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- ItemTerpenylic acid and related compounds: precursors for dimers in secondary organic aerosol from the ozonolysis of α- and β-pinene(München : European Geopyhsical Union, 2010) Yasmeen, F.; Vermeylen, R.; Szmigielski, R.; Iinuma, Y.; Böge, O.; Herrmann, H.; Maenhaut, W.; Claeys, M.In the present study, we have characterized the structure of a higher-molecular weight (MW) 358 α- and β-pinene dimeric secondary organic aerosol (SOA) product that received ample attention in previous molecular characterization studies and has been elusive. Based on mass spectrometric evidence for deprotonated molecules formed by electrospray ionization in the negative ion mode and chemical considerations, it is suggested that diaterpenylic acid is a key monomeric intermediate for dimers of the ester type. It is proposed that cis-pinic acid is esterified with the hydroxyl-containing diaterpenylic acid, which can be explained through acid-catalyzed hydrolysis of the recently elucidated lactone-containing terpenylic acid and/or diaterpenylic acid acetate, both first-generation oxidation products. To a minor extent, higher-MW 358 and 344 diester products are formed containing other terpenoic acids as monomeric units, i.e., diaterpenylic acid instead of cis-pinic acid, and diaterebic acid instead of diaterpenylic acid. It is shown that the MW 358 diester and related MW 344 compounds, which can be regarded as processed SOA products, also occur in ambient fine (PM2.5) rural aerosol collected at night during the warm period of the 2006 summer field campaign conducted at K-puszta, Hungary, a rural site with coniferous vegetation. This indicates that, under ambient conditions, the higher-MW diesters are formed in the particle phase over a longer time-scale than that required for gas-to-particle partitioning of their monomeric precursors in laboratory α-/β-pinene ozonolysis experiments.
- ItemThe formation, properties and impact of secondary organic aerosol: Current and emerging issues(München : European Geopyhsical Union, 2009) Hallquist, M.; Wenger, J.C.; Baltensperger, U.; Rudich, Y.; Simpson, D.; Claeys, M.; Dommen, J.; Donahue, N.M.; George, C.; Goldstein, A.; Hamilton, J.F.; Herrmann, H.; Hoffmann, T.; Iinuma, Y.; Jang, M.; Jenkin, M.E.; Jimenez, J.L.; Kiendler-Scharr, A.; Maenhaut, W.; McFiggans, G.; Mentel, Th.F.; Monod, A.; Prévôt, A.S.H.; Seinfeld, J.H.; Surratt, J.D.; Szmigielski, R.; Wildt, J.Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol and a detailed knowledge of the formation, properties and transformation of SOA is therefore required to evaluate its impact on atmospheric processes, climate and human health. The chemical and physical processes associated with SOA formation are complex and varied, and, despite considerable progress in recent years, a quantitative and predictive understanding of SOA formation does not exist and therefore represents a major research challenge in atmospheric science. This review begins with an update on the current state of knowledge on the global SOA budget and is followed by an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and the analytical techniques used to determine the chemical composition of SOA. A survey of recent laboratory, field and modeling studies is also presented. The following topical and emerging issues are highlighted and discussed in detail: molecular characterization of biogenic SOA constituents, condensed phase reactions and oligomerization, the interaction of atmospheric organic components with sulfuric acid, the chemical and photochemical processing of organics in the atmospheric aqueous phase, aerosol formation from real plant emissions, interaction of atmospheric organic components with water, thermodynamics and mixtures in atmospheric models. Finally, the major challenges ahead in laboratory, field and modeling studies of SOA are discussed and recommendations for future research directions are proposed.
- ItemAn intercomparison study of analytical methods used for quantification of levoglucosan in ambient aerosol filter samples(München : European Geopyhsical Union, 2015) Yttri, K.E.; Schnelle-Kreis, J.; Maenhaut, W.; Abbaszade, G.; Alves, C.; Bjerke, A.; Bonnier, N.; Bossi, R.; Claeys, M.; Dye, C.; Evtyugina, M.; García-Gacio, D.; Hillamo, R.; Hoffer, A.; Hyder, M.; Iinuma, Y.; Jaffrezo, J.-L.; Kasper-Giebl, A.; Kiss, G.; López-Mahia, P.L.; Pio, C.; Piot, C.; Ramirez-Santa-Cruz, C.; Sciare, J.; Teinilä, K.; Vermeylen, R.; Vicente, A.; Zimmermann, R.The monosaccharide anhydrides (MAs) levoglucosan, galactosan and mannosan are products of incomplete combustion and pyrolysis of cellulose and hemicelluloses, and are found to be major constituents of biomass burning (BB) aerosol particles. Hence, ambient aerosol particle concentrations of levoglucosan are commonly used to study the influence of residential wood burning, agricultural waste burning and wildfire emissions on ambient air quality. A European-wide intercomparison on the analysis of the three monosaccharide anhydrides was conducted based on ambient aerosol quartz fiber filter samples collected at a Norwegian urban background site during winter. Thus, the samples' content of MAs is representative for BB particles originating from residential wood burning. The purpose of the intercomparison was to examine the comparability of the great diversity of analytical methods used for analysis of levoglucosan, mannosan and galactosan in ambient aerosol filter samples. Thirteen laboratories participated, of which three applied high-performance anion-exchange chromatography (HPAEC), four used high-performance liquid chromatography (HPLC) or ultra-performance liquid chromatography (UPLC) and six resorted to gas chromatography (GC). The analytical methods used were of such diversity that they should be considered as thirteen different analytical methods. All of the thirteen laboratories reported levels of levoglucosan, whereas nine reported data for mannosan and/or galactosan. Eight of the thirteen laboratories reported levels for all three isomers. The accuracy for levoglucosan, presented as the mean percentage error (PE) for each participating laboratory, varied from −63 to 20%; however, for 62% of the laboratories the mean PE was within ±10%, and for 85% the mean PE was within ±20%. For mannosan, the corresponding range was −60 to 69%, but as for levoglucosan, the range was substantially smaller for a subselection of the laboratories; i.e. for 33% of the laboratories the mean PE was within ±10%. For galactosan, the mean PE for the participating laboratories ranged from −84 to 593%, and as for mannosan 33% of the laboratories reported a mean PE within ±10%. The variability of the various analytical methods, as defined by their minimum and maximum PE value, was typically better for levoglucosan than for mannosan and galactosan, ranging from 3.2 to 41% for levoglucosan, from 10 to 67% for mannosan and from 6 to 364% for galactosan. For the levoglucosan to mannosan ratio, which may be used to assess the relative importance of softwood versus hardwood burning, the variability only ranged from 3.5 to 24 . To our knowledge, this is the first major intercomparison on analytical methods used to quantify monosaccharide anhydrides in ambient aerosol filter samples conducted and reported in the scientific literature. The results show that for levoglucosan the accuracy is only slightly lower than that reported for analysis of SO42- (sulfate) on filter samples, a constituent that has been analysed by numerous laboratories for several decades, typically by ion chromatography and which is considered a fairly easy constituent to measure. Hence, the results obtained for levoglucosan with respect to accuracy are encouraging and suggest that levels of levoglucosan, and to a lesser extent mannosan and galactosan, obtained by most of the analytical methods currently used to quantify monosaccharide anhydrides in ambient aerosol filter samples, are comparable. Finally, the various analytical methods used in the current study should be tested for other aerosol matrices and concentrations as well, the most obvious being summertime aerosol samples affected by wildfires and/or agricultural fires.