankton

物理和生物的相互作用在大气、上层海洋、深海和沉积物之间的碳分配中起着复杂的作用。目前，跨学科的模型提供了最好的方法来检验关于碳分配如何在数年到数世纪的时间尺度上在不同的海洋区域受到调节的假设。一个新的跨学科模型将整合几个领域的进展，以检验两个相关的假设：1)硅藻和其他浮游植物群(如非？硅质浮游生物和钙化浮游植物)显著影响碳分配，且具有时空差异，受Si和Fe组合的调控；2)南大洋中Si捕获的变化影响了为赤道上升流提供养分的“模式”水中Si(OH)4的浓度，而赤道浮游植物对Si和C的吸收改变了空气？赤道的海洋二氧化碳交换。一个由生物和化学海洋学家和建模者组成的跨学科科学团队将通过四种方法解决这些问题。首先，将钙化浮游植物成分添加到现有模型中，并用于纳入水柱生产和溶解CaC03。其次，将设计和执行模型实验，以探索硅（硅藻）和非硅（硅藻）之间切换的调节。硅质（微质和钙化）浮游生物。第三，将赤道太平洋的改进块地球化学模型在空间上扩展到包括南大洋，并用于高纬度“模态”水域与赤道上升流源水域之间的一系列过程的模拟实验。最后,铁?该模型浮游植物组分的敏感生长参数将被操纵，以测试赤道太平洋和南大洋生态系统对铁富集的响应。这些目标代表了开发耦合物理生物地球化学模型以探索海洋生物地球化学过程对气候变化的响应的重要一步。

Physical and biological interactions play a complex role in the partitioning of carbon between the atmosphere, upper ocean, deep ocean and sediments. At present, interdisciplinary models offer the best means to test hypotheses about how carbon partitioning is regulated in various oceanic regions on time scales of years to centuries. A new interdisciplinary model will integrate advances in several areas to test two related hypotheses: 1) that switches in community and productivity dominance between diatoms and other phytoplankton groups (e.g. non?siliceous picoplankton and calcifying phytoplankton) significantly affect carbon partitioning, vary spatially and temporally and are regulated by a combination of Si and Fe in combination; 2) that changes in Si trapping in the Southern Ocean affect Si(OH)4 concentrations in the "mode" waters that feed equatorial upwelling, and that Si and C uptake by equatorial phytoplankton alters air?sea exchange of carbon dioxide at the equator.An interdisciplinary science team of biological and chemical oceanographers and modelers will address these issues via four approaches. First, a calcifying phytoplankton component will be added to an existing model and used to incorporate water column production and dissolution of CaC03. Second, model experiments will be designed and executed to explore the regulation of switching between siliceous (diatoms) and non?siliceous (pico and calcifying) plankton. Third, an improved blogeochemical model developed for the equatorial Pacific will be spatially expanded to include the Southern Ocean, and used to conduct a series of simulation experiments on the processes that link high latitude "mode" water regions with the source waters for equatorial upwelling. Finally, iron?sensitive growth parameters of the phytoplankton components of the model will be manipulated to test the ecosystem response to iron enrichment in both the equatorial Pacific Ocean and the Southern Ocean. These objectives represent a significant step in the development of coupled physical biogeochemical models for exploring the response of marine biogeochemical processes to climate change.