Journal
ENVIRONMENTAL CHEMISTRY
Volume 9, Issue 3, Pages 211-220Publisher
CSIRO PUBLISHING
DOI: 10.1071/EN11162
Keywords
-
Categories
Funding
- Office of Energy Research, Office of Basic Energy Sciences, Chemical Sciences Division of the US Department of Energy [DE-AC02-05CH11231]
- Camille and Henry Dreyfus Foundation
Ask authors/readers for more resources
The oxidative aging of the semivolatile fraction of diesel exhaust aerosol is studied in order to better understand the influence of oxidation reactions on particle chemical composition. Exhaust is sampled from an idling diesel truck, sent through a denuder to remove gas-phase species and oxidised by hydroxyl (OH center dot) radicals in a flow reactor. OH center dot concentrations are chosen to approximately match the OH center dot exposures a particle would experience over its atmospheric lifetime. Evolving particle composition is monitored using aerosol mass spectrometry in two different modes, electron impact ionisation (EI) for the measurement of elemental ratios and vacuum ultraviolet (VUV) photoionisation for the measurement of molecular components. Changes to mass spectra in both modes indicate major changes to particle composition over the range of OH center dot exposures studied. The product aerosol is only lightly oxidised (O/C < 0.3), suggesting an intermediate oxidation state between primary organics and the highly oxidised organic aerosol observed in the atmosphere. These lightly oxidised organics appear to be composed of secondary organic aerosol from semivolatile species, as well as from heterogeneously oxidised particle-phase organics. Key chemical characteristics (elemental ratios, oxidation kinetics and mass spectrometric features) of the reaction system are examined in detail. Similarities between this laboratory-generated aerosol and 'hydrocarbon-like organic aerosol' (HOA) reported in ambient studies suggest that HOA might not be entirely primary in origin, as is commonly assumed, but rather might include a significant secondary component.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available