Variability in particle size distributions, sinking velocities, and fluxes in the northern Gulf of Alaska

颗粒从海洋的阳光照射区下沉到海洋内部，构成了将碳隔离到深海的主要组成部分，也被称为海洋的生物碳泵。从阳光照射区输出的颗粒物质的数量，以及这些通量相对于深度的逐渐减少，对整个海洋中碳和其他重要元素的分布产生了重大影响，并控制着大气中二氧化碳的浓度。由于这些原因，至关重要的是，我们要全面了解这些元素通量的大小，它们在空间和时间上的可变性，以及控制它们的过程。该项目的重点是在海洋生物碳泵的功能以及在高空间和时间分辨率下量化和监测其强度和效率的能力方面取得新的、广泛的信息发现。此外，该项目将通过与正在进行的苏厄德线长期观测计划合作，首次对阿拉斯加湾北部下沉的颗粒通量进行定量和机制研究。该项目将在一名早期职业教师的指导下进行，并为博士后研究员提供培训机会。研究结果将通过各种印刷和数字平台与更广泛的公众分享。从光带出来的碳通量和通过地下水的碳通量很少被量化和理解，特别是相对于其他主要的海洋碳流，如二氧化碳的海气交换或地表水的初级生产速率。无法区分颗粒浓度的可变性和下沉速度作为通量可变性的驱动因素是我们对生物碳泵的理解中的一个关键空白。由于化学、物理、生物和人为过程的动态相互作用，阿拉斯加湾等大陆架上方水域的碳和其他元素的循环非常复杂，因此阿拉斯加湾是研究这些过程的最佳地点。利用短期沉积物捕集器的创造性应用，结合使用一对独特的原位光学仪器，研究人员将致力于实现两个具体目标：1)量化小颗粒的平均下沉速度及其对各种大小颗粒的总碳通量的贡献；2)确定颗粒丰度和下沉速度的相对可变性，并评估其如何转化为阿拉斯加湾北部颗粒通量的可变模式。

The sinking of particles from the sunlit zone of the ocean into the ocean interior constitutes a dominant component of the sequestering of carbon into the deep ocean, otherwise known as the ocean's biological carbon pump. The quantities of particulate matter being exported out of the sunlit zone, as well as the tapering-off of these fluxes with respect to depth, have a substantial impact on the distribution of carbon and other important elements throughout the oceans and control the concentration of carbon dioxide in the atmosphere. For these reasons, it is critical that we gain a comprehensive understanding of the magnitude of these elemental fluxes, their variability in space and time, and the processes that control them. The focus of the of this project is to make new, broadly informative discoveries with regard to the function of the ocean's biological carbon pump and the ability to quantify and monitor its strength and efficiency at high spatial and temporal resolutions. In addition, this project will provide the first quantitative and mechanistic study of sinking particle fluxes in the northern Gulf of Alaska by working in conjunction with the ongoing Seward Line Long-term Observational Program. The project will be carried out under the direction of an early career faculty member and provide a training opportunity for a postdoctoral researcher. Results from the study will be shared with the broader public through a variety of print and digital platforms.The fluxes of carbon out of the euphotic zone and through subsurface waters are poorly quantified and understood, especially relative to other dominant oceanic carbon flows such as the air-sea gas exchange of carbon dioxide or rates of primary production in surface waters. The inability to differentiate between variability in particle concentration and sinking velocities as the drivers of flux variability is a critical gap in our understanding of the biological carbon pump. The Gulf of Alaska is an optimal site for investigating these processes as the cycling of carbon and other elements in waters above continental shelves, such as the Gulf of Alaska, is highly complex due to the dynamic interplay of chemical, physical, biological, and anthropogenic processes. Using a creative application of short-term sediment trap deployments combined with the use of a unique pair of in situ optical instruments, the researchers will aim to accomplish two specific goals: 1) Quantify the average sinking velocities of small particles and their contribution to the total carbon flux from particles of all sizes; and 2) Determine the relative variability in particle abundances and sinking velocities and assess how it translates into variable patterns of particle flux in the northern Gulf of Alaska.