Collaborative Research: Management and Implementation of US GEOTRACES GP17 Section: South Pacific and Southern Ocean (GP17-OCE)

作为美国GEOTRACES项目的一部分，该项目将支持从塔希提岛到智利的一个研究考察项目的管理和实施，该项目将在对全球营养和碳循环具有重要意义的海洋区域对大量微量元素和同位素（TEI）进行采样。GEOTRACES是化学海洋学领域的一项全球性努力，其目标是了解海洋中微量元素及其同位素的分布。确定这些元素和同位素的分布将增进对形成其分布的过程的了解，例如洋流和物质通量，以及对依赖这些元素的过程的了解，例如浮游植物的生长和海洋生态系统的支持。拟议中的游轮将穿越南太平洋环流、南极环极流、铁有限的南极水域和智利边缘。与两个重叠的考察站（GP17-ANT）一起，研究小组将在海洋中最缺乏营养的水域和生产力最高的南极地区建立一个海洋区域，这一地区在调节全球碳循环方面发挥着巨大的作用。这次考察将支持和提供管理基础设施，为其他参与的科学项目提供支持，这些项目的重点是测量沿着这一段的特定外部通量和tei的内部循环。南太平洋环流和南大洋太平洋部分在全球水团环流和相关的全球热量、碳和营养物质转移中发挥着关键作用，但由于其位置偏远，对它们的研究长期不足。这些区域具有强大的动力锋面，地下水团在此上升和俯冲，这些区域的生物和化学过程决定了输往低纬度水域的营养化学计量学和示踪剂浓度。太平洋部分是极低外部TEI地表通量的末端成员，因此是限制快速变化的南极大陆输入的重要区域。与其他海洋盆地相比，这些地区的TEI循环被认为是由生物吸收、再生和清除等内部循环过程主导的，而这些过程在全球海洋模式中很少得到体现。这次航行将使受资助的研究人员能够解决以下研究问题：1)该地区外部TEI通量的相对速率是多少，包括尘埃、沉积物、热液和冰冻圈通量？2)支持生产力的（微）养分制度是什么？生物量积累、出口和再生对出口物质的TEI循环和化学计量学有什么影响？3)俯冲水体的TEI和营养化学计量特征是什么？在向北移动的过程中，清除和再生如何影响这些特征？该管理项目有几个目标：1)计划和协调2021-2022年55天的研究巡航；2)使用传统和痕量金属“清洁”采样系统获取TEI样品，并促进对大气气溶胶和大体积颗粒和放射性核素的采样；3)获取水文数据和盐度、溶解氧、藻类色素和常量营养素样本；并将这些数据传送到相关的存储库；4)确保遵循和报告适当的QA/QC协议，以及GEOTRACES互校准协议；5)准备最终的巡航报告，并随数据发布；6)协调所有资助的巡航调查员，以及拟议的GP17-ANT巡航的领导；7)开展更广泛的影响工作，利用沉浸式技术吸引公众参与海洋学研究。这项工作的动机和海上挑战将通过与德克萨斯a&m大学可视化实时实验室合作，通过创造沉浸式360/虚拟现实体验，向公众传达。通过虚拟现实，用户将亲身体验海上生活和TEI数据收集所带来的体验。虚拟现实/数字游戏和360°体验将通过GEOTRACES外展网站、PI与当地学校、图书馆、STEM夏令营和成人服务组织的合作以及与美国国家科学院的合作进行分发。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。

This award will support the management and implementation of a research expedition from Tahiti to Chile that will enable sampling for a broad suite of trace elements and isotopes (TEI) across oceanographic regions of importance to global nutrient and carbon cycling as part of the U.S. GEOTRACES program. GEOTRACES is a global effort in the field of Chemical Oceanography, the goal of which is to understand the distributions of trace elements and their isotopes in the ocean. Determining the distributions of these elements and isotopes will increase understanding of processes that shape their distributions, such as ocean currents and material fluxes, and also the processes that depend on these elements, such as the growth of phytoplankton and the support of ocean ecosystems. The proposed cruise will cross the South Pacific Gyre, the Antarctic Circumpolar Current, iron-limited Antarctic waters, and the Chilean margin. In combination with a proposed companion GEOTRACES expedition on a research icebreaker (GP17-ANT) that will be joined by two overlapping stations, the team of investigators will create an ocean section from the ocean’s most nutrient-poor waters to its highly-productive Antarctic polar region – a region that plays an outsized role in modulating the global carbon cycle. The expedition will support and provide management infrastructure for additional participating science projects focused on measuring specific external fluxes and internal cycling of TEIs along this section. The South Pacific Gyre and Pacific sector of the Southern Ocean play critical roles in global water mass circulation and associated global transfer of heat, carbon, and nutrients, but they are chronically understudied for TEIs due to their remote locale. These are regions of strong, dynamic fronts where sub-surface water masses upwell and subduct, and biological and chemical processes in these zones determine nutrient stoichiometries and tracer concentrations in waters exported to lower latitudes. The Pacific sector represents an end member of extremely low external TEI surface fluxes and thus an important region to constrain inputs from the rapidly-changing Antarctic continent. Compared to other ocean basins, TEI cycling in these regions is thought to be dominated by internal cycling processes such as biological uptake, regeneration, and scavenging, and these are poorly represented in global ocean models. The cruise will enable funded investigators to address research questions such as: 1) what are relative rates of external TEI fluxes to this region, including dust, sediment, hydrothermal, and cryospheric fluxes? 2) What are the (micro) nutrient regimes that support productivity, and what impacts do biomass accumulation, export, and regeneration have on TEI cycling and stoichiometries of exported material? 3) What are TEI and nutrient stoichiometries of subducting water masses, and how do scavenging and regeneration impact these during transport northward? This management project has several objectives: 1) plan and coordinate a 55-day research cruise in 2021-2022; 2) use both conventional and trace-metal ‘clean’ sampling systems to obtain TEI samples, as well as facilitate sampling for atmospheric aerosols and large volume particles and radionuclides; 3) acquire hydrographic data and samples for salinity, dissolved oxygen, algal pigments, and macro-nutrients; and deliver these data to relevant repositories; 4) ensure that proper QA/QC protocols, as well as GEOTRACES intercalibration protocols, are followed and reported; 5) prepare the final cruise report to be posted with data; 6) coordinate between all funded cruise investigators, as well as with leaders of proposed GP17-ANT cruise; and 7) conduct broader impact efforts that will engage the public in oceanographic research using immersive technology. The motivations for, and at-sea challenges of this work will be communicated to the general public through creation of immersive 360/Virtual Reality experiences, via a collaboration with the Texas A&M University Visualization LIVE Lab. Through Virtual Reality, users will experience firsthand what life and TEI data collection at sea entail. Virtual reality/digital games and 360° experiences will be distributed through GEOTRACES outreach websites, through PI engagement with local schools, libraries, STEM summer camps, and adult service organizations, and through a collaboration with the National Academy of Sciences.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.