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

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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.