title: Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling.
abstract: Cloudwater and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry (HRMS) with nanospray desorption electrospray ionization (nano-DESI) and direct infusion electrospray ionization (ESI) were utilized to compare the organic composition of the particle and cloudwater samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloudwater, showing the significant influence of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloudwater samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloudwater when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.
authors.affiliation: †Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Boone
authors.affiliation: ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
authors.forename: Alexander
authors.initials: A
authors.lastname: Laskin
authors.affiliation: §Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
authors.forename: Julia
authors.initials: J
authors.lastname: Laskin
authors.forename: Christopher
authors.initials: C
authors.lastname: Wirth
authors.forename: Paul B
authors.initials: PB
authors.lastname: Shepson
authors.affiliation: ∇Department of Aviation Technology, Purdue University, West Lafayette, Indiana 47907, United States.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Stirm
authors.affiliation: †Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.|○Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Kerri A
authors.initials: KA
authors.lastname: Pratt
mesh_terms: D000336:Aerosols / Q000032:analysis* / Q000737:chemistry; D000401:Aircraft; D000407:Alabama; D002070:Butadienes / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods*; D045782:Hemiterpenes / Q000737:chemistry; D006868:Hydrolysis; D013058:Mass Spectrometry / Q000379:methods; D039821:Monoterpenes / Q000737:chemistry; D017672:Nitrogen Compounds / Q000032:analysis / Q000737:chemistry; D052638:Particulate Matter / Q000032:analysis* / Q000737:chemistry; D010420:Pentanes / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013431:Sulfates / Q000032:analysis / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000336:Aerosols; D002070:Butadienes; D045782:Hemiterpenes; D039821:Monoterpenes; D017672:Nitrogen Compounds; D052638:Particulate Matter; D010420:Pentanes; D013431:Sulfates; D014867:Water; C005059:isoprene