title: Heterogeneous reactions of particulate matter-bound PAHs and NPAHs with NO3/N2O5, OH radicals, and O3 under simulated long-range atmospheric transport conditions: reactivity and mutagenicity.
abstract: The heterogeneous reactions of ambient particulate matter (PM)-bound polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) with NO3/N2O5, OH radicals, and O3 were studied in a laboratory photochemical chamber. Ambient PM2.5 and PM10 samples were collected from Beijing, China, and Riverside, California, and exposed under simulated atmospheric long-range transport conditions for O3 and OH and NO3 radicals. Changes in the masses of 23 PAHs and 20 NPAHs, as well as the direct and indirect-acting mutagenicity of the PM (determined using the Salmonella mutagenicity assay with TA98 strain), were measured prior to and after exposure to NO3/N2O5, OH radicals, and O3. In general, O3 exposure resulted in the highest relative degradation of PM-bound PAHs with more than four rings (benzo[a]pyrene was degraded equally well by O3 and NO3/N2O5). However, NPAHs were most effectively formed during the Beijing PM exposure to NO3/N2O5. In ambient air, 2-nitrofluoranthene (2-NF) is formed from the gas-phase NO3 radical- and OH radical-initiated reactions of fluoranthene, and 2-nitropyrene (2-NP) is formed from the gas-phase OH radical-initiated reaction of pyrene. There was no formation of 2-NF or 2-NP in any of the heterogeneous exposures, suggesting that gas-phase formation of NPAHs did not play an important role during chamber exposures. Exposure of Beijing PM to NO3/N2O5 resulted in an increase in direct-acting mutagenic activity which was associated with the formation of mutagenic NPAHs. No NPAH formation was observed in any of the exposures of the Riverside PM. This was likely due to the accumulation of atmospheric degradation products from gas-phase reactions of volatile species onto the surface of PM collected in Riverside prior to exposure in the chamber, thus decreasing the availability of PAHs for reaction.
authors.affiliation: Department of Chemistry, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Narumol
authors.initials: N
authors.lastname: Jariyasopit
authors.forename: Kathryn
authors.initials: K
authors.lastname: Zimmermann
authors.forename: Jill
authors.initials: J
authors.lastname: Schrlau
authors.forename: Janet
authors.initials: J
authors.lastname: Arey
authors.forename: Roger
authors.initials: R
authors.lastname: Atkinson
authors.forename: Tian-Wei
authors.initials: TW
authors.lastname: Yu
authors.forename: Roderick H
authors.initials: RH
authors.lastname: Dashwood
authors.forename: Shu
authors.initials: S
authors.lastname: Tao
authors.forename: Staci L Massey
authors.initials: SL
authors.lastname: Simonich
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D002140:California; D002681:China; D005449:Fluorenes / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D009152:Mutagenicity Tests; D009153:Mutagens / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D052638:Particulate Matter / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D011721:Pyrenes / Q000737:chemistry
chemical_list: D005449:Fluorenes; D009153:Mutagens; D009566:Nitrates; D009589:Nitrogen Oxides; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; D017665:Hydroxyl Radical; D010126:Ozone; C010125:nitrogen pentoxide; C049029:2-nitropyrene; C049030:2-nitrofluoranthene