ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-4377-2010 A global perspective on aerosol from low-volatility organic compounds Pye H. O. T. 1 Seinfeld J. H. 1 Department of Chemical Engineering, California Institute of Technology, Pasadena, CA, USA 12 05 2010 10 9 4377 4401 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/10/4377/2010/acp-10-4377-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/4377/2010/acp-10-4377-2010.pdf

Global production of organic aerosol from primary emissions of semivolatile (SVOCs) and intermediate (IVOCs) volatility organic compounds is estimated using the global chemical transport model, GEOS-Chem. SVOC oxidation is predicted to be a larger global source of net aerosol production than oxidation of traditional parent hydrocarbons (terpenes, isoprene, and aromatics). Using a prescribed rate constant and reduction in volatility for atmospheric oxidation, the yield of aerosol from SVOCs is predicted to be about 75% on a global, annually-averaged basis. For IVOCs, the use of a naphthalene-like surrogate with different high-NO<sub>x</sub> and low-NO<sub>x</sub> parameterizations produces a global aerosol yield of about 30%, or roughly 5 Tg/yr of aerosol. Estimates of the total global organic aerosol source presented here range between 60 and 100 Tg/yr. This range reflects uncertainty in the parameters for SVOC volatility, SVOC oxidation, SVOC emissions, and IVOC emissions, as well as wet deposition. The highest estimates result if SVOC emissions are significantly underestimated (by more than a factor of 2) or if wet deposition of the gas-phase semivolatile species is less effective than previous estimates. A significant increase in SVOC emissions, a reduction of the volatility of the SVOC emissions, or an increase in the enthalpy of vaporization of the organic aerosol all lead to an appreciable reduction of prediction/measurement discrepancy. In addition, if current primary organic aerosol (POA) inventories capture only about one-half of the SVOC emission and the Henrys Law coefficient for oxidized semivolatiles is on the order of 10<sup>3</sup> M/atm, a global estimate of OA production is not inconsistent with the top-down estimate of 140 Tg/yr by (Goldstein and Galbally, 2007). Additional information is needed to constrain the emissions and treatment of SVOCs and IVOCs, which have traditionally not been included in models.

 References Aiken, A C., Decarlo, P F., Kroll, J H., Worsnop, D R., Huffman, J A., Docherty, K S., Ulbrich, I M., Mohr, C., Kimmel, J R., Sueper, D., Sun, Y., Zhang, Q., Trimborn, A., Northway, M., Ziemann, P J., Canagaratna, M R., Onasch, T B., Alfarra, M R., Prevot, A. S H., Dommen, J., Duplissy, J., Metzger, A., Baltensperger, U., and Jimenez, J L.: O/C and OM/OC ratios of primary, secondary, and ambient organic aerosols with high-resolution time-of-flight aerosol mass spectrometry, Environ. Sci. Technol., 42, 4478–4485, \doi10.1021/ES703009q, 2008. Andreae, M O. and Merlet, P.: Emission of trace gases and aerosols from biomass burning, Global Biogeochem. Cy., 15, 955–966, \doi10.1029/2000GB001382, 2001. Archibald, A T., Jenkin, M E., and Shallcross, D E.: An isoprene mechanism intercomparison, Atmos. Environ., \doi10.1016/J.ATMOSENV.2009.09.016, in press, 2010. Atkinson, R.: Gas-phase tropospheric chemistry of volatile organic compounds: 1. Alkanes and alkenes, J. Phys. Chem. Ref. Data, 26, 215–290, 1997. Atkinson, R. and Arey, J.: Atmospheric degration of volatile organic compounds, Chem. Rev., 103, 4605–4638, \doi10.1021/CR0206420, 2003. Bench, G., Fallon, S., Schichtel, B., Malm, W., and McDade, C.: Relative contributions of fossil and contemporary carbon sources to \chemPM_2.5 aerosols at nine Interagency Monitoring for Protection of Visual Environments (IMPROVE) network sites, J. Geophys. Res., 112, D10205, \doi10.1029/2006JD007708, 2007. Bey, I., Jacob, D J., Yantosca, R M., Logan, J A., Field, B D., Fiore, A M., Li, Q B., Liu, H. G Y., Mickley, L J., and Schultz, M G.: Global modeling of tropospheric chemistry with assimilated meteorology: Model description and evaluation, J. Geophys. Res., 106, 23073–23095, 2001. Bhave, P. V., Pouliot, G. A., and Zheng, M.: Diagnostic model evaluation for carbonaceous PM$_2.5$ using organic markers measured in the southeastern U.S., Environ. Sci. Technol., 41, 1577–1583, 2007. Bond, T C., Streets, D G., Yarber, K F., Nelson, S M., Woo, J H., and Klimont, Z.: A technology-based global inventory of black and organic carbon emissions from combustion, J. Geophys. Res., 109, D14203, \doi10.1029/2003JD003697, 2004. Butler, T. M., Taraborrelli, D., Brühl, C., Fischer, H., Harder, H., Martinez, M., Williams, J., Lawrence, M. G., and Lelieveld, J.: Improved simulation of isoprene oxidation chemistry with the ECHAM5/MESSy chemistry-climate model: lessons from the GABRIEL airborne field campaign, Atmos. Chem. Phys., 8, 4529–4546, doi:10.5194/acp-8-4529-2008, 2008. Cappa, C. D. and Jimenez, J. L.: Quantitative estimates of the volatility of ambient organic aerosol, Atmos. Chem. Phys. Discuss., 10, 1901–1938, doi:10.5194/acpd-10-1901-2010, 2010. Chan, A. W. H., Kautzman, K. E., Chhabra, P. S., Surratt, J. D., Chan, M. N., Crounse, J. D., Kürten, A., Wennberg, P. O., Flagan, R. C., and Seinfeld, J. H.: Secondary organic aerosol formation from photooxidation of naphthalene and alkylnaphthalenes: implications for oxidation of intermediate volatility organic compounds (IVOCs), Atmos. Chem. Phys., 9, 3049–3060, doi:10.5194/acp-9-3049-2009, 2009. Chhabra, P. S., Flagan, R. C., and Seinfeld, J. H.: Elemental analysis of chamber organic aerosol using an aerodyne high-resolution aerosol mass spectrometer, Atmos. Chem. Phys., 10, 4111–4131, doi:10.5194/acp-10-4111-2010, 2010. Chung, S H. and Seinfeld, J H.: Global distribution and climate forcing of carbonaceous aerosols, J. Geophys. Res., 107, 4407, \doi10.1029/2001JD001397, 2002. Cooke, W F., Liousse, C., Cachier, H., and Feichter, J.: Construction of a $1\degree\times1\degree$ fossil fuel emission data set for carbonaceous aerosol and implementation and radiative impact in the ECHAM4 model, J. Geophys. Res., 104, 22137–22162, 1999. de Gouw, J. A., Middlebrook, A. M., Warneke, C., Goldan, P. D., Kuster, W. C., Roberts, J. M., Fehsenfeld, F. C., Worsnop, D. R., Canagaratna, M. R., Pszenny, A. A. P., Keene, W. C., Marchewka, M., Bertman, S. B., and Bates, T. S.: Budget of organic carbon in a polluted atmosphere: Results from the New England Air Quality Study in 2002, J. Geophys. Res., 110, D16305, \doi10.1029/2004JD005623, 2005. Donahue, N M., Robinson, A L., Stanier, C O., and Pandis, S N.: Coupled partitioning, dilution, and chemical aging of semivolatile organics, Environ. Sci. Technol., 40, 2635–2643, \doi10.1021/ES052297c, 2006. Dzepina, K., Volkamer, R. M., Madronich, S., Tulet, P., Ulbrich, I. M., Zhang, Q., Cappa, C. D., Ziemann, P. J., and Jimenez, J. L.: Evaluation of recently-proposed secondary organic aerosol models for a case study in Mexico City, Atmos. Chem. Phys., 9, 5681–5709, doi:10.5194/acp-9-5681-2009, 2009. Epstein, S. A., Riipinen, I., and Donahue, N. M.: A semiempirical correlation between enthalpy of vaporization and saturation concentration for organic aerosol, Environ. Sci. Technol., 44, 743–748, \doi10.1021/ES902497z, 2010. Farina, S C., Adams, P J., and Pandis, S N.: Modeling global secondary organic aerosol formation and processing with the volatility basis set: implications for anthropogenic SOA, J. Geophys. Res., \doi10.1029/2009JD013046, 115, D09202, doi:10.1029/2009JD013046, 2010. Fu, T M., Jacob, D J., Wittrock, F., Burrows, J P., Vrekoussis, M., and Henze, D K.: Global budgets of atmospheric glyoxal and methylglyoxal, and implications for formation of secondary organic aerosols, J. Geophys. Res., 113, D15303, \doi10.1029/2007JD009505, 2008. Goldstein, A H. and Galbally, I E.: Known and unexplored organic constituents in the earth's atmosphere, Environ. Sci. Technol., 41, 1514–1521, \doi10.1021/ES072476p, 2007. Grieshop, A. P., Logue, J. M., Donahue, N. M., and Robinson, A. L.: Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 1: measurement and simulation of organic aerosol evolution, Atmos. Chem. Phys., 9, 1263-1277, doi:10.5194/acp-9-1263-2009, 2009. Grieshop, A P., Miracolo, M A., Donahue, N M., and Robinson, A L.: Constraining the volatility distribution and gas-particle partitioning of combustion aerosols using isothermal dilution and thermodenuder measurements, Environ. Sci. Technol., 43, 4750–4756, \doi10.1021/ES8032378, 2009b. Guenther, A., Hewitt, C N., Erickson, D., Fall, R., Geron, C., Graedel, T., Harley, P., Klinger, L., Lerdau, M., Mckay, W A., Pierce, T., Scholes, B., Steinbrecher, R., Tallamraju, R., Taylor, J., and Zimmerman, P.: A global-model of natural volatile organic-compound emissions, J. Geophys. Res., 100, 8873–8892, 1995. Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P. I., and Geron, C.: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys., 6, 3181–3210, doi:10.5194/acp-6-3181-2006, 2006. Hays, M D., Geron, C D., Linna, K J., Smith, N D., and Schauer, J J.: Speciation of gas-phase and fine particle emissions from burning of foliar fuels, Environ. Sci. Technol., 36, 2281–2295, \doi10.1021/ES0111683, 2002. Heald, C L., Jacob, D J., Park, R J., Russell, L M., Huebert, B J., Seinfeld, J H., Liao, H., and Weber, R J.: A large organic aerosol source in the free troposphere missing from current models, Geophys. Res. Lett., 32, L18809, \doi10.1029/2005GL023831, 2005. Henze, D K. and Seinfeld, J H.: Global secondary organic aerosol from isoprene oxidation, Geophys. Res. Lett., 33, \doi10.1029/2006GL025976, 2006. Henze, D. K., Seinfeld, J. H., Ng, N. L., Kroll, J. H., Fu, T.-M., Jacob, D. J., and Heald, C. L.: Global modeling of secondary organic aerosol formation from aromatic hydrocarbons: high- vs. low-yield pathways, Atmos. Chem. Phys., 8, 2405–2420, doi:10.5194/acp-8-2405-2008, 2008. Hodzic, A., Jimenez, J. L., Madronich, S., Canagaratna, M. R., DeCarlo, P. F., Kleinman, L., and Fast, J.: Potential contribution of semi-volatile and intermediate volatility primary organic compounds to secondary organic aerosol in the Mexico City region, Atmos. Chem. Phys. Discuss., 10, 657–710, doi:10.5194/acpd-10-657-2010, 2010. Huffman, J. A., Docherty, K. S., Aiken, A. C., Cubison, M. J., Ulbrich, I. M., DeCarlo, P. F., Sueper, D., Jayne, J. T., Worsnop, D. R., Ziemann, P. J., and Jimenez, J. L.: Chemically-resolved aerosol volatility measurements from two megacity field studies, Atmos. Chem. Phys., 9, 7161–7182, doi:10.5194/acp-9-7161-2009, 2009a. Huffman, J A., Docherty, K S., Mohr, C., Cubison, M J., Ulbrich, I M., Ziemann, P J., Onasch, T B., and Jimenez, J L.: Chemically-resolved volatility measurements of organic aerosol from different sources, Environ. Sci. Technol., 43, 5351–5357, \doi10.1021/ES803539d, 2009b. Jimenez, J L., Canagaratna, M R., Donahue, N M., Prevot, A. S H., Zhang, Q., Kroll, J H., DeCarlo, P F., Allan, J D., Coe, H., Ng, N L., Aiken, A C., Docherty, K S., Ulbrich, I M., Grieshop, A P., Robinson, A L., Duplissy, J., Smith, J D., Wilson, K R., Lanz, V A., Hueglin, C., Sun, Y L., Tian, J., Laaksonen, A., Raatikainen, T., Rautiainen, J., Vaattovaara, P., Ehn, M., Kulmala, M., Tomlinson, J M., Collins, D R., Cubison, M J., Dunlea, E J., Huffman, J A., Onasch, T B., Alfarra, M R., Williams, P I., Bower, K., Kondo, Y., Schneider, J., Drewnick, F., Borrmann, S., Weimer, S., Demerjian, K., Salcedo, D., Cottrell, L., Griffin, R., Takami, A., Miyoshi, T., Hatakeyama, S., Shimono, A., Sun, J Y., Zhang, Y M., Dzepina, K., Kimmel, J R., Sueper, D., Jayne, J T., Herndon, S C., Trimborn, A M., Williams, L R., Wood, E C., Middlebrook, A M., Kolb, C E., Baltensperger, U., and Worsnop, D R.: Evolution of organic aerosols in the atmosphere, Science, 326, 1525–1529, \doi10.1126/SCIENCE.1180353, 2009. Jordan, C E., Ziemann, P J., Griffin, R J., Lim, Y B., Atkinson, R., and Arey, J.: Modeling SOA formation from OH reactions with C-8-C-17 n-alkanes, Atmos. Environ., 42, 8015–8026, \doi10.1016/J.ATMOSENV.2008.06.017, 2008. Kaplan, I R. and Gordon, R J.: Non-fossil-fuel fine-particle organic-carbon aerosols in Southern California determined during the Los-Angeles aerosol characterization and source apportionment study, Aerosol. Sci. Tech., 21, 343–359, 1994. Kautzman, K E., Surratt, J., Chan, M N., Chan, A. W H., Hersey, S P., Chhabra, P S., Dalleska, N F., Wennberg, P O., Flagan, R C., and Seinfeld, J H.: Chemical composition of gas- and aerosol-phase products from the photooxidation of naphthalene, J. Phys. Chem. A, 114, 913–934, 2010. Kroll, J H., Smith, J D., Che, D L., Kessler, S H., Worsnop, D R., and Wilson, K R.: Measurement of fragmentation and functionalization pathways in the heterogeneous oxidation of oxidized organic aerosol, Phys. Chem. Chem. Phys., 11, 8005–8014, \doi10.1039/B905289e, 2009. Lane, T E., Donahue, N M., and Pandis, S N.: Simulating secondary organic aerosol formation using the volatility basis-set approach in a chemical transport model, Atmos. Environ., 42, 7439–7451, \doi10.1016/J.ATMOSENV.2008.06.026, 2008. Lelieveld, J., Butler, T M., Crowley, J N., Dillon, T J., Fischer, H., Ganzeveld, L., Harder, H., Lawrence, M G., Martinez, M., Taraborrelli, D., and Williams, J.: Atmospheric oxidation capacity sustained by a tropical forest, Nature, 452, 737–740, \doi10.1038/NATURE06870, 2008. Liao, H., Henze, D K., Seinfeld, J H., Wu, S L., and Mickley, L J.: Biogenic secondary organic aerosol over the United States: Comparison of climatological simulations with observations, J. Geophys. Res., 112, D06201, \doi10.1029/2006JD007813, 2007. Lipsky, E M. and Robinson, A L.: Effects of dilution on fine particle mass and partitioning of semivolatile organics in diesel exhaust and wood smoke, Environ. Sci. Technol., 40, 155–162, \doi10.1021/ES050319p, 2006. Marley, N. A., Gaffney, J. S., Tackett, M., Sturchio, N. C., Heraty, L., Martinez, N., Hardy, K. D., Marchany-Rivera, A., Guilderson, T., MacMillan, A., and Steelman, K.: The impact of biogenic carbon sources on aerosol absorption in Mexico City, Atmos. Chem. Phys., 9, 1537–1549, doi:10.5194/acp-9-1537-2009, 2009. Murphy, B N. and Pandis, S N.: Simulating the formation of semivolatile primary and secondary organic aerosol in a regional chemical transport model, Environ. Sci. Technol., 43, 4722–4728, \doi10.1021/ES803168a, 2009. Ng, N. L., Kroll, J. H., Chan, A. W. H., Chhabra, P. S., Flagan, R. C., and Seinfeld, J. H.: Secondary organic aerosol formation from m-xylene, toluene, and benzene, Atmos. Chem. Phys., 7, 3909–3922, doi:10.5194/acp-7-3909-2007, 2007. Ng, N. L., Canagaratna, M. R., Zhang, Q., Jimenez, J. L., Tian, J., Ulbrich, I. M., Kroll, J. H., Docherty, K. S., Chhabra, P. S., Bahreini, R., Murphy, S. M., Seinfeld, J. H., Hildebrandt, L., DeCarlo, P. F., Lanz, V. A., Prevot, A. S. H., Dinar, E., Rudich, Y., and Worsnop, D. R.: Organic aerosol components observed in worldwide datasets from aerosol mass spectrometry, Atmos. Chem. Phys. Discuss., 9, 27745–27789, doi:10.5194/acpd-9-27745-2009, 2009. Odum, J R., Hoffmann, T., Bowman, F., Collins, D., Flagan, R C., and Seinfeld, J H.: Gas/particle partitioning and secondary organic aerosol yields, Environ. Sci. Technol., 30, 2580–2585, 1996. Offenberg, J H., Kleindienst, T E., Jaoui, M., Lewandowski, M., and Edney, E O.: Thermal properties of secondary organic aerosols, Geophys. Res. Lett., 33, L03816, \doi10.1029/2005GL024623, 2006. Pankow, J F.: An absorption-model of gas-particle partitioning of organic-compounds in the atmosphere, Atmos. Environ., 28, 185–188, 1994. Park, R J., Jacob, D J., Chin, M., and Martin, R V.: Sources of carbonaceous aerosols over the United States and implications for natural visibility, J. Geophys. Res., 108(D12), 4355, \doi10.1029/2002JD003190, 2003. Park, R J., Jacob, D J., Field, B D., Yantosca, R M., and Chin, M.: Natural and transboundary pollution influences on sulfate-nitrate-ammonium aerosols in the United States: Implications for policy, J. Geophys. Res., 109, D15204, \doi10.1029/2003JD004473, 2004. Park, R J., Jacob, D J., Kumar, N., and Yantosca, R M.: Regional visibility statistics in the United States: Natural and transboundary pollution influences, and implications for the Regional Haze Rule, Atmos. Environ., 40, 5405–5423, \doi10.1016/J.ATMOSENV.2006.04.059, 2006. Presto, A A., Miracolo, M A., Kroll, J H., Worsnop, D R., Robinson, A L., and Donahue, N M.: Intermediate-volatility organic compounds: A potential source of ambient oxidized organic aerosol, Environ. Sci. Technol., 43, 4744–4749, \doi10.1021/ES803219q, 2009. Pye, H. O T., Liao, H., Wu, S., Mickley, L J., Jacob, D J., Henze, D K., and Seinfeld, J H.: Effect of changes in climate and emissions on future sulfate-nitrate-ammonium aerosol levels in the United States, J. Geophys. Res., 114, D01205, \doi10.1029/2008JD010701, 2009. Rind, D., Lerner, J., Jonas, J., and McLinden, C.: Effects of resolution and model physics on tracer transports in the NASA Goddard Institute for Space Studies general circulation models, J. Geophys. Res., 112, D09315, \doi10.1029/2006JD007476, 2007. Robinson, A L., Donahue, N M., Shrivastava, M K., Weitkamp, E A., Sage, A M., Grieshop, A P., Lane, T E., Pierce, J R., and Pandis, S N.: Rethinking organic aerosols: Semivolatile emissions and photochemical aging, Science, 315, 1259–1262, \doi10.1126/SCIENCE.1133061, 2007. Sander, R.: Compilation of Henry's Law constants for inorganic and organic species of potential importance in environmental chemistry (version 3), http://www.henrys-law.org, 1999. Schauer, J J., Kleeman, M J., Cass, G R., and Simoneit, B. R T.: Measurement of emissions from air pollution sources. 3. C-1-C-29 organic compounds from fireplace combustion of wood, Environ. Sci. Technol., 35, 1716–1728, \doi10.1021/ES001331e, 2001. Schauer, J J., Kleeman, M J., Cass, G R., and Simoneit, B. R T.: Measurement of emissions from air pollution sources. 5. C-1-C-32 organic compounds from gasoline-powered motor vehicles, Environ. Sci. Technol., 36, 1169–1180, \doi10.1021/ES0108077, 2002. Schichtel, B A., Malm, W C., Bench, G., Fallon, S., McDade, C E., Chow, J C., and Watson, J G.: Fossil and contemporary fine particulate carbon fractions at 12 rural and urban sites in the United States, J. Geophys. Res., 113, D02311, \doi10.1029/2007JD008605, 2008. Sheesley, R. J., KrusÃ¥, M., Krecl, P., Johansson, C., and Gustafsson, Ö.: Source apportionment of elevated wintertime PAHs by compound-specific radiocarbon analysis, Atmos. Chem. Phys., 9, 3347–3356, doi:10.5194/acp-9-3347-2009, , 2009. Shrivastava, M K., Lipsky, E M., Stanier, C O., and Robinson, A L.: Modeling semivolatile organic aerosol mass emissions from combustion systems, Environ. Sci. Technol., 40, 2671–2677, \doi10.1021/ES0522231, 2006. Shrivastava, M K., Lane, T E., Donahue, N M., Pandis, S N., and Robinson, A L.: Effects of gas particle partitioning and aging of primary emissions on urban and regional organic aerosol concentrations, J. Geophys. Res., 113, D18301, \doi10.1029/2007JD009735, 2008. Szidat, S.: Radiocarbon analysis of carbonaceous aerosols: Recent developments, Chimia, 63, 157–161, \doi10.2533/CHIMIA.2009.157, 2009. Turpin, B J. and Lim, H J.: Species contributions to \chemPM_2.5 mass concentrations: Revisiting common assumptions for estimating organic mass, Aerosol. Sci. Tech., 35, 602–610, 2001. van der Werf, G. R., Randerson, J. T., Giglio, L., Collatz, G. J., Kasibhatla, P. S., and Arellano Jr., A. F.: Interannual variability in global biomass burning emissions from 1997 to 2004, Atmos. Chem. Phys., 6, 3423–3441, doi:10.5194/acp-6-3423-2006, 2006. Weber, R. J., Sullivan, A. P., Peltier, R. E., Russell, A., Yan, B., Zheng, M., de Gouw, J., Warneke, C., Brock, C., Holloway, J. S., Atlas, E. L., and Edgerton, E.: A study of secondary organic aerosol formation in the anthropogenic-influenced southeastern United States, J. Geophys. Res., 112, D13302, \doi10.1029/2007JD008408, 2007. Wesely, M L.: Parameterization of surface resistances to gaseous dry deposition in regional-scale numerical-models, Atmos. Environ., 23, 1293–1304, 1989. Wu, S L., Mickley, L J., Jacob, D J., Logan, J A., Yantosca, R M., and Rind, D.: Why are there large differences between models in global budgets of tropospheric ozone?, J. Geophys. Res., 112, D05302, \doi10.1029/2006JD007801, 2007. Wu, S L., Mickley, L J., Leibensperger, E M., Jacob, D J., Rind, D., and Streets, D G.: Effects of 2000–2050 global change on ozone air quality in the United States, J. Geophys. Res., 113, D06302, \doi10.1029/2007JD008917, 2008. Zhang, L M., Gong, S L., Padro, J., and Barrie, L.: A size-segregated particle dry deposition scheme for an atmospheric aerosol module, Atmos. Environ., 35, 549–560, 2001. Zhang, Q., Worsnop, D. R., Canagaratna, M. R., and Jimenez, J. L.: Hydrocarbon-like and oxygenated organic aerosols in Pittsburgh: insights into sources and processes of organic aerosols, Atmos. Chem. Phys., 5, 3289–3311, doi:10.5194/acp-5-3289-2005, 2005. Zhang, Q., Jimenez, J L., Canagaratna, M R., Allan, J D., Coe, H., Ulbrich, I., Alfarra, M R., Takami, A., Middlebrook, A M., Sun, Y L., Dzepina, K., Dunlea, E., Docherty, K., DeCarlo, P F., Salcedo, D., Onasch, T., Jayne, J T., Miyoshi, T., Shimono, A., Hatakeyama, S., Takegawa, N., Kondo, Y., Schneider, J., Drewnick, F., Borrmann, S., Weimer, S., Demerjian, K., Williams, P., Bower, K., Bahreini, R., Cottrell, L., Griffin, R J., Rautiainen, J., Sun, J Y., Zhang, Y M., and Worsnop, D R.: Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically-influenced Northern Hemisphere midlatitudes, Geophys. Res. Lett., 34, L13801, \doi10.1029/2007GL029979, 2007. Zhang, Y X. and Tao, S.: Global atmospheric emission inventory of polycyclic aromatic hydrocarbons (PAHs) for 2004, Atmos. Environ., 43, 812–819, \doi10.1016/J.ATMOSENV.2008.10.050, 2009.