Formation and aging of secondary organic aerosol from toluene: changes in chemical composition, volatility, and hygroscopicity
Secondary organic aerosol (SOA) is transformed after its initial formation, but this chemical aging of SOA is poorly understood. Experiments were conducted in the Carnegie Mellon environmental chamber to form secondary organic aerosol (SOA) from the photo-oxidation of toluene and other small aromati...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/15/8301/2015/acp-15-8301-2015.pdf |
| Summary: | Secondary organic aerosol (SOA) is transformed after its initial formation,
but this chemical aging of SOA is poorly understood. Experiments were
conducted in the Carnegie Mellon environmental chamber to form secondary
organic aerosol (SOA) from the photo-oxidation of toluene and other small
aromatic volatile organic compounds (VOCs) in the presence of NO<sub><i>x</i></sub> under
different oxidizing conditions. The effects of the oxidizing condition on
organic aerosol (OA) composition, mass yield, volatility, and hygroscopicity
were explored. Higher exposure to the hydroxyl radical resulted in different
OA composition, average carbon oxidation state (OS<sub>c</sub>), and mass yield. The OA oxidation state generally increased during
photo-oxidation, and the final OA OS<sub>c</sub> ranged from −0.29 to 0.16 in the performed experiments. The
volatility of OA formed in these different experiments varied by as much as
a factor of 30, demonstrating that the OA formed under different oxidizing
conditions can have a significantly different saturation concentration. There
was no clear correlation between hygroscopicity and oxidation state for this
relatively hygroscopic SOA. |
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| ISSN: | 1680-7316 1680-7324 |