Relating hygroscopicity and composition of organic aerosol particulate matter

Journal Article · Sat Jan 01 00:00:00 EST 2011 · Atmospheric Chemistry and Physics (Online)

DOI:https://doi.org/10.5194/acp-11-1155-2011· OSTI ID:1015256

Duplissy, J.; DeCarlo, P. F.; Dommen, J.; Alfarra, M. R.; Metzger, A.; Barmpadimos, I.; Prevot, A. S. H.; Weingartner, E.; Tritscher, T.; Gysel, M.; Aiken, A. C.; Jimenez, J. L.; Canagaratna, M. R.; Worsnop, D. R.; Collins, D. R.; Tomlinson, J.; Baltensperger, U.

A hygroscopicity tandem differential mobility analyzer (HTDMA) was used to measure the water uptake (hygroscopicity) of secondary organic aerosol (SOA) formed during the chemical and photochemical oxidation of several organic precursors in a smog chamber. Electron ionization mass spectra of the non-refractory submicron aerosol were simultaneously determined with an aerosol mass spectrometer (AMS), and correlations between the two different signals were investigated. SOA hygroscopicity was found to strongly correlate with the relative abundance of the ion signal m/z 44 expressed as a fraction of total organic signal (f₄₄). m/z 44 is due mostly to the ion fragment CO₂⁺ for all types of SOA systems studied, and has been previously shown to strongly correlate with organic O/C for ambient and chamber OA. The analysis was also performed on ambient OA from two field experiments at the remote site Jungfraujoch, and the megacity Mexico City, where similar results were found. A simple empirical linear relation between the hygroscopicity of OA at subsaturated RH, as given by the hygroscopic growth factor (GF) or "κ_org" parameter, and f₄₄ was determined and is given by κ_org = 2.2 × f₄₄ - 0.13. This approximation can be further verified and refined as the database for AMS and HTDMA measurements is constantly being expanded around the world. Finally, the use of this approximation could introduce an important simplification in the parameterization of hygroscopicity of OA in atmospheric models, since f₄₄ is correlated with the photochemical age of an air mass.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1015256
• Report Number(s): PNNL-SA-75359; KP1704010; TRN: US201111%%516
• Journal Information: Atmospheric Chemistry and Physics (Online), Vol. 11, Issue 3; ISSN 1680-7324
• Publisher: European Geosciences Union
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ABUNDANCE
AEROSOLS
AIR
APPROXIMATIONS
ELECTRONS
GROWTH FACTORS
HYGROSCOPICITY
IONIZATION
MASS SPECTRA
MASS SPECTROMETERS
MEXICO
OXIDATION
PARTICULATES
SMOG
WATER