EAGER: Quantifying Reversible and Irreversible Aqueous Secondary Organic Aerosol (SOA) Formation in the Atmosphere

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The project will examine the seasonal composition of ambient aerosols at an urban site in Maryland to better understand the contribution of aqueous-phase reactions occurring in aerosols as a source secondary organic aerosol (SOA). SOA, in contrast to gas-to-particle conversion, constitutes a major fraction of fine (PM2.5um) particle mass in the atmosphere. However, an under-prediction of SOA concentrations by state-of-the-art models indicates that a mechanistic understanding of SOA formation pathways is lacking. The uptake and reaction of soluble organic gases in aqueous aerosols is argued to be an important source of SOA formation that traditional models have neglected. SOA constitutes a major fraction of fine (PM2.5um) particle mass in the atmosphere, and impacts atmospheric visibility, radiation balance, and also human health. This investigation meets the EAGER criteria because a key part of the analytical work (i.e. fast switching of a tandem PILS ? particle into liquid sampler) the proposal depends upon is exploratory in nature, and the approach largely untested. If successful, this would also provide the foundation for a broader, more comprehensive definition of the composition and the reactivity of water soluble SOA transformation.