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| Titel |
Naphthalene SOA: redox activity and naphthoquinone gas–particle partitioning |
| VerfasserIn |
R. D. McWhinney, S. Zhou, J. P. D. Abbatt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 19 ; Nr. 13, no. 19 (2013-10-02), S.9731-9744 |
| Datensatznummer |
250085728
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| Publikation (Nr.) |
 copernicus.org/acp-13-9731-2013.pdf |
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| Zusammenfassung |
| Chamber secondary organic aerosol (SOA) from low-NOx photooxidation
of naphthalene by hydroxyl radical was examined with respect to its redox
cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was
highly redox-active, consuming DTT at an average rate of 118 ± 14 pmol
per minute per μg of SOA material. Measured particle-phase masses
of the major previously identified redox active products, 1,2- and
1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox
cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was
identified as a new minor product of naphthalene oxidation, and including
this species in redox activity predictions increased the predicted DTT
reactivity to 30 ± 5% of observations. These results suggest that
there are substantial unidentified redox-active SOA constituents beyond the
small quinones that may be important toxic components of these particles. A
gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ±
2.5) × 10−4 m3 μg−1 for 1,4-naphthoquinone at
25 °C. This value suggests that under typical warm conditions,
1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of
ambient particles, although further work is needed to determine the potential
impact under conditions such as low temperatures where partitioning to the
particle is more favourable. Also, higher order oxidation products that
likely account for a substantial fraction of the redox cycling capability of
the naphthalene SOA are likely to partition much more strongly to the
particle phase. |
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