| Autor: |
Pereira, Kelly L.1, Hamilton, Jacqueline F.1 jacqui.hamilton@york.ac.uk, Rickard, Andrew R.1,2, Bloss, William J.3, Alam, Mohammed S.3, Camredon, Marie4, Ward, Martyn W.1, Wyche, Kevin P.5, Muñoz, Amalia6, Vera, Teresa6, Vázquez, Mónica6, Borrás, Esther6, Ródenas, Milagros6 |
| Předmět: |
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| Zdroj: |
Environmental Science & Technology. 11/17/2015, Vol. 49 Issue 22, p13168-13178. 11p. |
| Abstrakt: |
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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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