US GEOTRACES GP17-OCE and GP17-ANT: Mapping zinc speciation in the Southern Ocean overturning circulation to test the zinc scavenging hypothesis

美国 GEOTRACES GP17-OCE 和 GP17-ANT：绘制南大洋翻转环流中的锌形态图，以检验锌清除假说

• 批准号: 2049151
• 负责人: Nicholas Hawco
• 金额: $ 28.97万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2049151&HistoricalAwards=false
• 关键词: US; GEOTRACES; GP17; OCE; ANT

The Southern Ocean plays a significant role in the global carbon cycle because deep ocean waters rich in CO2 are brought into the surface layer and can exchange with the atmosphere. The growth of phytoplankton counteracts this carbon source by fixing CO2 into biomass, which can sink back to the deep sea. While the Southern Ocean is rich in macronutrients that support phytoplankton growth, key micronutrients such as iron, manganese and zinc are at very low abundance. Of these metals, only iron has been found to limit phytoplankton productivity on a large scale, but few observations of Zn and Mn have been made. This proposal seeks to map bioavailable Zn concentrations across an oceanographic transect from the South Pacific Ocean to the Amundsen Sea. At low abundance, Zn scarcity can limit phytoplankton, but Zn can also affect the uptake of other scarce metals, especially Mn. Measurements made as part of this project will determine the extent of limiting and toxic levels of Zn in this critical but undersampled region of the oceans. Such constraints are necessary for modelling changes to the oceanic Zn cycle – and its effect on phytoplankton activity – under past and future climate scenarios. As part of the GEOTRACES GP17 OCE and ANT expeditions, parameters governing the reactivity of Zn will be measured in high vertical and latitudinal resolution across a transect extending several thousand kilometers and crossing formation regions of globally important water masses. Voltammetry techniques will be used to determine the concentrations of free zinc (Zn’) and Zn-binding organic ligands dissolved in seawater for hundreds of samples. Together with other investigators in the GEOTRACES program, these measurements will constrain the reactivity of Zn’ in the deep ocean and define empirical relationships between Zn’ and phytoplankton metal uptake. This is essential for understanding the global distribution of Zn and other micronutrients in the oceans and their potential to affect primary production.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.

南大洋在全球碳循环中发挥着重要作用，因为富含二氧化碳的深海海水被带到表层并可以与大气交换。浮游植物的生长通过将二氧化碳固定在生物质中来抵消这种碳源，而生物质可以沉回深海。虽然南大洋富含支持浮游植物生长的常量营养素，但铁、锰和锌等关键微量营养素的丰度非常低。在这些金属中，只有铁被发现能大规模限制浮游植物的生产力，但对锌和锰的观察却很少。该提案旨在绘制从南太平洋到阿蒙森海的海洋横断面的生物可​​利用锌浓度图。在低丰度下，锌的稀缺会限制浮游植物，但锌也会影响其他稀有金属的吸收，尤其是锰。作为该项目的一部分进行的测量将确定这一关键但采样不足的海洋区域中锌的限制程度和有毒水平。这些约束对于在过去和未来的气候情景下模拟海洋锌循环的变化及其对浮游植物活动的影响是必要的。 作为 GEOTRACES GP17 OCE 和 ANT 探险的一部分，将以高垂直和纬度分辨率测量控制锌反应性的参数，跨越绵延数千公里并穿越全球重要水团形成区域的横断面。伏安法技术将用于测定数百个样品中溶解在海水中的游离锌 (Zn’) 和锌结合有机配体的浓度。与 GEOTRACES 计划的其他研究人员一起，这些测量结果将限制深海中 Zn' 的反应性，并定义 Zn' 和浮游植物金属吸收之间的经验关系。这对于了解海洋中锌和其他微量营养素的全球分布及其影响初级生产的潜力至关重要。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。