 |
| Titel |
Functionalization and fragmentation during ambient organic aerosol aging: application of the 2-D volatility basis set to field studies |
| VerfasserIn |
B. N. Murphy, N. M. Donahue, C. Fountoukis, M. Dall'Osto, C. O'Dowd, A. Kiendler-Scharr, S. N. Pandis |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 22 ; Nr. 12, no. 22 (2012-11-16), S.10797-10816 |
| Datensatznummer |
250011599
|
| Publikation (Nr.) |
 copernicus.org/acp-12-10797-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| Multigenerational oxidation chemistry of atmospheric organic compounds and
its effects on aerosol loadings and chemical composition is investigated by
implementing the Two-Dimensional Volatility Basis Set (2-D-VBS) in a
Lagrangian host chemical transport model. Three model formulations were
chosen to explore the complex interactions between functionalization and
fragmentation processes during gas-phase oxidation of organic compounds by
the hydroxyl radical. The base case model employs a conservative
transformation by assuming a reduction of one order of magnitude in
effective saturation concentration and an increase of oxygen content by one
or two oxygen atoms per oxidation generation. A second scheme simulates
functionalization in more detail using group contribution theory to estimate
the effects of oxygen addition to the carbon backbone on the compound
volatility. Finally, a fragmentation scheme is added to the detailed
functionalization scheme to create a functionalization-fragmentation
parameterization. Two condensed-phase chemistry pathways are also
implemented as additional sensitivity tests to simulate (1) heterogeneous
oxidation via OH uptake to the particle-phase and (2) aqueous-phase chemistry
of glyoxal and methylglyoxal. The model is applied to summer and winter
periods at three sites where observations of organic aerosol (OA) mass and
O:C were obtained during the European Integrated Project on Aerosol Cloud
Climate and Air Quality Interactions (EUCAARI) campaigns. The base case
model reproduces observed mass concentrations and O:C well, with fractional
errors (FE) lower than 55% and 25%, respectively. The detailed
functionalization scheme tends to overpredict OA concentrations, especially
in the summertime, and also underpredicts O:C by approximately a factor of
2. The detailed functionalization model with fragmentation agrees well with
the observations for OA concentration, but still underpredicts O:C. Both
heterogeneous oxidation and aqueous-phase processing have small effects on
OA levels but heterogeneous oxidation, as implemented here, does enhance O:C
by about 0.1. The different schemes result in very different fractional
attribution for OA between anthropogenic and biogenic sources. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|