Trace element cycling in upwelling filaments in the California Current System

锰、铁、镍、钴、铜和锌等微量元素在海洋生物过程中发挥着重要作用。在浮游植物生长并支撑海洋食物网基础的地表水中，微量元素通常以极低的浓度存在。这对海洋生物提出了巨大的挑战，微量元素可能是浮游植物生产力的限制因素。海洋系统中的生物过程，如浮游植物的生长、放牧、溶解有机物的产生和沉积，反过来又对微量元素在海洋中的循环产生重要影响。这些相互关系是复杂的，并不是很好理解，但它们对生态系统生产力和全球营养循环具有重要影响。本研究旨在研究加利福尼亚海流系统中一个动态的、具有重要生态意义的环境——上升流细丝中微量元素分布与化学和生物过程的关系。实地研究将利用正在进行的加州当前生态系统长期生态研究（cce - lt）网站，该网站已经资助了2019年和2021年的游轮计划。该项目将支持研究生的教育和培训，并通过CCE-LTER项目参与PI和研究生的教育和外展活动，包括指导本科生的研究项目，并通过斯克里普斯的桦树水族馆为公共教育和外展做出贡献。微量元素的有效性越来越被认为是影响海洋浮游植物群落生产力和结构的重要因素。微量元素本身在海洋系统中的停留时间、化学形态和循环等方面受到生物过程的强烈影响。通过现场同时测定多种微量元素，充分表征上层海洋系统生物和物理动力学的现场过程研究有可能极大地帮助我们了解微量元素与生物群之间的耦合相互作用，但由于其跨学科的复杂性和费用，此类研究相对较少。该提案旨在通过利用正在进行的加州当前生态系统长期生态研究计划（cce - lt）来支持进行这样的研究。即将在2019年和2021年进行的两次资助LTER过程巡航将通过测绘、详细采样和拉格朗日过程测量相结合，描述上升流细丝在离岸移动时的生物地球化学和生态演化。该项目资助购买和设置一个seaFAST pico浓缩系统和ICP-MS分析时间，这将使这些巡航的背景下研究多种微量元素成为可能。这种类型的中尺度特征很少从微量元素生物地球化学的角度进行表征，我们预计我们的发现将引起海洋学界的广泛兴趣。关于上升流细丝中微量元素的来源、汇和循环的一些假设将在拟议的工作中进行检验。该项目还将利用CCE-LTER内部正在进行的研究合作，将多元素微量元素数据集与群落结构和功能以及溶解有机质组成的分子水平信息相结合。这将有助于探索生物群落对多因子共限的响应，有机分子在介导痕量金属循环中的作用，以及痕量金属循环与碳、氮、硅循环的耦合。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Trace element micronutrients such as manganese, iron, nickel, cobalt, copper and zinc play important roles in biological processes in the ocean. In surface waters where phytoplankton grow and support the base of the marine food web, trace elements are often present at vanishingly small concentrations. This presents great challenges to marine life, and trace elements can be limiting factors for phytoplankton productivity. Biological processes in marine systems like phytoplankton growth, grazing, dissolved organic matter production, and sedimentation can in turn have important impacts on how trace elements cycle through the ocean. These inter-relationships are complex and not very well understood, but they have important ramifications for ecosystem productivity and global nutrient cycling. The research proposed here seeks to study the relationships between trace element distributions and chemistry and biological processes in a dynamic and ecologically significant environment - upwelling filaments in the coastal California Current System. Field studies will take advantage of the ongoing California Current Ecosystem Long Term Ecological Research (CCE-LTER) site, which already has funded cruises planned for 2019 and 2021. This project will support the education and training of graduate students, and the participation of both the PI and graduate students in education and outreach activities carried out through the CCE-LTER project, including mentoring undergraduates in research projects and contributing to public education and outreach through the Birch Aquarium at Scripps.The availability of trace element micronutrients is increasingly recognized as an important influence on the productivity and structure of marine phytoplankton communities. Trace elements themselves are strongly influenced by biological processes in terms of their residence time, chemical speciation, and cycling in marine systems. Field process studies which fully characterize the biological and physical dynamics of upper ocean systems with simultaneous determination of multiple trace elements in situ have the potential to greatly inform our understanding of the coupled interactions between trace elements and biota, but such studies are comparatively rare due to their interdisciplinary complexity and expense. This proposal seeks support to perform such a study by leveraging the ongoing California Current Ecosystem Long Term Ecological Research program (CCE-LTER). Two upcoming funded LTER process cruises in 2019 and 2021 will characterize the biogeochemical and ecological evolution of upwelling filaments as they move offshore via a combination of survey mapping, detailed sampling and Lagrangian process measurements. This project funds the acquisition and setup of a seaFAST pico preconcentration system and ICP-MS analytical time which will enable the study of multiple trace elements in the context of these cruises. This type of mesoscale feature has rarely been characterized from the standpoint of trace element biogeochemistry, and we anticipate that our findings will be of broad interest to the oceanographic community. A number of hypotheses regarding the sources, sinks and cycling of trace elements in an upwelling filament will be examined in the proposed work. This project will also take advantage of ongoing research collaborations within CCE-LTER to couple multi-elemental trace element data sets with molecular-level information on community structure and function and dissolved organic matter composition. This will facilitate exploration of the response of biological communities to multi-factorial co-limitation, the role of organic molecules in mediating trace metal cycles, and the coupling of trace metal cycles with the cycles of carbon, nitrogen, and silica.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.