title: Insights into secondary organic aerosol formation mechanisms from measured gas/particle partitioning of specific organic tracer compounds.
abstract: In situ measurements of organic compounds in both gas and particle phases were made with a thermal desorption aerosol gas chromatography (TAG) instrument. The gas/particle partitioning of phthalic acid, pinonaldehyde, and 6,10,14-trimethyl-2-pentadecanone is discussed in detail to explore secondary organic aerosol (SOA) formation mechanisms. Measured fractions in the particle phase (f(part)) of 6,10,14-trimethyl-2-pentadecanone were similar to those expected from the absorptive gas/particle partitioning theory, suggesting that its partitioning is dominated by absorption processes. However, f(part) of phthalic acid and pinonaldehyde were substantially higher than predicted. The formation of low-volatility products from reactions of phthalic acid with ammonia is proposed as one possible mechanism to explain the high f(part) of phthalic acid. The observations of particle-phase pinonaldehyde when inorganic acids were fully neutralized indicate that inorganic acids are not required for the occurrence of reactive uptake of pinonaldehyde on particles. The observed relationship between f(part) of pinonaldehyde and relative humidity suggests that the aerosol water plays a significant role in the formation of particle-phase pinonaldehyde. Our results clearly show it is necessary to include multiple gas/particle partitioning pathways in models to predict SOA and multiple SOA tracers in source apportionment models to reconstruct SOA.
authors: Department of Environmental Science, Policy and Management, University of California, Berkeley, California, USA.
authors: Yunliang
authors: Y
authors: Zhao
authors: Nathan M
authors: NM
authors: Kreisberg
authors: David R
authors: DR
authors: Worton
authors: Gabriel
authors: G
authors: Isaacman
authors: Robin J
authors: RJ
authors: Weber
authors: Shang
authors: S
authors: Liu
authors: Douglas A
authors: DA
authors: Day
authors: Lynn M
authors: LM
authors: Russell
authors: Milos Z
authors: MZ
authors: Markovic
authors: Trevor C
authors: TC
authors: VandenBoer
authors: Jennifer G
authors: JG
authors: Murphy
authors: Susanne V
authors: SV
authors: Hering
authors: Allen H
authors: AH
authors: Goldstein
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000447:Aldehydes; D000838:Anions / Q000032:analysis; D002244:Carbon / Q000032:analysis; D002412:Cations / Q000032:analysis; D002849:Chromatography, Gas; D003503:Cyclobutanes; D005740:Gases / Q000032:analysis*; D007659:Ketones / Q000032:analysis; D009930:Organic Chemicals / Q000032:analysis*; D010100:Oxygen / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis*; D010795:Phthalic Acids; D013997:Time Factors; D055548:Vapor Pressure
chemical_list: C447863:2,2-dimethyl-3-acetyl-cyclobutyl-ethanal; D000336:Aerosols; D000447:Aldehydes; D000838:Anions; D002412:Cations; D003503:Cyclobutanes; D005740:Gases; D007659:Ketones; D009930:Organic Chemicals; D052638:Particulate Matter; D010795:Phthalic Acids; C032279:phthalic acid; D002244:Carbon; D010100:Oxygen