Reactive uptake of pinonaldehyde on acidic aerosols

Abstract

[1] The reactive uptake of pinonaldehyde, a monoterpene oxidation product, on aerosols has been studied in a reaction chamber. Monodisperse inorganic seed aerosols, consisting of acidic mixtures of (NH 4 ) 2 SO 4 and H 2 SO 4 , were exposed to gaseous pinonaldehyde for several hours within the chamber under relative humidity conditions of 3-65%. The aerosol inorganic and organic mass were quantitatively monitored in real time with an aerosol mass spectrometer (AMS) which also measured the mass spectra of the aerosols. Numerous fragments in the mass spectra were observed with masses greater than what can be accounted for by pinonaldehyde alone and have arisen from oligomerization in reactive uptake processes. The evolution of the mass spectra also revealed a progression toward larger oligomers over time. Significant organic mass was added to the aerosols in most experiments immediately upon exposure, resulting in maximum organic mass loadings from 3.5-110 mgm À3 depending on the experiments. Organic mass to seed aerosol SO 4 = ratios were also highly variable (0.06-4.75), resulting in particles ranging in composition from primarily inorganic to mostly organic. This reactive uptake was highly dependent upon the aerosol water activity, and hence acidity and did not occur on neutral (NH 4 ) 2 SO 4 aerosols suggesting that acidity is necessary. Reactive uptake coefficients (g) of pinonaldehyde were calculated by fitting a model of organic mass growth to the data. The coefficients spanned two orders of magnitude (1.2 Â 10 À5 -1.3 Â 10 À3 ) and were primarily dependent upon aerosol water activity and acidity but independent of gas phase pinonaldehyde concentrations. These coefficients indicated that the heterogeneous reactions of pinonaldehyde are of little importance as a gas phase loss mechanism but potentially of major importance as a source of secondary organic aerosols (SOA). Estimates of SOA production via pinonaldehyde, using the derived g, suggest that 1-750 ng m À3 of organic material can be formed in a short time, consistent with ambient measurements.

Reactive uptake of ammonia to secondary organic aerosols: kinetics of organonitrogen formation

“…At the present time, no data are available for comparison since the uptake kinetics of NH 3 on organic aerosol has not been reported. However, the uptake coefficients measured in this study are similar to those observed for glyoxal (Liggio et al, 2005a, b;Liggio and Li, 2006a), and are 2-4 orders of magnitude higher than biogenic olefins (Liggio and Li, 2008) and pinonaldehyde (Liggio and Li, 2006a) on acidic surfaces.…”

“…Secondary formation of particulate organics have also recently been considered another possible source of BrC through heterogeneous or multiphase chemical reactions Zarzana et al, 2012;Nguyen et al, 2013;Powelson et al, 2014), in which heteroatoms including O, S and N can be introduced into the particulate matter via a variety of precursors. For example, as characteristic components of HULIS (Nguyen et al, 2014, organosulfates and organonitrates have been observed in both laboratory generated (Liggio and Li, 2006b;Iinuma et al, 2009;Russell et al, 2011;Darer et al, 2011) and ambient organic particles (Hawkins et al, 2010;Surratt et al, 2006;Russell et al, 2011). Oxygen-and nitrogen-containing oligomers of high molecular weight have also been identified in secondary organic aerosols (SOA) (Kalberer et al, 2004).…”

“…ries of nitrogen atom (N) mass derived from the HR-ToF-AMS fragment families of C x H y N n , C x H y ON n , C x H y O 2 N n , NH x and NO x using an uptake model that has been described in detail previously (Liggio et al, 2005b;Liggio and Li, 2006a). Briefly, the change in the mass of N (within the NOC) added to a particle exposed to NH 3 as a function of time can be described by…”

Substantial secondary organic aerosol formation in a coniferous forest: observations of both day- and nighttime chemistry

“…Laboratory studies have also shown that some of the firstgeneration products of α-pinene ozonolysis can have a relatively high level of f 91 in their AMS spectra, including cis-pinonic acid droplets generated by atomization and pinonaldehyde uptake to sulfuric acid particles (Liggio and Li, 2006). Although cis-pinonic acid and pinonaldehyde are rather volatile, they may experience significant wall loss in smog chambers during the SOA formation experiments previously reported (Müller et al, 2012;Zhang et al, 2015).…”

Regional Modeling of Aerosol Chemical Composition at the Puy de Dôme (France)

“…Un des paramètres sensibles régissant la production d'aérosol par ces voies est la proportion d'acide sulfurique dans la particule. Pour exemple, Liggio and Li (2006a ;2006b) ont montré qu'un des produits d'oxydation de l'α-pinène, le pinonaldéhyde, contribuait d'autant plus à la formation de matière organique dans l'aérosol que le milieu était acide.…”