title: Insights into the Formation and Evolution of Individual Compounds in the Particulate Phase during Aromatic Photo-Oxidation.
abstract: Secondary organic aerosol (SOA) is well-known to have adverse effects on air quality and human health. However, the dynamic mechanisms occurring during SOA formation and evolution are poorly understood. The time-resolved SOA composition formed during the photo-oxidation of three aromatic compounds, methyl chavicol, toluene and 4-methyl catechol, were investigated at the European Photoreactor. SOA was collected using a particle into liquid sampler and analyzed offline using state-of-the-art mass spectrometry to produce temporal profiles of individual photo-oxidation products. In the photo-oxidation of methyl chavicol, 70 individual compounds were characterized and three distinctive temporal profile shapes were observed. The calculated mass fraction (Ci,aer/COA) of the individual SOA compounds showed either a linear trend (increasing/decreasing) or exponential decay with time. Substituted nitrophenols showed an exponential decay, with the nitro-group on the aromatic ring found to control the formation and loss of these species in the aerosol phase. Nitrophenols from both methyl chavicol and toluene photo-oxidation experiments showed a strong relationship with the NO2/NO (ppbv/ppbv) ratio and were observed during initial SOA growth. The location of the nitrophenol aromatic substitutions was found to be critically important, with the nitrophenol in the photo-oxidation of 4-methyl catechol not partitioning into the aerosol phase until irradiation had stopped; highlighting the importance of studying SOA formation and evolution at a molecular level.
authors.affiliation: Wolfson Atmospheric Chemistry Laboratory, Department of Chemistry, University of York , York, YO10 5DD, United Kingdom.
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Pereira
authors.affiliation: Wolfson Atmospheric Chemistry Laboratory, Department of Chemistry, University of York , York, YO10 5DD, United Kingdom.
authors.forename: Jacqueline F
authors.initials: JF
authors.lastname: Hamilton
authors.affiliation: Wolfson Atmospheric Chemistry Laboratory, Department of Chemistry, University of York , York, YO10 5DD, United Kingdom.|National Centre for Atmospheric Science, University of York , York, YO10 5DD, United Kingdom.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Rickard
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham, B15 2TT, United Kingdom.
authors.forename: William J
authors.initials: WJ
authors.lastname: Bloss
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham, B15 2TT, United Kingdom.
authors.forename: Mohammed S
authors.initials: MS
authors.lastname: Alam
authors.affiliation: LISA, UMR CNRS/INSU 7583, University of Paris-Est Créteil and Paris Diderot , Créteil, 94010, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Camredon
authors.affiliation: Wolfson Atmospheric Chemistry Laboratory, Department of Chemistry, University of York , York, YO10 5DD, United Kingdom.
authors.forename: Martyn W
authors.initials: MW
authors.lastname: Ward
authors.affiliation: Air Environment Research, School Environment and Technology, University of Brighton , Brighton, BN2 4AT, United Kingdom.
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Wyche
authors.affiliation: CEAM-UMH, EUPHORE, Valencia, 46980, Spain.
authors.forename: Amalia
authors.initials: A
authors.lastname: Muñoz
authors.affiliation: CEAM-UMH, EUPHORE, Valencia, 46980, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Vera
authors.affiliation: CEAM-UMH, EUPHORE, Valencia, 46980, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Vázquez
authors.affiliation: CEAM-UMH, EUPHORE, Valencia, 46980, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Borrás
authors.affiliation: CEAM-UMH, EUPHORE, Valencia, 46980, Spain.
authors.forename: Milagros
authors.initials: M
authors.lastname: Ródenas
mesh_terms: D000081248:Allylbenzene Derivatives; D000840:Anisoles / Q000737:chemistry; D001272:Atmosphere / Q000737:chemistry; D006813:Humidity; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D008027:Light; D009596:Nitrophenols / Q000032:analysis; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction / Q000528:radiation effects; D052638:Particulate Matter / Q000032:analysis*; D013696:Temperature; D013997:Time Factors; D014050:Toluene / Q000737:chemistry; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D000081248:Allylbenzene Derivatives; D000840:Anisoles; D006841:Hydrocarbons, Aromatic; D009596:Nitrophenols; D016877:Oxidants; D052638:Particulate Matter; D055549:Volatile Organic Compounds; D014050:Toluene; C007633:estragole