title: Cloud and fog processing enhanced gas-to-particle partitioning of trimethylamine.
abstract: An aerosol time-of-flight mass spectrometer (ATOFMS) was used to detect trimethylamine (TMA) in 0.52-1.9 μm particles at urban and rural sites in Southern Ontario during the summer and winter of 2007. During the summer, TMA-containing particles were observed exclusively during high relative humidity or fog events at both the urban and rural sites. In the wintertime, greater concentrations of TMA-containing particles were linked to cloud processing of aerosol in air masses originating from over agricultural and livestock areas. A laboratory study revealed that, at high relative humidity (∼ 100%), gas phase TMA at concentrations ranging from 2 to 20,000 ppt partitions preferentially to acidic particles present in the ambient air. On the basis of the field and laboratory studies, it appears that gas phase TMA present in ambient air partitions onto pre-existing particles preferentially during periods of acidic cloud/fog processing, leading to the presence of TMA-containing particles in the 0.52-1.9 μm size range.
authors.affiliation: Southern Ontario Centre for Atmospheric Aerosol Research, University of Toronto, 200 College Street, Toronto, Ontario, Canada.
authors.forename: Peter J G
authors.initials: PJ
authors.lastname: Rehbein
authors.forename: Cheol-Heon
authors.initials: CH
authors.lastname: Jeong
authors.forename: Maygan L
authors.initials: ML
authors.lastname: McGuire
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Yao
authors.forename: Joel C
authors.initials: JC
authors.lastname: Corbin
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Evans
mesh_terms: D000336:Aerosols / Q000032:analysis / Q000737:chemistry; D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D001272:Atmosphere / Q000737:chemistry*; D007700:Kinetics; D008744:Methylamines / Q000032:analysis* / Q000737:chemistry; D044367:Phase Transition; D055668:Photochemical Processes; D014887:Weather
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D008744:Methylamines; C023336:trimethylamine