エアロゾル研究

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1 Feature Article Earozoru Kenkyu, 26 4, Soot-Containing Particles in the Atmosphere: Modifications of Morphology and Mixing States with Water-Soluble Materials Sayako UEDA 1 * Received 31 May 2011 Accepted 10 November 2011 Abstract This study focused on modification effects of soot-containing particles by aging and incloud scavenging processes. Morphological features and mixing states with water-soluble materials of soot-containing particles collected at two observation sites were analyzed by a transmission electron microscopy (TEM) with extraction of water-soluble materials. To elucidate the aging effects after their transport from megacities, we obtained aerosol samples for continental outflow at Cape Hedo, Okinawa in March Most soot-containing particles ( μm) were mixed with water-soluble materials. Some soot-containing particles were found as clustered particles in multiple small (ca. 0.3 μm) spheroids. They were attributed to coagulation of solid spheroidal particles. At Mt. Tateyama (2300 m a.s.l.) in June 2007, cloud interstitial particles were measured using fog (>10 μm)-cut inlets. During fog condition under high precipitation (2 6 mm/hr), most of cloud interstitial particles ( μm) were less- or non-hygroscopic particles. The results of TEM analysis suggested that most of the cloud interstitial particles were soot particles without water-soluble materials. These observation results suggested that morphological modification with coagulation process under high aerosol concentration and population change of the particles with in-cloud scavenging process are key processes controlling morphology and mixing states of soot-containing particles in the atmosphere. These changes of soot-containing particles must be considered when estimating direct radiation effect of aerosols from megacities and assessing climatic effects by long range transport of soot aerosols. Keywords : Atmospheric Aerosol, Microscopic Analysis, Aging Process, Coagulation, In-Cloud Scavenging. 1, Tokyo University of Science 1-3 Kagurazaka Shinjuku Tokyo * Corresponding Author. ueda@rs.tus.ac.jp (S. Ueda) ,4 5,

2 m 9 4 nm 10 Okada 11 Pt/Pd arctan 0.5 Pt/Pd μm Optical Particle Counter OPC, KC-18; Rion Particle Soot Absorption Photometer PSAP Radiance Research BC 0.5 μm 0.5 μm μm less-grown LG OPC 9 Takami 12 Takiguchi 13 Q-AMS; Aerodyne Research PM Fig. 1 Fig. 1 Temporal variations of (a) potential area of air mass origin, (b) volume concentrations of aerosols for μm diameter and sampling times (A F with bars) and (c) size-segregated black carbon mass concentration. Vol. 26 No

BC 24 26 28 Fig. 1 B, D, F BC 0.3 μm 0.3 μm Fig. 1 A-F Fig. 2 Fig. 2a 10 nm Type 1 Fig. 2c 0.3 μm Type 5 Fig. 2a c Type 1 Type 5 10 nm Fig. 2a Fig.

of (a), (b), (c), and (d). White arrows indicate morphological types. White dotted lines represent dimensions of particles before water dialysis. Black arrows indicate insoluble-soot cores. Fig.

3 BC Fig. 1 B, D, F BC 0.3 μm 0.3 μm Fig. 1 A-F Fig. 2 Fig. 2a 10 nm Type 1 Fig. 2c 0.3 μm Type 5 Fig. 2a c Type 1 Type 5 10 nm Fig. 2a Fig. 2 Electron micrographs before and after water dialysis for Type 1 5 particles: (a), (b), (c) and (d) before water dialysis; (a ), (b ), (c ), and (d ) after dialysis with water for the same regions of (a), (b), (c), and (d). White arrows indicate morphological types. White dotted lines represent dimensions of particles before water dialysis. Black arrows indicate insoluble-soot cores. Fig. 2a μm 2 25% μm 14 59% 1% μm 5 Type 1 Type 2 Type 3 Type 4 Type μm X Type 1 C Type S Q-AMS Cl - NO 3- SO 2-4 NH 4+ SO 2-4 NH 4+ 90% SO 2-4 Type Fig. 3a A C Type 2 3 B D E F 0.4 μm Type μm Type 5 Type 5 Type 4 Q-AMS A C NH 4 HSO 4 B D E F (NH 4 ) 2 SO 4 A C NH 4 HSO 4 39% 14 B D E F (NH 4 ) 2 SO 4 80% 15 Fig. 3b A C Type 2 3 B D E F 0.4 μm Type μm Type 5 Fig. 3a Type μm

4 Fig. 3 Number proportions of morphological types of (a) particles and (b) soot-containing particles, for samples A F. Numbers above columns show the number of particles observed. 10 μm LG Fig Fig. 4b 2 6 mm/hr μm LG 100 Fig. 4a c BC 0.4 μm Fig. 4d μm 0.4 μm BC 70% Fig. 4e 1 mm/hr LG 50% μm 0.4 μm BC 20 Fig. 4 I, II, III LG I, II Fig. 5 I III LG 20% II μm 9 BC Vol. 26 No

$5 μm in diameter, (c) number fraction of LG particles with 0.3 0.5 μm in diameter, (d) black carbon mass concentration, and (e) ratio in % of black carbon volume (V BC <0.$

5 Fig. 4 Temporal variations of (a) precipitation at Kamiichi, (b) number (black and gray lines) and volume (area plot) concentrations of aerosols with μm in diameter, (c) number fraction of LG particles with μm in diameter, (d) black carbon mass concentration, and (e) ratio in % of black carbon volume (V BC <0.4 ) per particle volume (V p ). Durations of rain and fog, and sampling period were shown as bars. Fig. 5 Electron micrograph of cloud interstitial samples I and II: (a, b) before and (a, b ) after dialysis with water for the same sample region

6 PSAP References 1) 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 (2004) 2) Ramanathan, V. and Carmichael, G.: Global and Regional Climate Changes due to Black Carbon, Nature Geoscience, 1, (2008) 3) Weingartner. E., Burtscher, H. and Baltensperger, U.: Hygroscopic Properties of Carbon and Diesel Soot Particles, Atmos. Environ., 31, (1997) 4) Khalizov, A. F., Zhang, R., Zhang, D., Xue, H., Pagels, J. and McMurry, P. H.: Formation of Highly Hygroscopic Soot Aerosols upon Internal Mixing with Sulfuric Acid Vapor, J. Geophys. Res., 114, D05208 (2009) 5) Khalizov, A. F., Xue, H., Wang, L., Zheng, J. and Zhang, R.: Enhanced Light Absorption and Scattering by Carbon Soot Aerosol Internally Mixed with Sulfulic Acid, J. Phys. Chem., 113, (2009) 6) Adachi, K., Chung, S. H. and Buseck, P. R.: Shapes of Soot Aerosol Particles and Implications for Their Effects on Climate, J. Geophys. Res., 115, D15206 (2010) 7) Koch, D. and Hansen, J.: Distant Origins of Arctic Black Carbon: A Goddard Institute for Space Studies Model E Experiment, J. Geophys. Res., 110, D04204 (2005) 8) Ueda, S., Osada, K. and Takami, A.: Morphological Features of Soot-Containing Particles Internally Mixed with Water- Soluble Materials in Continental Outflow Observed at Cape Hedo, Okinawa, Japan, J. Geophys. Res., 116 (2011) 9) Ueda, S., Osada, K. and Okada, K.: Mixing States of Cloud Interstitial Particles between Water-Soluble and Insoluble Materials at Mt. Tateyama, Japan: Effects of Meteorological Conditions, Atmos. Res., 99, (2011) 10) Pósfai, M., Simonics, R., Li, J., Hobbs, P. V. and Buseck, P. R.: Individual Aerosol Particles from Biomass Burning in Southern Africa: 1. Compositions and Size Distributions of Carbonaceous Particles, J. Geophys. Res., 108, D13, 8483 (2003) 11) Okada. K.: Nature of Individual Hygroscopic Particles in the Urban Atmosphere, J. Meteor. Soc. Japan., 61, (1983) 12) Takami, A., Miyoshi, T., Shimono, A., Kaneyasu, N., Kato, S., Kajii, Y. and Hatakeyama, S.: Transport of Anthropogenic Aerosols from Asia and Subsequent Chemical Transformation, J. Geophys. Res., 112, D22S31 (2007) 13) Takiguchi, Y., Takami, A., Lun, X., Shimizu, A., Matsui, I., Sugimoto, N., Wang, W., Bandow, H. and Hatakeyama, S.: Transport and Transformation of Total Reactive Nitrogen over the East China Sea, J. Grophys. Res., 113, D10306 (2008) 14) Tang, I. N. and Munkelwitz, H. R.: Aerosol Growth Studied III Ammonium Bisulfate Aerosol in a Moist Atmosphere, J. Aerosol Sci., 8, (1977) 15) Tang, I. N., Wong, W. T. and Munkelwitz, H. R.: The Relative Importance of Atmospheric Sulfates and Nitrates in Visibility Reduction, Atmos. Environ., 15, (1977) 16) Wu, Z., Hu, M., Lin, P., Liu, S., Wehner, B. and Wiedensohler, A.: Particle Number Size Distribution in the Urban Atmosphere of Beijing, China, Atmos. Environ., 42, (2008) 17) Kasper-Giebl, A., Koch, A., Hitzenberger, R. and Puxbaum, H.: Scavenging Efficiency of Aerosol Carbon and Sulfate in Supercooled Clouds at Mt. Sonnblick (3106 m a.s.l., Austria), J. Atmos. Chem., 35, (2000) 18) Hitzenberger, R., Berner, A., Giebl, H., Drobesch, K., Kasper-Giebl, A., Loeflund, M., Urban, H. and Puxbaum, H.: Black Carbon (BC) in Alpine Aerosols and Cloud Water Concentrations and Scavenging Efficiencies, Atmos. Environ., 35, (2001) 19) Cozic, J., Verheggen, B., Mertes, S., Connolly, P., Bower, K., Petzold, A., Baltensperger, U. and Weingartner, E.: Scavenging of Black Carbon in Mixed Phase Clouds at the High Alpine Site Jungfraujoch, Atmos. Chem. Phys., 7, (2007) Vol. 26 No

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