Aqueous Secondary Organic Aerosol Formation from Acetylene Oxidation in Simulated Clouds

The atmosphere contains a variety of types of aerosols that collectively impact the climate, earth’s radiation budget, and human health. Secondary organic aerosols make up a significant portion of this burden, but are not well understood. Formation of secondary organic aerosols (SOA) begins with the direct emission of precursor gases from both natural and anthropogenic sources. Once in the atmosphere, photolysis and oxidation processes convert volatile organic species into products that form new particles or add to existing ones. This has been understood to occur efficiently in the gas phase, but recent studies have also found that SOA forms through aqueous phase reactions. The use of the Multiphase Aging and Production of Particles (MAPP) chamber focuses on the realistic formation of clouds to study the production of aqueous secondary organic aerosols (aqSOA). Acetylene is injected into the chamber and oxidized by hydroxyl radicals to create glyoxal, which readily partitions from the gas to aqueous phase because of its high Henry’s Law constant. This study quantified the formation of secondary organic aerosols within cloud droplets that form after the gas phase oxidation of acetylene.