title: SOA formation from partitioning and heterogeneous reactions: model study in the presence of inorganic species.
abstract: A predictive model for secondary organic aerosol (SOA) formation by both partitioning and heterogeneous reactions was developed for SOA created from ozonolysis of alpha-pinene in the presence of preexisting inorganic seed aerosols. SOA was created in a 2 m3 polytetrafluoroethylene film indoor chamber under darkness. Extensive sets of SOA experiments were conducted varying humidity, inorganic seed compositions comprising of ammonium sulfate and sulfuric acid, and amounts of inorganic seed mass. SOA mass was decoupled into partitioning (OM(P)) and heterogeneous aerosol production (OM(H)). The reaction rate constant for OM(H) production was subdivided into three categories (fast, medium, and slow) to consider different reactivity of organic products for the particle phase heterogeneous reactions. The influence of particle acidity on reaction rates was treated in a previous semiempirical model. Model OM(H) was developed with medium and strong acidic seed aerosols, and then extrapolated to OM(H) in weak acidic conditions, which are more relevant to atmospheric aerosols. To demonstrate the effects of preexisting glyoxal derivatives (e.g., glyoxal hydrate and dimer) on OM(H), SOA was created with a seed mixture comprising of aqueous glyoxal and inorganic species. Our results show that heterogeneous SOA formation was also influenced by preexisting reactive glyoxal derivatives.
authors.affiliation: Department of Environmental Sciences and Engineering, CB# 7431, Rosenau Hall, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599, USA. mjang@email.unc.edu
authors.forename: Myoseon
authors.initials: M
authors.lastname: Jang
authors.forename: Nadine M
authors.initials: NM
authors.lastname: Czoschke
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Northcross
authors.forename: Gang
authors.initials: G
authors.lastname: Cao
authors.forename: David
authors.initials: D
authors.lastname: Shaof
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000392:Air Movements; D000393:Air Pollutants; D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D006037:Glyoxal / Q000032:analysis; D007287:Inorganic Chemicals / Q000032:analysis*; D007700:Kinetics; D015233:Models, Statistical; D010083:Oxidants, Photochemical; D010126:Ozone; D010316:Particle Size; D011138:Polytetrafluoroethylene / Q000032:analysis; D013997:Time Factors
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D007287:Inorganic Chemicals; D010083:Oxidants, Photochemical; D006037:Glyoxal; D010126:Ozone; D002244:Carbon; D011138:Polytetrafluoroethylene