Collaborative Research: Quantifying the atmospheric flux of bio-active trace elements to the southwestern Indian Ocean

合作研究：量化西南印度洋生物活性微量元素的大气通量

• 批准号: 2023011
• 负责人: Mark Stephens
• 金额: $ 34.32万
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-11-01 至 2024-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023011&HistoricalAwards=false
• 关键词: Collaborative; Research; Quantifying; atmospheric; flux

Marine phytoplankton (microscopic photosynthetic algae) produce about half of the oxygen we breath and remove billions of tons of carbon dioxide from the atmosphere each year. This primary productivity plays a central role in controlling atmospheric carbon dioxide (pCO2) levels and the global climate. Yet, phytoplankton productivity is limited by lack of iron (an essential trace element) in about 40% of the global ocean. While phytoplankton productivity helps remove carbon dioxide from the atmosphere, it also removes iron and other essential trace elements (like manganese, cobalt, copper, and zinc) from the upper ocean. One critical issue is, “What are the sources for these essential trace elements that are needed to replace those removed by phytoplankton to keep the annual productivity cycles going?” This is especially important in the waters of the Southern Ocean around Antarctica, where ocean circulation brings deep water to the surface; water that is enriched in nutrients like nitrate and phosphate but depleted in essential trace elements. The main source for iron in the open ocean is from desert dust deposition. In this project, scientists will collect aerosols (fine particles in the air) and rain samples over the Southern Ocean to measure how much iron (and the other essential trace elements) is depositing to surface waters. Other scientists will be measuring how fast phytoplankton are growing, and together we will learn how the input of trace elements from dust helps to remove carbon dioxide from the atmosphere. This information can then be used to help predict the future of Earth’s climate. The scientists will communicate results of their study to the public via open house events at their respective campuses, as well as through online forums. One undergraduate student from Florida International University, a leading minority serving university, would be supported and trained as part of this project. The project will measure the aerosol fractional solubility and atmospheric deposition of bio-essential trace elements as part of a multidisciplinary project studying trace element sources, transformations and sinks in the Indian Ocean sector of the Southern Ocean. The research cruise track will cross the currents and oceanographic fronts that are major pathways of the general circulation in the region where we expect to find multiple possible aerosol sources, and where aerosol Fe deposition and rainfall rates are predicted to range over 1-2 orders of magnitude. Aerosol samples (bulk and size-fractionated) will be collected on a daily basis and event-based rain samples to be analyzed for total and soluble major and trace elements including nitrate, phosphate, silicate, chloride, sulfate, Na, Mg, Al, V, Mn, Fe, Co, Ni, Cu, Zn, and Cd. In addition, scientists will analyze the water-soluble organic compounds in aerosols, focusing on compounds such as oxalate and methane-sulfonic acid (MSA) that enhance aerosol trace element solubility. Scientists will use Be-7 concentrations in aerosols and the upper water column to calculate aerosol bulk deposition velocities and test whether the relationship between rainfall rate and bulk deposition velocity that we have previously published can be applied on a more global basis. Further, scientists will use the trace element concentration data along with air-mass back trajectory analysis to apportion the aerosols between anthropogenic and natural sources, and study how aerosol sources affect the fractional solubility. Aerosol and rain subsamples will be provided to collaborators on the cruise for the analysis of additional important parameters.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.

海洋浮游植物（微观光合藻类）每年呼吸大约一半的氧气，并消除数十亿个二氧化碳的大气层。痕量元素）大约40％，而植物量有助于从大气中去除二氧化碳，它也可以去除铁和其他痕量痕量痕量元素（钴，钴，铜和锌）。 “什么是什么来源”，将浮游植物替换为每年的生产力周期的OSE所需的痕量元素？元素。为了生长，我们将使用来自大气的二氧化物的痕量元素来预测地球气候的未来。以及通过在线论坛（通过在线论坛）。海洋样品（批量和尺寸分级）将每天收集和基于事件的降雨样本，以分析总体和微量元素，包括硝酸盐，硅酸盐，硅TE，NA，MG，MG，AL，AL，V，MN，MN，MN，FE，FE， CO，Ni，Cu，Zn和CD。在气溶胶和上水柱中，计算Aerosolk沉积物，并测试降雨速率散装速度的关系是否可以在更全球的基础上使用。子样本将是在分析其他重要参数的巡航方面的合作者。该奖项反映了NSF的指导任务，并被认为是值得通过Toundation的知识分子优点和更广泛的Impact Impacts审查标准来评估值得支持的。