Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 6 12 2006 10.5194/acp-6-5573-2006 http://www.atmos-chem-phys.net/6/5573/2006/ http://www.atmos-chem-phys.net/6/5573/2006/acp-6-5573-2006.html http://www.atmos-chem-phys.net/6/5573/2006/acp-6-5573-2006.pdf 5573 5588 2006-12-13 The characterisation of pollution aerosol in a changing photochemical environment M. J. Cubison michael.cubison@colorado.edu M. R. Alfarra J. Allan K. N. Bower H. Coe G. B. McFiggans J. D. Whitehead P. I. Williams Q. Zhang J. L. Jimenez J. Hopkins J. Lee School of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, UK Dept. of Chemistry and Biochemistry and Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA Dept. of Chemistry, University of York, Heslington, York, UK now at: Cooperative Institute for Research in the Environmental Sciences, University of Colorado, Boulder, CO, USA now at: Laboratory for Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland Measurements are presented from a sampling location 50 km downwind of Greater London, UK, to investigate the timescales required for the atmospheric transformations of aerosol in urban emissions plumes in the context of photochemical age based on the benzene to toluene ratio. It is shown that particles at or around 100 nm in diameter exhibit the greatest systematic variability in chemical properties, and thus hygroscopic properties, on a timescale of 1–2 days. The smaller Aitken mode and larger accumulation mode particles exhibit less variability on these timescales, which we propose is as a result of their different residence times in the atmosphere. The larger accumulation particles have been in the atmosphere longer than the 100 nm particles and their chemistry and hygroscopic properties have been integrated over several days and potentially over several source regions. In contrast, the smaller Aitken mode particles show little systematic variability with photochemical age because their atmospheric lifetimes are short, thus chemical changes and hence changes in water affinity have not had time to occur. Increases in the particle diameter of up to 40% are observed at 90% relative humidity in the accumulation mode from the uptake of water as the particles become increasingly soluble in nature. Alfarra, M., Coe, H., Allan, J., Bower, K., Boudries, H., Canagaratna, M., Jimenez, J., Jayne, J., Garforth, A., Li, S.-M., and Worsnop, D.: Characterization of urban and rural organic particulate in the Lower Fraser Valley using two Aerodyne Aerosol Mass Spectrometers, Atmos. Environ., 38, 5745–5758, 2004. Allan, J. D., Jimenez, J. L., Williams, P. I., Alfarra, M. R., Bower, K. N., Jayne, J. T., Coe, H., and Worsnop, D. R.: Quantitative sampling using an Aerodyne aerosol mass spectrometer 1. Techniques of data interpretation and error analysis, J. Geophys. Res., 108(D3), 4090, doi:10.1029/2002JD002358, 2003a. Allan, J. D., Alfarra, M., Bower, K., Williams, P., Gallagher, M., Jimenez, J., McDonald, A., Nemitz, E., Canagaratna, M., Jayne, J., Coe, H., and Worsnop, D.: Quantitative sampling using an Aerodyne aerosol mass spectrometer 2. Measurements of fine particulate chemical composition in two U.K. cities, J. Geophys. Res., 108(D3), 4091, doi:10.1029/2002JD002359, 2003b. Allan, J., Delia, A., Coe, H., Bower, K., Alfarra, M., Jimenez, J., Middlebrook, A., Jayne, J., and Worsnop, D.: A generalised method for the extraction of chemically resolved mass spectra from Aerodyne aerosol mass spectrometer data, J. Aerosol Sci., 35, 909–922, 2004b. Alonso, M., Alguacil, F., Martin, M., Kousaka, Y., and Nomura, T.: Aerosol particle size growth by simultaneous coagulation and condensatioon with diffusion losses in laminar flow tubes, J. Aerosol Sci., 30, 1191–1199, 1999. Atkinson, R.: Gas-phase tropospheric chemistry of organic compounds, J. Phys. Chem. Ref. Data, Monograph 2, 1–216, 1994. Barrett, J. and Baldwin, T.: Aerosol nucleation and growth during laminar tube flow – maximum saturations and nucleation rates, J. Aerosol Sci., 31, 633–650, 2000. Barrett, J. and Baldwin, T.: Aerosol nucleation and growth during laminar tube flow – quenching effects and wall condensation, J. Aerosol Sci., 32, 957–974, 2001. Barrett, J. and Clement, C.: Growth rates for liquid drops, J. Aerosol Sci., 19, 223–242, 1988. Berg, O., Swietlicki, E., and Krejci, R.: Hygroscopic growth of aerosol particles in the marine boundary layer over the Pacific and Southern Oceans during the First Aerosol Characterization Experiment (ACE 1), J. Geophys. Res., 103D, 16 535–16 546, 1998. Calvert, J.: Hydrocarbon involvement in photochemical smog formation in Los Angeles atmosphere, Environ. Sci. Technol., 10, 256–262, 1976. Claeys, M., Graham, B., Vas, G., Wang, W., Vermeylen, R., Pashynska, V., Cafmeyer, J., Guyon, P., Andreae, M., Artaxo, P., and Maenhaut, W.: Formation of secondary organic aerosols through photo-oxidation of isoprene, Science, 303, 1173–1176, 2004. Cocker, D., Whitlock, N., Flagan, R., and Seinfeld, J.: Hygroscopic properties of Pasadena, California aerosol, Aerosol Sci. Technol., 35, 637–647, 2001. Cooke, W. F., Ramaswamy, V., and Kasibhatla, P.: A general circulation model study of the global carbonaceous aerosol distribution, J. Geophys. Res., 107(D16), 4279, doi:10.1029/2001JD001274, 2002. Covert, D. and Heintzenberg, J.: Size distributions and chemical properties of aerosol at Ny-Alesund, Svalbard, Atmos. Environ., 27A, 2989–2997, 1993. Cubison, M., Gysel, M., and Coe, H.: A modified hygroscopic tandem DMA and a data retrieval method based on optimal estimation, J. Aerosol Sci., 36, 846–865, 2005. DeCarlo, P., Slowik, J. G., Worsnop, D. R., Davidovits, P., and Jimenez, J. L.: Particle Morphology and Density Characterization by Combined Mobility and Aerodynamic Diameter Measurements. Part 1: Theory, Aerosol Sci. Technol., 38, 1185–1205, 2004, doi:10.1080/027868290903907. Donaldson, K., Li, X., and MacNee, W.: Ultrafine (nanometre) particle mediated lung injury, J. Aerosol Sci., 29, 553–560, 1998. Drewnick, F., Schwab, J., Jayne, J., Canagaratna, M., Worsnop, D., and Demerjian, K.: Measurement of Ambient Aerosol Composition During the PMTACS-NY 2001 Using an Aerosol Mass Spectrometer. Part I: Mass Concentrations, Aerosol Sci. Technol., 38(S1), 92–103, 2004. Dusek, U., Frank, G. P., Hildebrandt,L., Curtius, J., Schneider, J., Walter, S., Chand, D., Drewnick, F., Hings, S., Jung, D., Borrmann, S. and Andreae, M.O.: Size matters more than chemistry for cloud-nucleating ability of aerosol particles, Science, 312(5778), 1375–1378, 2006. Ghio, A. and Devlin, R.: Inflammatory lung injury after bronchial instillation of air pollution particles, Am. J. Resp. Crit. Care, 164(4), 704–708, 2001. Heard, D. E., Carpenter, L. J., Creasey, D. J., Hopkins, J. R., Lee, J. D., Lewis, A. C., Pilling, M. J., Seakins, P. W., Carslaw, N., and Emmerson, K. M.: High levels of the hydroxyl radical in the winter urban troposphere, Geophys. Res. Lett., 31, L18112, doi:10.1029/2004GL020544, 2004. Hopkins, J., Lewis, A., and Reid, K.: A two-column method for long-term monitoring of nonmethane hydrocarbons (NMHCs) and oxygenated volatile organic compounds (o-VOCs), J. Environ. Monitor., 5, 8–13, 2003. Horak Jr., F., Frischer, T., Studnicka, M., Gartner, C., Hauck, H., and Preining, O.: The chemical composition of particulate matter has a short term effect on the lung function of pre-school children, Eur. Respri. J., 18, Suppl 33, 128, 2001. IPCC: Climate change 2001: Scientific basis. Third assessment of the Inter-govermental Panel on Climate Change, Cambridge, 2001. Jacobson, M. Z.: Fundamentals of Atmospheric Modelling, Cambridge University Press, Cambridge, UK, 1999. Jayne, J., Leard, D., Zhang, X., Davidovits, P., Smith, K., Kolb, C., and Worsnop, D.: Development of an aerosol mass spectrometer for size and composition analysis of submicron particles, Aerosol Sci. Technol., 33, 49–70, 2000. Jimenez, J. L., Bahreini, R., Cocker III, D. R., Zhuang, H., Varutbangkul, V., Flagan, R. C., Seinfeld, J. H., O'Dowd, C. D., and Hoffmann, T.: New particle formation from photooxidation of diiodomethane (CH2I2), J. Geophys. Res., 108(D10), 4318, doi:10.1029/2002JD002452, 2003. Kim, C. and Jaques, P.: Respiratory dose of inhaled ultrafine particles in healthy adults, Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng. Sci., 358, 2693–2705, 2000. Kittelson, D.: Engines and nanoparticles: A review, J. Aerosol Sci., 29, 575–588, 1998. Kleinmann, L., Daum, P., Lee, Y.-N., Nunnermacker, L., Springston, S., Weinstein-Lloyd, J., Hyde, P., Doskey, P., Rudolph, J., Fast, J., and Berkowitz, C.: Photochemical age determinations in the Phoenix metropolitan area, J. Geophys. Res., 108(D3), 4096, doi:10.1029/2002JD002621, 2003. Koch, D.: Transport and direct radiative forcing of carbonaceous and sulphate aerosols in the GISS GCM, J. Geophys. Res., 106D, 311–322, 2001. Kulmala, M.: How particles nucleate and grow, Science, 302, 1000–1001, 2003. Kulmala, M., Majerowicz, A., and Wagner, P.: Condensational growth at large vapour concentration: Limits of applicability of the Mason equation, J. Aerosol Sci., 20, 1023–1026, 1989. Kulmala, M., Laakso, L., Lehtinen, K., Riipinen, I., Del Maso, M., Anttila, T., Kerminen, V.-M., Horrak, U., Vana, M., and Tammet, H.: Initial steps of aerosol growth, Atmos. Chem. Phys., 4, 2553–2560, 2004a. Lee, A., Bartle, K., and Lewis, A.: A Model of Peak Amplitude Enhancement in Orthogonal Two-Dimensional Gas Chromatography., Analytical Chem., 73, 1324–1329, 2001. Lee, K.: Change of particle size distribution during Brownian coagulation, J. Colloid Interf. Sci., 92, 315–325, 1983. Lewis, A., Bartle, K., McQuaid, J., Pilling, M., Seakins, P., and Ridgeon, P.: Atmospheric monitoring of volatile organic compounds using programmed temperature vaporisation injection, J. High Res. Chromatog., 19, 686–690, 1996. Lewis, A., Carslaw, N., Marriott, P., Kinghorn, R., Morrison, P., Lee, A., Bartle, K., and Pilling, M.: A larger pool of ozone-forming carbon compounds in urban atmospheres, Nature, 405, 778–781, 2000. Limbeck, A., Kulmala, M., and Puxbaum, H.: Secondary organic aerosol formation in the atmosphere via heterogeneous reaction of gaseous isoprene on acidic particles, Geophys. Res. Lett., 30(19), 1996, doi:10.1029/2003GL017738, 2003. Lohmann, U., Feichter, J., Penner, J., and Leaitch, R.: Indirect effect of sulphate and carbonaceous aerosols: a mechanistic treatment, J. Geophys. Res., 105D, 193–206, 2000. Luria, M. and Sievering, H.: Heterogeneous and homogeneous oxidation of SO2 in the remote marine atmosphere, Atmos. Environ., 25A, 1489–1496, 1991. Malet, J., Alloul, L., Michielsen, N., Bouland, D., and Renoux, A.: Deposition of nanosized particles in cylindrical tubes under laminar and turbulent flow conditions, J. Aerosol Sci., 31, 335–348, 2000. Maßling, A., Wiedensohler, A., and Voutilainen, A.: Hygroscopic properties of submicrometer aerosol particles during ACE-Asia, in: Abstracts of the European Aerosol Conference 2003, vol 1, pp S9–S10, 2003. McFiggans, G., Alfarra, M., Allan, J., Bower, K., Coe, H., Cubison, M., Topping, D., Williams, P., Decesari, S., Facchini, C., and Fuzzi, S.: Simplification of the representation of the organic component of atmospheric particulates, Faraday Discuss., 130, 341, doi:10.1039/b419435g, 2005. McFiggans, G., Artaxo, P., Baltensperger, U., Coe, H., Facchini, M.-C., Feingold, G., Fuzzi, S., Gysel, M., Laaksonen, A., Lohmann, U., Mentel, T., Murphy, D., O'Dowd, C., Snider, J., and Weingartner, E.: The effect of physical and chemical aerosol properties on warm cloud droplet activation, Atmos. Chem. Phys., 6, 2593–2649, 2006. McKeen, S. and Liu, S.: Hydrocarbon ratios and photochemical history of air masses, Geophys. Res. Lett., 20, 2363–2366, 1993. McKeen, S., Liu, S., Hsie, E.-Y., Lin, X., Bradshaw, J., Smyth, S., Gregory, G., and Blake, D.: Hydrocarbon ratios during PEM West A: a model perspective, J. Geophys. Res., 101D, 2087–2109, 1996. McMurry, P., Litchy, M., Huang, P.-F., Cai, X., Turpin, B., Dick, W., and Hanson, A.: Elemental composition and morphology of individual particles separated by size and hygroscopicity with the TDMA, Atmos. Environ., 30, 101–108, 1996. McMurry, P. H. and Stolzenburg, M. R.: On the sensitivity of particle size to relative humidity for Los Angeles Aerosols, Atmos. Environ., 23, 497–507, 1989. Molina, M. J., Ivanov, A. V., Trakhtenberg, S., and Molina, L. T.: Atmospheric evolution of organic aerosol, Geophys. Res. Lett., 31, L22104, doi:10.1029/2004GL020910, 2004. Moshammer, H. and Neuberger, M.: The active surface of suspended particles as a predictor of lung function and pulmonary symptoms in Austrian school children, Atmos. Environ., 37, 1737–1744, 2003. Neuberger, M., Moshammer, H., and Kundi, M.: Declining ambient air pollution and lung function improvement in Austrian children, Atmos Environ, 36, 1733–1736, 2002. Neuberger, M., Schimek, M., Horak Jnr, F., Moshammer, H., Kundi, M., Frischer, T., Gomiscek, B., Puxbaum, H., Hauck, H., and AUPHEP-Team.: Acute effects of particulate matter on respiratory diseases, symptoms and functions: epidemiological results of the Austrian Project on Health Effects of Particulate Matter (AUPHEP), Atmos. Environ., 38, 3971–3981, 2004. O'Dowd, C., Facchini, M., Cavalli, F., Ceburnis, D., Mircea, M., Decesari, S., Fuzzi, S., Yoon, Y., and Putaud, J.-P.: Biogenically driven organic contribution to marine aerosol, Nature, 431, 676–680, 2004. Park, S. and Lee, K.: Condensational growth of polydisperse aerosol for the entire particle size range, Aerosol Sci. Technol., 33, 222–227, 2000. Park, S., Lee, K., Shimada, M., and Okuyama, K.: Alternative analytical solution to condensational growth of polydisperse aerosols in the continuum regime, J. Aerosol Sci., 32, 187–197, 2001. Parrish, D., Hahn, C., Williams, E., Norton, E., Fehsenfeld, F., Singh, H., Shetter, J., Gandrud, B., and Ridley, B.: Indications of photochemical histories of Pacific air masses from measurements of atmospheric trace species at Point Arena, California, J. Geophys. Res., 103D, 339–359, 1992. Penttinen, P., Timonen, K., Tiittanen, P., Mirme, A., Ruuskanen, J., and Pekkanen, J.: Ultrafine particles in urban air and respiratory health among adult asthmatics, Eur. Respir. J., 17, 428–435, 2001. Pich, J., Friedlander, S., and Laj, F.: The self-preserving particle size distribution for coagulation by Brownian motion. III. Smoluchowski coagulation and simultaneous Maxwellian condensation, J. Aerosol Sci., 1, 115–126, 1970. Pope, C., Schwartz, J., and Ransom, M.: Daily mortality and PM10 pollution in Utah valley, Arch. Environ. Health, 47, 211–217, 1992. Pope III, C.: Review: epidemiological basis for particulate air pollution health standards, Aerosol Sci. Tech., 32, 4–14, 2000. Putaud, J.-P., Raes, F., Van-Dingenen, R., Brüggemann, E., Facchini, M.-C., Decesari, S., Fuzzi, S., Gehrig, R., Hüglin, C., Laj, P., Lorbeer, G., Maenhaut, W., Mihalopoulos, N., Müller, K., Querol, X., Rodriguez, S., Schneider, J., Spindler, G., ten Brink, H., Torseth, K., and Wiedensohler, A.: A European aerosol phenomenology. 2: chemical characteristics of particulate matter at kerbside, urban, rural and background sites in Europe, Atmos. Environ., 38, 2579–2595, 2004. Rader, D. and McMurry, P.: Application of the tandem differential mobility analyser for studies of droplet growth or evaporation, J. Aerosol. Sci., 17, 771–787, 1986. Raymond, T. M. and Pandis, S. N.: Formation of cloud droplets by multicomponent organic particles, J. Geophys. Res., 108(D15), 4469, doi:10.1029/2003JD003503, 2003. Reddy, M. S. and Boucher, O.: A study of the global cycle of carbonaceous aerosols in the LMDZT general circulation model, J. Geophys. Res., 109(D14), 202, doi:10.1029/2003JD004048, 2004. Riemer, N., Vogel, H., and Vogel, B.: Soot aging time scales in polluted regions during day and night, Atmos. Chem. Phys., 4, 1885–1893, 2004. Roberts, J., Fehsenfeld, F., Liu, S., Bollinger, M., Hahn, C., Albritton, D., and Sievers, R.: Measurements of aromatic hydrocarbon ratios and NOx concentrations in the rural troposphere: observation of air mass photochemical aging and NO_x removal, Atmos. Environ., 18, 2421–2432, 1984. Rudolph, J. and Czuba, E.: On the use of isotopic composition measurements of volatile organic compounds to determine the photochemical age of an air mass, Geophys. Res. Lett., 27, 3865–3868, 2000. Rudolph, J. and Johnen, F.: Measurments of light hydrocarbons over the Atlantic in regions of low biological activity, J. Geophys. Res., 95D, 583–591, 1990. Schwartz, J., Dockery, D., and Neas, L.: Is daily mortality associated with fine particles?, J. Air Waste Manage., 46, 927–939, 1996. Svenningsson, I. B., Hansson, H. C., Wiedensohler, A., Ogren, J. A., Noone, K. J., and Hallberg, A.: Hygroscopic growth of aerosol particles in the Po Valley, Tellus, 44B, 556–569, 1992. Svenningsson, I. B., Hansson, H. C., Wiedensohler, A., Ogren, J. A., Noone, K. J., Hallberg, A., and Colvile, R.: Hygroscopic growth of aerosol particles and its influence on nucleation scavenging in Cloud – experimental results from Kleiner-Feldberg, J. Atmos. Chem., 19(1–2), 129–152, 1994. Swietlicki, E., Zhou, J., Berg, O., Nilsson, E., Aalto, P., and Leck, C.: Hygroscopic behaviour of aerosol particles in the Arctic marine boundary layer – Relation to air mass history and mixing, J. Aerosol Sci., 29(S1), S9–S10, 1998. Swietlicki, E., Zhou, J., Berg, O., Martinsson, B., Frank, G., Cederfelt, S., Dusek, U., Berner, A., Birmili, W., Wiedensohler, A., Yuskiewicz, B., and Bower, K.: A closure study of sub-micrometer aerosol particle hygroscopic behaviour, Atmos. Res., 50, 205–240, 1999. Swietlicki, E., Zhou, J., Covert, D., Hämeri, K., Busch, B., Väkevä, M., Dusek, U., Berg, O., Wiedensohler, A., Aalto, P., Mäkelä, J., Martinsson, B., Papaspiropoulos, G., Mentes, B., Frank, G., and Stratmann, F.: Hygroscopic properties of aerosol particles in the north-eastern Atlantic during ACE-2, Tellus, 52B, 201–227, 2000. Sydbom, A., Blomberg, A., Parnia, S., Stenfors, N., Sandstrom, T., and Dahlen, S. E.: Health effects of diesel exhaust emissions, Eur. Resp. J., 17, 773–746, 2001. Topping, D., McFiggans, G., and Coe, H.: A curved multi-component aerosol hygroscopicity model framework: Part – Inorganic compounds, Atmos. Chem. Phys., 5, 1205–1222, 2005a. Topping, D., Coe, H., McFiggans, G., Burgess, R., Allan, J., Alfarra, M., Bower, K., Choularton, T., Decesari, S., and Facchini, M.-C.: A curved multi-component aerosol hygroscopicity model framework: Part 2 – Including organic compounds, Atmos. Chem. Phys., 5, 1223–1242, 2005b. Trakumas, S., Juozaitis, A., Buzorius, G., Girg\vzdys, A., and Ulevièius, V.: Investigations of hygroscopical properties of atmospheric aerosol particles, J. Aerosol Sci., 26, S371–S372, 1995. Väkevä, M., Kulmala, M., Stratmann, F., and Hämeri, K.: Field measurements of hygroscopic properties and state of mixing of nucleation mode particles, Atmos. Chem. Phys., 2, 55–66, 2002. van Dingenen, R., Raes, F., Putaud, J.-P., Baltensperger, U., Charron, A., Facchini, M.-C., Decesari, S., Fuzzi, S., Gehrig, R., Hansson, H.-C., Harrison, R., Hüglin, C., Jones, A., Laj, P., Lorbeer, G., Maenhaut, W., Palmgren, F., Querol, X., Rodriguez, S., Schneider, J., tenBrink, H., Tunved, P., Torseth, K., Wehner, B., Weingartner, E., Wiedensohler, A., and Wahlin, P.: A European aerosol phenomenology. 1: Physical characteristics of particulate matter at kerbside, urban, rural and background sites in Europe, Atmos. Environ., 38, 2561–2577, 2004. Volkamer, R., Jimenez, J. L., San Martini, F., Dzepina, K., Zhang, Q., Salcedo, D., Molina, L. T., Worsnop, D. R., and Molina, M. J.: Secondary Organic Aerosol Formation from Anthropogenic Air Pollution: Rapid and Higher than Expected, Geophys. Res. Lett., 33(17), L17811, doi:10.1029/2006GL026899, 2006. Weingartner, E., Baltensperger, U., and Burtscher, H.: Growth and structural change of combustion aerosols at high relative humidity, Environ. Sci. Technol., 29, 2982–2986, 1995. Weingartner, E., Burtscher, H., and Baltensperger, U.: Hygroscopic properties of carbon and diesel soot particles, Atmos. Environ., 31, 2311–2327, 1997. Williams, M.: Growth rates of liquid drops for large saturation ratios, J. Aerosol Sci., 26, 477–487, 1995. Williams, P., Gallagher, M., Choularton, T., Coe, H., Bower, K., and McFiggans, G.: Aerosol development and interaction in an urban plume, Aerosol Sci. and Technol., 32, 120–126, 2000. Wilson, R. and Spengler, J.: Particles in our air, Harvard Univeristy Press, USA, 1996. Zhang, Q., Alfarra, M., Worsnop, D., Allan, J., Coe, H., Canagaratna, M., and Jimenez, J.: Deconvolution and Quantification of Hydrocarbon-Like and Oxygenated Organic Aerosols Based on Aerosol Mass Spectrometry, Environ. Sci. Technol., 39, 4938–4952, 2005a. Zhang, Q., Canagaratna, M. R., Jayne, J. T., Worsnop, D. R., and Jimenez, J.-L.: Time- and size-resolved chemical composition of submicron particles in Pittsburgh: Implications for aerosol sources and processes, J. Geophys. Res., 110, D07S09, doi:10.1029/2004JD004649, 2005b. 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, 2005c. Zhang, X., McMurry, P., Hering, S., and Casuccio, G.: Mixing characteristics and water content of submicron aerosols measured in Los Angeles and at the Grand Canyon, Atmos. Environ., 27A, 1593–1607, 1993. Zhou, J., Swietlicki, E., Hansson, H. C., and Artaxo, P.: Submicrometer aerosol particle size distribution and hygroscopic growth measured in the Amazon rain forest during the wet season, J. Geophys. Res., 107(D20), 8055, doi:10.1029/2000JD000203, 2002. Zimmer, A.: The influence of metallurgy on the formation of welding aerosols, J. Environ. Monitor., 4, 628–632, 2002.