<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE article SYSTEM "http://www.atmos-chem-phys-discuss.net/inc/acpd/copernicus.dtd">
<article language="en">
	<journal>
		<journal_title>Atmospheric Chemistry and Physics Discussions</journal_title>
		<journal_url>www.atmos-chem-phys-discuss.net</journal_url>
		<issn>1680-7367</issn>
		<eissn>1680-7375</eissn>
		<volume_number>7</volume_number>
		<issue_number>3</issue_number>
		<publication_year>2007</publication_year>
	</journal>
	<doi>10.5194/acpd-7-6413-2007</doi>
	<article_url>http://www.atmos-chem-phys-discuss.net/7/6413/2007/</article_url>
	<abstract_html>http://www.atmos-chem-phys-discuss.net/7/6413/2007/acpd-7-6413-2007.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys-discuss.net/7/6413/2007/acpd-7-6413-2007.pdf</fulltext_pdf>
	<start_page>6413</start_page>
	<end_page>6457</end_page>
	<publication_date>2007-05-11</publication_date>
	<article_title content_type="html">Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>R. C. Moffet</name>
		</author>
		<author numeration="2" affiliations="2,3">
			<name>B. de Foy</name>
		</author>
		<author numeration="3" affiliations="2,4">
			<name>L. T. Molina</name>
		</author>
		<author numeration="4" affiliations="1">
			<name>M. J. Molina</name>
		</author>
		<author numeration="5" affiliations="1">
			<name>A. Prather</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">University of California, San Diego, La Jolla, CA, USA</affiliation>
		<affiliation numeration="2" content_type="html">Molina Center for Energy and the Environment (MCE&lt;sup&gt;2&lt;/sup&gt;), La Jolla,d CA, USA</affiliation>
		<affiliation numeration="3" content_type="html">Saint Louis University, Saint Louis, Missouri, USA</affiliation>
		<affiliation numeration="4" content_type="html">Massachusetts Institute of Technology, Cambridge, MA, USA</affiliation>
	</affiliations>
	<abstract content_type="html">Continuous ambient measurements with aerosol time-of-flight mass
spectrometry (ATOFMS) were carried out in an industrial/residential section
in the northern part of Mexico City as part of the Mexico City Metropolitan
Area &amp;ndash; 2006 campaign (MCMA-2006) between 7&amp;ndash;27 March, 2006. Biomass and
organic carbon (OC) particle types were found to dominate the accumulation
mode both day and night. The concentrations of both organic carbon and
biomass particles were roughly equal early in the morning, but biomass
became the largest contributor to the accumulation mode mass from the late
morning until early evening. The diurnal pattern can be attributed to aging
and/or a change in meteorology. Fresh elemental carbon (EC) particles were
observed during rush hour. The majority of the EC particles were mixed with nitrate, sulfate, organic carbon and potassium.
Submicron particles from industrial sources in the northeast were composed of an internal mixture of Pb, Zn, EC and Cl and
peaked early in the morning. A unique nitrogen-containing organic (NOC)
particle type was observed, and is hypothesized to be from industrial
emissions based on the temporal profile and back trajectory analysis. This
study provides unique insights into the real-time changes in single particle
mixing state as a function of size and time for aerosols in Mexico City.
These new findings indicate that biomass burning and industrial operations
make significant contributions to particles in Mexico City. These sources
have received relatively little attention in previous intensive field
campaigns.</abstract>
	<references>
		<reference numeration="1" content_type="text"> Aldape, F., Flores, J., Diaz, R. V., and Crumpton, D.: Upgrading of the PIXE system at ININ (Mexico) and report on elemental composition of atmospheric aerosols from 1990 in the ZMCM, Nucl. Instrum. Methods Phys. Res., Sect B, 109, 459&amp;ndash;464, 1996a. </reference>
		<reference numeration="2" content_type="text"> Aldape, F., Flores, J. , Garcia, R., and Nelson, J. W.: PIXE analysis of atmospheric aerosols from a simultaneous three site sampling during the autumn of 1993 in Mexico City, Nucl. Instrum. Methods Phys. Res., Sect B, 109, 502&amp;ndash;505, 1996b. </reference>
		<reference numeration="3" content_type="text"> Angelino, S., Suess, D. T., and Prather, K. A.: Formation of aerosol particles from reactions of secondary and tertiary alkylamines: Characterization by aerosol time-of-flight mass spectrometry, Environ. Sci. Technol., 35(15), 3130&amp;ndash;3138, 2001. </reference>
		<reference numeration="4" content_type="text"> Bassett, M. E. and Seinfeld, J. H.: Atmospheric equilibrium-model of sulfate and nitrate aerosols 2: Particle-size analysis, Atmos. Environ., 18(6), 1163&amp;ndash;1170, 1984. </reference>
		<reference numeration="5" content_type="text"> Baumgardner, D., Raga, G. B., and Muhlia, A.: Evidence for the formation of CCN by photochemical processes in Mexico City, Atmos. Environ., 38(3), 357&amp;ndash;367, 2004. </reference>
		<reference numeration="6" content_type="text"> Beddows, D. C. S., Donovan, R. J. , Harrison, R. M. , Heal, M. R., Kinnersley, R. P., King, M. D., Nicholson, D. H., and Thompson, K. C.: Correlations in the chemical composition of rural background atmospheric aerosol in the UK determined in real time using time-of-flight mass spectrometry, J. Environ. Monitor., 6(2), 124&amp;ndash;133, 2004. </reference>
		<reference numeration="7" content_type="text"> Blando, J. D. and Turpin, B. J.: Secondary organic aerosol formation in cloud and fog droplets: a literature evaluation of plausibility, Atmos. Environ., 34(10), 1623&amp;ndash;1632, 2000. </reference>
		<reference numeration="8" content_type="text"> Cahill, T. A., Morales, R., and Miranda, J.: Comparative aerosol studies of Pacific Rim cities &amp;ndash; Santiago, Chile (1987); Mexico City, Mexico (1987&amp;ndash;1990); and Los Angeles, USA (1973 and 1987), Atmos. Environ., 30(5), 747&amp;ndash;749, 1996. </reference>
		<reference numeration="9" content_type="text"> Chebbi, A. and Carlier, P.: Carboxylic acids in the troposphere, occurrence, sources, and sinks: A review, Atmos. Environ., 30(24), 4233&amp;ndash;4249, 1996. </reference>
		<reference numeration="10" content_type="text"> Chow, J. C., Watson, J. G., Edgerton, S. A., and Vega, E.: Chemical composition of PM2.5 and PM10 in Mexico City during winter 1997, Sci. Total Environ., 287(3), 177&amp;ndash;201, 2002a. </reference>
		<reference numeration="11" content_type="text"> Chow, J. C., Watson, J. G., Edgerton, S. A., Vega, E., and Ortiz, E.: Spatial differences in outdoor PM10 mass and aerosol composition in Mexico City, Journal of the Air and Waste Management Association, 52(4), 423&amp;ndash;434, 2002b. </reference>
		<reference numeration="12" content_type="text"> de Foy, B., Caetano, E., Magana, V., Zitacuaro, A., Cardenas, B., Retama, A., Ramos, R., Molina, L. T., and Molina, M. J.: Mexico City basin wind circulation during the MCMA-2003 field campaign, Atmos. Chem. Phys., 5, 2267&amp;ndash;2288, 2005. </reference>
		<reference numeration="13" content_type="text"> de Foy, B., Clappier, A., Molina, L. T., and Molina, M. J.: Distinct wind convergence patterns in the Mexico City basin due to the interaction of the gap winds with the synoptic flow, Atmos. Chem. Phys., 6, 1249&amp;ndash;1265, 2006a. </reference>
		<reference numeration="14" content_type="text"> de Foy, B., Lei, W., Zavala, M., Volkamer, R., Samuelsson, J., Mellqvist, J., Galle, B., Martinez, A. P., Grutter, M., and Molina, L. T.: Modelling Constraints on the emission inventory and on vertical diffusion for CO and SO2 in the Mexico City Metropolitan Area using Solar FITR and zenith sky UV spectroscopy, Atmos. Chem. Phys. Discuss., 6, 6125&amp;ndash;-6181, 2006b. </reference>
		<reference numeration="15" content_type="text"> de Foy, B. and Molina, L. T.: MODIS Land Surface Parameters for Improved MM5 Simulations in the Mexico City basin during the MILAGRO Field Campaign, in 7th Annual WRF User&apos;s Workshop, Boulder, Colorado, 2006. </reference>
		<reference numeration="16" content_type="text"> de Foy, B., Varela, J. R., Molina, L. T., and Molina, M. J.: Rapid ventilation of the Mexico City basin and regional fate of the urban plume, Atmos. Chem. Phys., 6, 2321&amp;ndash;2335, 2006c. </reference>
		<reference numeration="17" content_type="text"> Dunn, M. J., Jimenez, J. L., Baumgardner, D., Castro, T., McMurry, P. H., and Smith, J. N.: Measurements of Mexico City nanoparticle size distributions: Observations of new particle formation and growth, Geophys. Res. Lett., 31(10), L10102, doi:10.1029/2004GL019483, 2004. </reference>
		<reference numeration="18" content_type="text"> Ervens, B., Feingold, G., Frost, G. J., and Kreidenweis, S. M.: A modeling study of aqueous production of dicarboxylic acids: 1. Chemical pathways and speciated organic mass production, J. Geophys. Res. Atmos., 109(D15), D15205, doi:10.1029/2003JD004387, 2004. </reference>
		<reference numeration="19" content_type="text"> Falkovich, A. H., Graber, E. R., Schkolnik, G., Rudich, Y., Maenhaut, W., and Artaxo, P.: Low molecular weight organic acids in aerosol particles from Rondonia, Brazil, during the biomass-burning, transition and wet periods, Atmos. Chem. Phys., 5, 781&amp;ndash;797, 2005. </reference>
		<reference numeration="20" content_type="text"> Faust, B. C.: Photochemistry of Clouds, Fogs, and Aerosols, Environ. Sci. Technol., 28(5), A217&amp;ndash;A222, 1994. </reference>
		<reference numeration="21" content_type="text"> Flores, J., Aldape, F., Diaz, R. V., Hernandez-Mendez, B., and Garcia, R.: PIXE analysis of airborne particulate matter from Xalostoc, Mexico: winter to summer comparison, Nucl. Instrum. Methods Phys. Res., Sect B, 150(1&amp;ndash;4), 445&amp;ndash;449, 1999. </reference>
		<reference numeration="22" content_type="text"> Gard, E., Mayer, J. E., Morrical, B. D., Dienes, T., Fergenson, D. P., and Prather, K. A.: Real-time analysis of individual atmospheric aerosol particles: Design and performance of a portable ATOFMS, Anal. Chem. , 69(20), 4083&amp;ndash;4091, 1997. </reference>
		<reference numeration="23" content_type="text"> Gross, D. S., Galli, M. E., Kalberer, M., Prevot, A. S. H., Dommen, J., Alfarra, M. R., Duplissy, J., Gaeggeler, K., Gascho, A., Metzger, A., and Baltensperger, U.: Real-time measurement of oligomeric species in secondary organic aerosol with the aerosol time-of-flight mass spectrometer, Anal. Chem., 78(7), 2130&amp;ndash;2137, 2006. </reference>
		<reference numeration="24" content_type="text"> Gross, D. S., Galli, M. E., Silva, P. J., Wood, S. H., Liu, D. Y., and Prather, K. A.: Single particle characterization of automobile and diesel truck emissions in the Caldecott Tunnel, Aerosol Sci. Technol., 32(2), 152&amp;ndash;163, 2000. </reference>
		<reference numeration="25" content_type="text"> Guazzotti, S. A., Coffee, K. R., and Prather, K. A.: Continuous measurements of size-resolved particle chemistry during INDOEX-Intensive Field Phase 99, J. Geophys. Res. Atmos., 106(D22), 28 607&amp;ndash;28 627, 2001. </reference>
		<reference numeration="26" content_type="text"> Guazzotti, S. A., Suess, D. T., Coffee, K. R., Quinn, P. K. , Bates, T. S. , Wisthaler, A., Hansel, A., Ball, W. P., Dickerson, R. R., Neususs, C., Crutzen, P. J., and Prather, K. A.: Characterization of carbonaceous aerosols outflow from India and Arabia: Biomass/biofuel burning and fossil fuel combustion, J. Geophys. Res. Atmos., 108(D15), 4485, doi:10.1029/2002JD003277, 2003. </reference>
		<reference numeration="27" content_type="text"> Hu, C. W., Chao M. R., Wu, K. Y., Chang-Chien, G. P., Lee, W. J., Chang, L. W., and Lee, W. S.: Characterization of multiple airborne particulate metals in the surroundings of a municipal waste incinerator in Taiwan, Atmos. Environ., 37(20), 2845&amp;ndash;2852, 2003. </reference>
		<reference numeration="28" content_type="text"> Jacobson, M. Z.: Analysis of aerosol interactions with numerical techniques for solving coagulation, nucleation, condensation, dissolution, and reversible chemistry among multiple size distributions, J. Geophys. Res. Atmos., 107(D19), 4366, doi:10.1029/2001JD002044, 2002. </reference>
		<reference numeration="29" content_type="text"> Jiang, M., Marr, L. C., Dunlea, E. J., Herndon, S. C., Jayne, J. T., Kolb, C. E., Knighton, W. B., Rogers, T. M., Zavala, M., Molina, L. T., and Molina, M. J.: Vehicle fleet emissions of black carbon, polycyclic aromatic hydrocarbons, and other pollutants measured by a mobile laboratory in Mexico City, Atmos. Chem. Phys., 5, 3377&amp;ndash;3387, 2005. </reference>
		<reference numeration="30" content_type="text"> Jimenez, J. C., Raga, G. B., Baumgardner, D., Castro, T., Rosas, I., Baez, A., and Morton, O.: On the composition of airborne particles influenced by emissions of the volcano Popocatepetl in Mexico, Natural Hazards, 31(1), 21&amp;ndash;37, 2004. </reference>
		<reference numeration="31" content_type="text"> Johnson, K. S., de Foy, B., Zuberi, B., Molina, L. T., Molina, M. J., Xie, Y., Laskin, A., and Shutthanandan, V.: Aerosol composition and source apportionment in the Mexico City Metropolitan Area with PIXE/PESA/STIM and multivariate analysis, Atmos. Chem. Phys., 6, 4591&amp;ndash;4600, 2006. </reference>
		<reference numeration="32" content_type="text"> Johnson, K. S., Zuberi, B., Molina, L. T., Molina, M. J. , Iedema, M. J., Cowin, J. P., Gaspar, D. J., Wang, C., and Laskin, A.: Processing of soot in an urban environment: case study from the Mexico City Metropolitan Area, Atmos. Chem. Phys., 5, 3033&amp;ndash;3043, 2005. </reference>
		<reference numeration="33" content_type="text"> Kanakidou, M., Seinfeld, J. H., Pandis, S. N., Barnes, I., Dentener, F. J., Facchini, M. C., Van Dingenen, R., Ervens, B., Nenes, A., Nielsen, C. J. , Swietlicki, E., Putaud, J. P., Balkanski, Y., Fuzzi, S., Horth, J., Moortgat, G. K., Winterhalter, R., Myhre, C. E. L., Tsigaridis, K., Vignati, E., Stephanou, E. G., and Wilson, J.: Organic aerosol and global climate modelling: a review, Atmos. Chem. Phys., 5, 1053&amp;ndash;1123, 2005. </reference>
		<reference numeration="34" content_type="text"> Kawamura, K. and Ikushima, K.: Seasonal changes in the distribution of dicarboxylic acids in the urban atmosphere, Environ. Sci. Technol. , 27(10), 2227&amp;ndash;2235, 1993. </reference>
		<reference numeration="35" content_type="text"> Kawamura, K. and Kaplan, I. R. : Motor exhaust emissions as a primary source for dicarboxylic-acids in Los-Angeles ambient air, Environ. Sci. Technol. , 21(1), 105&amp;ndash;110, 1987. </reference>
		<reference numeration="36" content_type="text"> Krueger, B. J., Grassian, V. H., Cowin, J. P., and Laskin, A.: Heterogeneous chemistry of individual mineral dust particles from different dust source regions: the importance of particle mineralogy, Atmos. Environ., 38(36), 6253&amp;ndash;6261, 2004. </reference>
		<reference numeration="37" content_type="text"> Laskin, A., Wietsma, T. W., Krueger, B. J., and Grassian, V. H.: Heterogeneous chemistry of individual mineral dust particles with nitric acid: A combined CCSEM/EDX, ESEM, and ICP-MS study, J. Geophys. Res. Atmos., 110(D10), 10208, doi:10.1029/2004JD005206, 2005. </reference>
		<reference numeration="38" content_type="text"> Liu, D. Y., Wenzel, R. J., and Prather, K. A. : Aerosol time-of-flight mass spectrometry during the Atlanta Supersite Experiment: 1. Measurements, J. Geophys. Res. Atmos., 108(D7), 8426, doi:10.1029/2001JD001562, 2003. </reference>
		<reference numeration="39" content_type="text"> Marr, L. C., Dzepina, K. , Jimenez, J. L., Reisen, F., Bethel, H. L., Arey, J., Gaffney, J. S., Marley, N. A., Molina, L. T., and Molina, M. J.: Sources and transformations of particle-bound polycyclic aromatic hydrocarbons in Mexico City, Atmos. Chem. Phys., 6, 1733&amp;ndash;1745, 2006. </reference>
		<reference numeration="40" content_type="text"> Miranda, J., V. A. Barrera, A. A. Espinosa, O. S. Galindo, A. Nunez-Orosco, R. C. Montesinos, A. Leal-Castro, and J. Meinguer: PIXE analysis of atmospheric aerosols from three sites in Mexico City, Nucl. Instrum. Methods Phys. Res., Sect B, 219&amp;ndash;20, 157&amp;ndash;160, 2004. </reference>
		<reference numeration="41" content_type="text"> Miranda, J., Cahill, T. A., Morales, J. R., Aldape, F., Flores, J., and Diaz, R. V.: Determination of elemental concentrations in atmospheric aerosols in Mexico-City usingproton-induced X-Ray emission, proton elastic-scattering, and laser-absorption, Atmos. Environ., 28(14), 2299&amp;ndash;2306, 1994. </reference>
		<reference numeration="42" content_type="text"> Miranda, J., Lopez-Suarez, A., Paredes-Gutierrez, R., Gonzalez, S., de Lucio, O. G., Andrade, E., Morales, J. R., and Avila-Sobarzo, M. J.: A study of atmospheric aerosols from five sites in Mexico city using PIXE, Nucl. Instrum. Methods Phys. Res., Sect B, 137, 970&amp;ndash;974, 1998. </reference>
		<reference numeration="43" content_type="text"> Miranda, J., Morales, J. R., Cahill, T. A., Aldape F., and Flores, J.: A Study of Elemental Contents in Atmospheric Aerosols in Mexico-City, Atmosfera, 5(2), 95&amp;ndash;108, 1992. </reference>
		<reference numeration="44" content_type="text"> Moffet, R. C. and Prather, K. A.: Extending ATOFMS measurements to include refractive index and density, Anal. Chem., 77(20), 6535&amp;ndash;6541, 2005. Molina, L. T. and Molina, M. J.: Air Quality in the Mexico Megacity: An Integrated Assessment, Kluwer Academic Publishers, Boston, 1&amp;ndash;384, 2002. </reference>
		<reference numeration="45" content_type="text"> Morawska, L. and Zhang, J. F.: Combustion sources of particles. 1. Health relevance and source signatures, Chemosphere, 49(9), 1045&amp;ndash;1058, 2002. </reference>
		<reference numeration="46" content_type="text"> Moya, M., Ansari, A. S., and Pandis, S. N.: Partitioning of nitrate and ammonium between the gas and particulate phases during the 1997 IMADA-AVER study in Mexico City, Atmos. Environ., 35(10), 1791&amp;ndash;1804, 2001. </reference>
		<reference numeration="47" content_type="text"> Moya, M., Castro, T., Zepeda, M., and Baez, A.: Characterization of size-differentiated inorganic composition of aerosols in Mexico City, Atmos. Environ., 37(25), 3581&amp;ndash;3591, 2003. </reference>
		<reference numeration="48" content_type="text"> Moya, M., Grutter, M., and Baez, A.: Diurnal variability of size-differentiated inorganic aerosols and their gas-phase precursors during January and February of 2003 near downtown Mexico City, Atmos. Environ., 38(33), 5651&amp;ndash;5661, 2004. </reference>
		<reference numeration="49" content_type="text"> Mugica, V., Maubert, M., Torres, M., Munoz, J., and Rico, E.: Temporal and spatial variations of metal content in TSP and PM10 in Mexico City during 1996&amp;ndash;1998, J. Aerosol Sci., 33(1), 91&amp;ndash;102, 2002. </reference>
		<reference numeration="50" content_type="text"> Noble, C. A. and Prather, K. A.: Real-time measurement of correlated size and composition profiles of individual atmospheric aerosol particles, Environ. Sci. Technol., 30(9), 2667&amp;ndash;2680, 1996. </reference>
		<reference numeration="51" content_type="text"> Olmez, I., Sheffield, A. E., Gordon, G. E., Houck, J. E., Pritchett, L. C., Cooper, J. A., Dzubay, T. G., and Bennett, R. L.: Compositions of particles from selected sources in philadelphia for receptor modeling applications, JAPCA-the International Journal of Air Pollution Control and Hazardous Waste Management, 38(11), 1392&amp;ndash;1402, 1988. </reference>
		<reference numeration="52" content_type="text"> Ondov, J. M. and Wexler, A. S.: Where do particulate toxins reside? An improved paradigm for the structure and dynamics of the urban mid-Atlantic aerosol, Environ. Sci. Technol., 32(17), 2547&amp;ndash;2555, 1998. </reference>
		<reference numeration="53" content_type="text"> Pastor, S. H., Allen, J. O., Hughes, L. S., Bhave, P., Cass, G. R., and Prather, K. A.: Ambient single particle analysis in Riverside, California by aerosol time-of-flight mass spectrometry during the SCOS97-NARSTO, Atmos. Environ., 37, S239&amp;ndash;S258, 2003. </reference>
		<reference numeration="54" content_type="text"> Pitts, J. N., Grosjean, D., Vancauwenberghe, K., Schmid, J. P., and Fitz, D. R.: Photo-oxidation of aliphatic-amines under simulated atmospheric conditions - formation of nitrosamines, nitramines, amides, and photo-chemical oxidant, Environ. Sci. Technol., 12(8), 946&amp;ndash;953, 1978. </reference>
		<reference numeration="55" content_type="text"> Qin, X. Y., Bhave, P. V., and Prather, K. A.: Comparison of two methods for obtaining quantitative mass concentrations from aerosol time-of-flight mass spectrometry measurements, Anal. Chem., 78(17), 6169&amp;ndash;6178, 2006. </reference>
		<reference numeration="56" content_type="text"> Qin, X. Y. and Prather, K. A.: Impact of biomass emissions on particle chemistry during the California Regional Particulate Air Quality Study,Int. J. Mass Spectrom., 258 (1&amp;ndash;3), 142&amp;ndash;150, 2006. </reference>
		<reference numeration="57" content_type="text"> Raga, G.B., Baumgardner, D., Castro, T., Martinez-Arroyo, A., and Navarro-Gonzalez, R.: Mexico City air quality: a qualitative review of gas and aerosol measurements (1960&amp;ndash;2000), Atmos. Environ., 35(23), 4041&amp;ndash;4058, 2001. </reference>
		<reference numeration="58" content_type="text"> Salcedo, D., Onasch, T. B., Dzepina, K., Canagaratna, M. R., Zhang, Q., Huffman, J. A., DeCarlo, P. F. , Jayne, J. T., Mortimer, P., Worsnop, D. R., Kolb, C. E., Johnson, K. S., Zuberi, B., Marr, L. C., Volkamer, R., Molina, L. T., Molina, M. J., Cardenas, B., Bernabe, R. M., Marquez, C., Gaffney, J. S., Marley, N. A., Laskin, A., Shutthanandan, V., Xie, Y., Brune, W. , Lesher, R., Shirley, T., and Jimenez, J. L.: Characterization of ambient aerosols in Mexico City during the MCMA-2003 campaign with Aerosol Mass Spectrometry: results from the CENICA Supersite, Atmos. Chem. Phys., 6, 925&amp;ndash;946, 2006. </reference>
		<reference numeration="59" content_type="text"> Schlesinger, W. H. and Hartley, A. E.: A Global Budget for Atmospheric NH3, Biogeochemistry, 15(3), 191&amp;ndash;211, 1992. </reference>
		<reference numeration="60" content_type="text"> Seibert, P., Kromp-Kolb, H., Baltensperger, U., Jost, D. T., and Schwikowski, M.: Trajectory analysis of high-alpine air pollution data, in, Plenum Press, New York, 1994. </reference>
		<reference numeration="61" content_type="text"> Silva, P. J., Liu, D. Y., Noble, C. A., and Prather, K. A.: Size and chemical characterization of individual particles resulting from biomass burning of local Southern California species, Environ. Sci. Technol., 33(18), 3068&amp;ndash;3076, 1999. </reference>
		<reference numeration="62" content_type="text"> Silva, P. J. and Prather, K. A.: Source profiling and apportionment of airborne particles: A new approach using aerosol time-of-filght mass sepctrometry, University of California, Riverside, Riverside, 189&amp;ndash;208, 2000. </reference>
		<reference numeration="63" content_type="text"> Sodeman, D. A., Toner, S. M., and Prather, K. A.: Determination of single particle mass spectral signatures from light-duty vehicle emissions, Environ. Sci. Technol., 39(12), 4569&amp;ndash;4580, 2005. </reference>
		<reference numeration="64" content_type="text"> Song, X. H., Hopke, P. K., Fergenson, D. P., and Prather, K. A.: Classification of single particles analyzed by ATOFMS using an artificial neural network, ART-2A, Anal. Chem., 71(4), 860&amp;ndash;865, 1999. </reference>
		<reference numeration="65" content_type="text"> Stohl, A., Forster, C. , Frank, A., Seibert, P., and Wotawa, G.: Technical note: The Lagrangian particle dispersion model FLEXPART version 6.2, Atmos. Chem. Phys., 5, 2461&amp;ndash;2474, 2005. </reference>
		<reference numeration="66" content_type="text"> Suarez, A. E. and Ondov, J. M.: Ambient aerosol concentrations of elements resolved by size and by source: Contributions of some cytokine-active metals from coal- and oil-fired power plants, Energy and Fuels, 16(3), 562&amp;ndash;568, 2002. </reference>
		<reference numeration="67" content_type="text"> Sullivan, R. C., Guazzotti, S. A., Sodeman, D. A., and Prather, K. A.: Direct observations of the atmospheric processing of Asian mineral Dust, Atmos. Chem. Phys., 7, 1213&amp;ndash;1236, 2007. </reference>
		<reference numeration="68" content_type="text"> Tolocka, M. P., Lake, D. A., Johnston, M. V., and Wexler, A. S.: Number concentrations of fine and ultrafine particles containing metals, Atmos. Environ., 38(20), 3263&amp;ndash;3273, 2004. </reference>
		<reference numeration="69" content_type="text"> Toner, S. M., Sodeman, D. A., and Prather, K. A.: Single particle characterization of ultrafine and accumulation mode particles from heavy duty diesel vehicles using aerosol time-of-flight mass spectrometry, Environ. Sci. Technol., 40(12), 3912&amp;ndash;3921, 2006. </reference>
		<reference numeration="70" content_type="text"> Vega, E., Mugica, V., Reyes, E., Sanchez, G., Chow, J. C., and Watson, J. G.: Chemical composition of fugitive dust emitters in Mexico City, Atmos. Environ., 35(23), 4033&amp;ndash;4039, 2001. </reference>
		<reference numeration="71" content_type="text"> Vega, E., Reyes, E., Sanchez, G., Ortiz, E., Ruiz, M., Chow, J., Watson, J., and Edgerton, S.: Basic statistics of PM2.5 and PM10 in the atmosphere of Mexico city, Sci. Total Environ., 287(3), 167&amp;ndash;176, 2002. </reference>
		<reference numeration="72" content_type="text"> Wenzel, R. J., Liu, D. Y., Edgerton, E. S., and Prather, K. A.: Aerosol time-of-flight mass spectrometry during the Atlanta Supersite Experiment: 2. Scaling procedures, J. Geophys. Res. Atmos., 108(D7), 8424, doi:10.1029/2001JD001563, 2003. </reference>
		<reference numeration="73" content_type="text">Yao, X. H., Fang, M., and Chan, C. K.: Size distributions and formation of dicarboxylic acids in atmospheric particles, Atmos. Environ., 36(13), 2099&amp;ndash;2107, 2002. </reference>
	</references>
</article>

