Linking Gas, Particulate, and Toxic Endpoints to Air Emissions In The Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM)
HAVALA PYE, Bryan Place, Benjamin Murphy, Karl Seltzer, Chris Allen, Ivan Piletic, Emma D'Ambro, Rebecca Schwantes, Matthew Coggon, Sara Farrell, Emily Saunders, Lu Xu, Golam Sarwar, William Hutzell, Kristen Foley, George Pouliot, William R. Stockwell,
United States Environmental Protection Agency Abstract Number: 113
Working Group: Carbonaceous Aerosol
AbstractReactive organic carbon (ROC) is ubiquitous in the atmosphere. Chemical mechanisms describe the atmospheric transformations of ROC from interactions with nitrogen oxides and other inorganic species allowing for air emissions to be linked to atmospheric pollutants with implications for climate and health. In this work, we present the first version of the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) which provides transparent rules to map individual compounds to mechanism species and span the entire volatility range of atmospheric ROC. Radical chemistry was fully coupled to pathways leading to secondary organic aerosol (SOA), including autoxidation, providing additional constraints on ozone formation and allowing for consideration of SOA precursors such as phenolic and furan compounds not previously treated in chemical transport models. For novel ROC constituents, specifically semi- and intermediate volatility compounds, oxidation reactions were added that generate higher molecular weight products important for SOA formation and fragments contributing to the radical budget. In addition, explicit hazardous air pollutants were added resulting in 9 species covering 50% to 90% of the estimated cancer and non-cancer health risk due to inhalation. We use estimated emissions of ROC in 2017 from the EPA’s Air QUAlity TimE Series (EQUATES) project and their treatment in CRACMM to illustrate the mechanism coverage in carbon number, oxidation state, H:C, O:C, volatility, and reactivity space.