CAREER: Characterizing African Dust Aging and Seasonal Contributions of Dust and Biomass Burning to Aerosol Biogeochemical Cycles

这个项目的重点是研究北大西洋盆地非洲沙尘的来源和老化。该研究的中心假设是，化学老化的非洲沙尘颗粒是夏季向北大西洋盆地提供可溶性磷(P)和铁（Fe）的主要来源，而燃烧和生物质燃烧气溶胶是冬季和春季的主要来源，它们比夏季老化的沙尘贡献了更多的可溶性磷和铁。可溶形式的营养物质，如磷和铁，可以对世界海洋中的生物地球化学循环产生重大影响，并可能影响大气中二氧化碳的封存，从而影响气候。这项工作的研究目标是：1)表征非洲沙尘在运输过程中老化的化学机制，并确定其对P和Fe溶解度的影响；2)通过季节测量确定北大西洋盆地生物质燃烧和燃烧对P和Fe可溶性形态的贡献。这项研究将使用来自两个地点的数据，这些数据几十年来一直用于记录非洲沙尘的远程传输：1)位于佛罗里达州迈阿密弗吉尼亚岛的罗森斯蒂尔海洋与大气科学学院（RSMAS），以及2)迈阿密大学巴巴多斯大气化学观测站（BACO）。将评估粉尘样品中的几个参数，以更好地了解增加P和Fe溶解度的机制。这些是：(1)是否发生了老化，(2)粉尘颗粒的酸度，(3)哪些特定的酸与粉尘内部混合；4)燃烧气溶胶中是否存在可溶性磷和铁。这项工作对加勒比地区关注非洲沙尘对健康影响的社区非常有意义。这些教育活动将促进分析技术的早期实践职业培训，并为来自资源不足社区的博士生、本科生和高中生发展科学写作和沟通技巧。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 project is focused on the study of the sources and aging of African dust in the North Atlantic Basin. The central hypothesis of the research is that chemically-aged African dust particles are the primary source of soluble phosphorus (P) and iron (Fe) to the North Atlantic Basin in the summertime, whereas combustion and biomass burning aerosol are the primary sources in the winter and spring, contributing even larger quantities of soluble P and Fe than summertime aged dust. Soluble forms of nutrients, such as P and Fe, can have a large influence on biogeochemical cycles in the world’s oceans and can impact the sequestration of atmospheric carbon dioxide (CO2), affecting climate.The research objectives of the effort are to: 1) characterize the chemical mechanisms that age African dust during transport and determine their impact on the solubility of P and Fe, and 2) determine the contributions of biomass burning and combustion to soluble forms of P and Fe in the North Atlantic Basin through seasonal measurements. Data from two sites that have been used for decades to document the long-range transport of African dust will be used in this study: 1) the Rosenstiel School of Marine & Atmospheric Science (RSMAS) on Virginia Key in Miami, Florida, and 2) the University of Miami’s Barbados Atmospheric Chemistry Observatory (BACO). Several parameters will be evaluated in the dust samples to better understand the mechanisms that increase the solubility of P and Fe. These are: (1) whether aging has taken place, (2) the acidity of the dust particles, (3) which specific acids are internally mixed with dust; and 4) whether soluble P and Fe from combustion aerosols are also present. The work is of great interest to communities in the Caribbean that are concerned about the health impacts of transported African dust. The educational activities will both facilitate hands-on early career training in analytical techniques as well as develop science writing and communication skills for Ph.D. students, undergraduates, and high school students from under-resourced communities.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.