ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-10-21521-2010 The relationship between 0.25–2.5 μm aerosol and CO<sub>2</sub> emissions over a city Vogt M. 1 Nilsson E. D. 1 Ahlm L. 1 Mårtensson E. M. 1 Johansson C. 1 2 Department of Applied Environmental Science (ITM), Stockholm University, 10691 Stockholm, Sweden City of Stockholm Environment and Health Administration, Box 8136, 10420 Stockholm, Sweden 09 09 2010 10 9 21521 21545 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-discuss.net/10/21521/2010/acpd-10-21521-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/10/21521/2010/acpd-10-21521-2010.pdf

Unlike exhaust emissions, non-exhaust traffic emissions are completely unregulated and there are large uncertainties in the non-exhaust emission factors required to estimate the emissions of these aerosols. This study provides the first published results of direct measurements of size resolved emission factors for particles in the size range 0.25–2.5 μm using a new approach deriving aerosol emission factors from the CO<sub>2</sub> emission fluxes. Because the aerosol and CO<sub>2</sub> emissions have a common source and because the CO<sub>2</sub> emission per fuel or traffic amount are much less uncertain than the aerosol emissions, this approach has obvious advantages. Therefore aerosol fluxes were measured during one year using the eddy covariance method at the top of a 118 m high communication tower over Stockholm, Sweden. Maximum CO<sub>2</sub> and particle fluxes coincides with the wind direction with densest traffic within the footprint area. Negative fluxes (uptake of CO<sub>2</sub> and deposition of particles) coincides with an urban forest area. The fluxes of CO<sub>2</sub> were used to obtain emission factors for particles by assuming that the CO<sub>2</sub> fluxes could converted to amounts of fuel burnt. The estimated emission factors for the fleet mix in the measurement area are, in number 1.4×10<sup>11</sup> [particle veh<sup>−1</sup> km<sup>−1</sup>]. Assuming spherical particles of density 1600 kg/m<sup>3</sup> this corresponds to 27.5 mg veh<sup>−1</sup> km<sup>−1</sup>. Wind speed influence the emission factor indicating that wind induced turbulence may be important.

 References Areskoug, H., Camner, P., Dahlen, S. E., Lastbom, L., Nyberg, F., Pershagen, G., and Sydbom, A.: Particles in ambient air – a health risk assessment, Scand. J. Work. Env. Hea., 26, 1–96, 2000. Buzorius, G., Rannik, U., Makela, J. M., Keronen, P., Vesala, T., and Kulmala, M.: Vertical aerosol fluxes measured by the eddy covariance method and deposition of nucleation mode particles above a Scots pine forest in southern Finland, J. Geophys. Res-Atmos., 105, 19905–19916, 2000. Colberg, C. A., Tona, B., Stahel, W. A., Meier, M., and Staehelin, J.: Comparison of a road traffic emission model (HBEFA) with emissions derived from measurements in the Gubrist road tunnel, Switzerland, Atmos. Environ., 39, 4703–4714, 2005. Coutts, A. M., Beringer, J., and Tapper, N. J.: Characteristics influencing the variability of urban CO2 fluxes in Melbourne, Australia, Atmos. Environ., 41, 51–62, 2007. Dorsey, J. R., Nemitz, E., Gallagher, M. W., Fowler, D., Williams, P. I., Bower, K. N., and Beswick, K. M.: Direct measurements and parameterisation of aerosol flux, concentration and emission velocity above a city, Atmos. Environ., 36, 791–800, 2002. Fratini, G., Ciccioli, P., Febo, A., Forgione, A., and Valentini, R.: Size-segregated fluxes of mineral dust from a desert area of northern China by eddy covariance, Atmos. Chem. Phys., 7, 2839–2854, doi:10.5194/acp-7-2839-2007, 2007. Gehrig, R. and Buchmann, B.: Characterizing seasonal variations and spatial distribution of ambient PM10 and PM2.5 concentrations based on long-term Swiss monitoring data, Atmos. Environ., 37, 2571–2580, 2003. Gidhagen, L., Johansson, C., Langner, J., and Foltescu, V. L.: Urban scale modeling of particle number concentration in Stockholm, Atmos. Environ., 39, 1711–1725, doi:10.1016/j.atmosenv.2004.11.042, 2005. Gillette, D. A., Adams, J., Endo, A., Smith, D., and Kihl, R.: Threshold Velocities for Input of Soil Particles into the Air by Desert Soils, J. Geophys. Res-Oc. Atm., 85, 5621–5630, 1980. Grimmond, C. S. B., King, T. S., Cropley, F. D., Nowak, D. J., and Souch, C.: Local-scale fluxes of carbon dioxide in urban environments: methodological challenges and results from Chicago, Environ. Pollut., 116, 243–254, 2002. Hall, E., Ramamurthy, S. S., and Balda, J. C.: Optimum speed ratio of induction motor drives for electrical vehicle propulsion, Appl. Power Elect. Co., 371–377, 1314, 2001. Harrison, R. M., Shi, J. P., Xi, S. H., Khan, A., Mark, D., Kinnersley, R., and Yin, J. X.: Measurement of number, mass and size distribution of particles in the atmosphere, Philos. T. Roy Soc. A., 358, 2567–2579, 2000. Horst, T. W.: A simple formula for attenuation of eddy fluxes measured with first-order-response scalar sensors, Bound-Lay. Meteorol., 82, 219–233, 1997. Hueglin, C., Buchmann, B., and Weber, R. O.: Long-term observation of real-world road traffic emission factors on a motorway in Switzerland, Atmos. Environ., 40, 3696–3709, 2006. Jamriska, M. and Morawska, L.: A model for determination of motor vehicle emission factors from on-road measurements with a focus on submicrometer particles, Sci. Total Environ., 264, 241–255, 2001. Järvi, L., Rannik, Ü., Mammarella, I., Sogachev, A., Aalto, P. P., Keronen, P., Siivola, E., Kulmala, M., and Vesala, T.: Annual particle flux observations over a heterogeneous urban area, Atmos. Chem. Phys., 9, 7847–7856, doi:10.5194/acp-9-7847-2009, 2009. Keogh, D. U., Ferreira, L., and Morawska, L.: Development of a particle number and particle mass vehicle emissions inventory for an urban fleet, Environ. Modell Softw., 24, 1323–1331, 2009. Kerminen, V. M., Pakkanen, T. A., Makela, T., Hillamo, R. E., Sillanpaa, M., Ronkko, T., Virtanen, A., Keskinen, J., Pirjola, L., Hussein, T., and Hameri, K.: Development of particle number size distribution near a major road in Helsinki during an episodic inversion situation, Atmos. Environ., 41, 1759–1767, 2007. Ketzel, M., Wahlin, P., Berkowicz, R., and Palmgren, F.: Particle and trace gas emission factors under urban driving conditions in Copenhagen based on street and roof-level observations, Atmos. Environ., 37, 2735–2749, 2003. Kirchstetter, T. W., Harley, R. A., Kreisberg, N. M., Stolzenburg, M. R., and Hering, S. V.: On-road measurement of fine particle and nitrogen oxide emissions from light- and heavy-duty motor vehicles, Atmos. Environ., 33, 2955–2968, 1999. Kittelson, D. B., Watts, W. F., and Johnson, J. P.: Nanoparticle emissions on Minnesota highways, Atmos. Environ., 38, 9–19, 2004. Kristensson, A., Johansson, C., Westerholm, R., Swietlicki, E., Gidhagen, L., Wideqvist, U., and Vesely, V.: Real-world traffic emission factors of gases and particles measured in a road tunnel in Stockholm, Sweden, Atmos. Environ., 38, 657–673, 2004. Lenschow, D. H. and Raupach, M. R.: The Attenuation of Fluctuations in Scalar Concentrations through Sampling Tubes, J. Geophys. Res-Atmos., 96, 15259–15268, 1991. Mårtensson, E. M., Nilsson, E. D., Buzorius, G., and Johansson, C.: Eddy covariance measurements and parameterisation of traffic related particle emissions in an urban environment, Atmos. Chem. Phys., 6, 769–785, doi:10.5194/acp-6-769-2006, 2006. Martin, C. L., Longley, I. D., Dorsey, J. R., Thomas, R. M., Gallagher, M. W., and Nemitz, E.: Ultrafine particle fluxes above four major European cities, Atmos. Environ., 43, 4714–4721, 2009. McLaren, R., Gertler, A. W., Wittorff, D. N., Belzer, W., Dann, T., and Singleton, D. L.: Real-world measurements of exhaust and evaporative emissions in the Cassiar tunnel predicted by chemical mass balance modeling, Environ. Sci. Technol., 30, 3001–3009, 1996. Nemitz, E., Fowler, D., Gallagher, M. W., Dorsey, J. R., Theobald, M. R., and Bower, K.: Measurement and interpretation of land-atmosphere aerosol fluxes: current issues and new approaches, edited by: Midgley, P. M., Reuther, M., and Williams, M., Proceedings of EUROTRAC Symposium 2000, Springer Verlag Berlin, Heidelberg, 45–53, 2001. Nemitz, E., Hargreaves, K. J., McDonald, A. G., Dorsey, J. R., and Fowler, D.: Meteorological measurements of the urban heat budget and CO2 emissions on a city scale, Environ. Sci. Technol., 36, 3139–3146, 2002. Norman, M. and Johansson, C.: Studies of some measures to reduce road dust emissions from paved roads in Scandinavia, Atmos. Environ., 40, 6154–6164, 2006. Omstedt, G., Bringfelt, B., and Johansson, C.: A model for vehicle-induced non-tailpipe emissions of particles along Swedish roads, Atmos. Environ., 39, 6088–6097, 2005. Pitz, M., Cyrys, J., Karg, E., Wiedensohler, A., Wichmann, H. E., and Heinrich, J.: Variability of apparent particle density of an urban aerosol, Environ. Sci. Technol., 37, 4336–4342, 2003. Ruuskanen, J., Tuch, T., Ten Brink, H., Peters, A., Khlystov, A., Mirme, A., Kos, G. P. A., Brunekreef, B., Wichmann, H. E., Buzorius, G., Vallius, M., Kreyling, W. G., and Pekkanen, J.: Concentrations of ultrafine, fine and PM2.5 particles in three European cities, Atmos. Environ., 35, 3729–3738, 2001. Sjodin, A. and Lenner, M.: On-Road Measurements of Single Vehicle Pollutant Emissions, Speed and Acceleration for Large Fleets of Vehicles in Different Traffic Environments, Sci. Total Environ., 169, 157–165, 1995. Sjogren, M., Li, H., Banner, C., Rafter, J., Westerholm, R., and Rannug, U.: Influence of physical and chemical characteristics of diesel fuels and exhaust emissions on biological effects of particle extracts: A multivariate statistical analysis of ten diesel fuels, Chem. Res. Toxicol., 9, 197–207, 1996. Tunved, P., Nilsson, E. D., Hansson, H.-C., and Ström, J.: Aerosol characteristics of air masses in northern Europe: Influences of location, transport, sinks, and sources, J. Geophys. Res. 110, D07201, doi:10.1029/2004JD005085, 2005. Velasco, E., Pressley, S., Allwine, E., Westberg, H., and Lamb, B.: Measurements of CO2 fluxes from the Mexico City urban landscape, Atmos. Environ., 39, 7433–7446, 2005. Vogt, M., Nilsson, E.D., Ahlm, L., Mårtensson, M., and Johansson, C.: Seasonal and diurnal cycles of 0.25-2.5 μm aerosol and CO<sub>2</sub> fluxes over urban Stockholm, Sweden, Tellus B, in review, 2010. Vogt, R., Christen, A., Rotach, M. W., Roth, M., and Satyanarayana, A. N. V.: Temporal dynamics of CO2 fluxes and profiles over a central European city, Theor. Appl. Climatol., 84, 117–126, 2006. Webb, E. K., Pearman, G. I., and Leuning, R.: Correction of Flux Measurements for Density Effects Due to Heat and Water-Vapor Transfer, Q. J. Roy. Meteor. Soc., 106, 85–100, 1980. Westerholm, R. and Egeback, K. E.: Exhaust Emissions from Light-Duty and Heavy-Duty Vehicles – Chemical-Composition, Impact of Exhaust after Treatment, and Fuel Parameters, Environ. Health Persp., 102, 13–23, 1994.