Understanding primary and secondary sources of ambient carbonyl compounds in Beijing using the PMF model
Carbonyl compounds are important intermediates in atmospheric photochemistry. To explore the relative contributions of primary and secondary carbonyl sources, carbonyls and other volatile organic compounds (VOCs) were measured at an urban site in both winter and summer in Beijing. The positive matri...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/14/3047/2014/acp-14-3047-2014.pdf |
| Summary: | Carbonyl compounds are important intermediates in atmospheric
photochemistry. To explore the relative contributions of primary and
secondary carbonyl sources, carbonyls and other volatile organic compounds
(VOCs) were measured at an urban site in both winter and summer in Beijing.
The positive matrix factorization (PMF) model was used for source
apportionment of VOCs. As VOCs undergo photochemical processes in the
atmosphere, and such processes may interfere with factor identification, the
relationships between the contributions of the resolved PMF factors to each
non-methane hydrocarbon (NMHC) species and its <i>k</i><sub>OH</sub> value were used to
distinguish fresh factors and photochemically aged factors. As the result of
PMF, five factors were resolved in winter, and two of them were identified
as photochemically aged emissions. In summer, four factors were resolved,
including one aged factor. Carbonyls abundances from aged factors were
simulated by VOCs consumption and the corresponding carbonyl production
yields, and the simulated abundances agreed well with the results obtained
by the PMF model. The source apportionment results indicated that secondary
formation was the major source of carbonyls in both winter and summer, with
the respective contributions of 51.2% and 46.0%. For the three major
carbonyl species, primary anthropogenic sources contributed 28.9% and
32.3% to ambient formaldehyde, 53.7% and 41.6% to acetaldehyde,
68.1% and 56.2% to acetone in winter and summer, respectively. |
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| ISSN: | 1680-7316 1680-7324 |