ERI: Direct Photochemistry Effects on Carbonyl/Ammonium-derived Aqueous Secondary Organic Aerosol

Lafayette College, Easton PA

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Aerosols have a significant impact on air quality, human health, and Earth’s climate via interactions with sunlight and in forming clouds. Most atmospheric aerosols are secondary organic aerosols(SOA), formed via the oxidation of volatile organic compounds followed by partitioning in the aerosol condensed phase particulate matter. Carbonyl-containing volatile organic compounds (CVOCs) are significant contributors to SOA. However, the impact of photochemistry of CVOCs on the size, composition and physical properties of SOA is not well understood. The overarching goal of this ERI project is to address this knowledge gap. To achieve this goal, the Principal Investigator (PI) and his team will measure the surface tension, light absorbance, and compositions of COVC-derived aqueous SOA solutions under varying amounts of sunlight. The successful completion of this project will benefit society through the development of new fundamental knowledge on the impact of aerosols on air quality, cloud formation, and climate change. Further benefits to society will be achieved through student education and training including the mentoring of two undergraduate students at Lafayette College. Carbonyl-containing volatile organic compounds (CVOCs) such as glyoxal and methylglyoxal and their reactive products are significant contributors to the formation of aqueous solutions of secondary organic aerosol (SOA). The overarching goal of this ERI project is to advance the fundamental understanding of the bulk and surface aqueous photochemistry of CVOCs and its impacts on the size, composition, and physical properties of aqueous solutions of SOA. To advance this goal, the PI and his team propose to carry out an integrated experimental program structured around three tasks. Task 1 will modify the Lafayette continuous-flow atmospheric chamber though the addition of UV lamp arrays to enable the exposure of aqueous SOA solutions to varying amounts of radiation under controlled relative humidity conditions. Task 2 will measure changes in the size distribution, composition, and surface tension of SOA solutions using aerosolized aqueous mixtures of CVOCs as model systems. Task 3 will analyze the collected data and compare the changes in the physical/chemical properties measured in Task 2 to those from analogous bulk solution and droplet samples. The successful completion of this research has the potential to advance our fundamental understanding of the formation and physical/chemical properties of aqueous SoA solutions and their impact on air quality, cloud formation, radiative forcing, and climate change. 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.