ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-10-9237-2010 Role of dust alkalinity in acid mobilization of iron Ito A. 1 Feng Y. 2 Research Institute for Global Change, JAMSTEC, Yokohama, Kanagawa, 236-0001, Japan Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0221, USA 01 10 2010 10 19 9237 9250 Copyright: © 2010 A. Ito 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://acp.copernicus.org/articles/10/9237/2010/acp-10-9237-2010.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/10/9237/2010/acp-10-9237-2010.pdf

Atmospheric processing of mineral aerosols by acid gases (e.g., SO<sub>2</sub>, HNO<sub>3</sub>, N<sub>2</sub>O<sub>5</sub>, and HCl) may play a key role in the transformation of insoluble iron (Fe in the oxidized or ferric (III) form) to soluble forms (e.g., Fe(II), inorganic soluble species of Fe(III), and organic complexes of iron). On the other hand, mineral dust particles have a potential of neutralizing the acidic species due to the alkaline buffer ability of carbonate minerals (e.g., CaCO<sub>3</sub> and MgCO<sub>3</sub>). Here we demonstrate the impact of dust alkalinity on the acid mobilization of iron in a three-dimensional aerosol chemistry transport model that includes a mineral dissolution scheme. In our model simulations, most of the alkaline dust minerals cannot be entirely consumed by inorganic acids during the transport across the North Pacific Ocean. As a result, the inclusion of alkaline compounds in aqueous chemistry substantially limits the iron dissolution during the long-range transport to the North Pacific Ocean: only a small fraction of iron (<0.2%) dissolves from hematite in the coarse-mode dust aerosols with 0.45% soluble iron initially. On the other hand, a significant fraction of iron (1–2%) dissolves in the fine-mode dust aerosols due to the acid mobilization of the iron-containing minerals externally mixed with carbonate minerals. Consequently, the model quantitatively reproduces higher iron solubility in smaller particles as suggested by measurements over the Pacific Ocean. It implies that the buffering effect of alkaline content in dust aerosols might help to explain the inverse relationship between aerosol iron solubility and particle size. We also demonstrate that the iron solubility is sensitive to the chemical specification of iron-containing minerals in dust. Compared with the dust sources, soluble iron from combustion sources contributes to a relatively marginal effect for deposition of soluble iron over the North Pacific Ocean during springtime. Our results suggest that more comprehensive data for chemical specificity of iron-rich dust is needed to improve the predictive capability for size-segregated soluble iron particles.

 References Andronova, A. V., Gomes, L., Smirnov, V. V., Ivanov, A. V., and Shukurova, L. M.: Physicochemical characteristics of dust aerosols deposited during the Soviet-American eperiment (Tajikistan, 1989), Atmos. Environ., Part A: General Topics, 27(16), 2487–2493, 1993. Arimoto, R., Zhang, X. Y., Huebert, B. J., Kang, C. H., Savoie, D. L., Prospero, J. M., Sage, S. K., Schloesslin, C. A.,Khaing, H. M., and Oh, S. N.: Chemical composition of atmospheric aerosols from Zhenbeitai, China, and Gosan, South Korea, during ACE-Asia, J. Geophys. Res., 109(D19), D19S04, https://doi.org/10.1029/2003JD004323, 2004. Azuma, K. and Kametani, H.: Kinetics of dissolution of ferric oxide, Trans. Metall. Soc. AIME, 230, 853–862, 1964. Baker, A. R. and Croot, P. L.: Atmospheric and marine controls on aerosol iron solubility in seawater, Mar. Chem., 120, 4–13, https://doi.org/10.1016/j.marchem. 2008.09.003, 2010. Baker, A. R. and Jickells{, }T. D.: Mineral particle size as a control on aerosol iron solubility, Geophys. Res. Lett., 33, L17608, https://doi.org/10.1029/2006GL026557, 2006. Blesa, M. A., Morando, P. J., and Regazzoni{, }A. E.: Chemical Dissolution of Metal Oxides, 401 pp., CRC Press, Boca Raton, Fla, 1994. Bopp, L., Monfray, P., Aumont, O., Dufresne, J.-L., LeTreut, H., Madec, G., Terray, L., and Orr, J.: Potential impact of climate change on marine export production. Global Biogeochem. Cy., 15, 81–99, 2001. Buck, C. S., Landing, W. M., and Resing, J. A.: Particle size and aerosol iron solubility: A high-resolution analysis of Atlantic aerosols, Mar. Chem., 20, 14–24, https://doi.org/10.1016/j.marchem.2008.11.002, 2010. Burch, T. E., Nagy, K. L., and Lasaga, A. C.: Free energy dependence of albite dissolution kinetics at 80 °C and pH 8.8, Chem. Geol., 105(1–3), 137–162, 1993. Cama, J., Ayora, C., and Lasaga, A. C.: The deviation-from-equilibrium effect on dissolution rate and on apparent variations in activation energy, Geochim. Cosmochim. Acta, 63(17), 2481–2486, 1999. Capaldo, K. P., Pilinis, C., and Pandis, S. N.: A computationally efficient hybrid approach for dynamic gas/aerosol transfer in air quality models, Atmos. Environ., 34, 3617–3627, 2000. Chen, L.-L., Carmichael, G. R., and Hong, M.-S. et al.: Influence of continental outflow events on the aerosol composition at Cheju Island, South Korea, J. Geophys. Res., 102, 28551–28574, 1997. Chen, Y. and Siefert{,} R.: Determination of various types of labile atmospheric iron over remote oceans, J. Geophys. Res., 108(D24), 4774, https://doi.org/10.1029/2003JD003515, 2003. Chou L., Garrels{,} R. M., and Wollast{,} R.: Comparative study of the kinetics and mechanisms of dissolution of carbonate minerals, Chem. Geol., 78, 269–282, 1989. Chuang, P. Y., Duvall, R. M., Shafer, M. M., and Schauer{,} J. J.: The origin of water soluble particulate iron in the Asian atmospheric outflow, Geophys. Res. Lett., 32, L07813, https://doi.org/10.1029/2004GL021946, 2005. Claquin, T., Schulz, M., and Balkanski, Y. J.: Modeling the mineralogy of atmospheric dust sources, J. Geophys. Res., 104, 22243–22256, 1999. Cornell, R. M. and Schwertmann{, U.:} The Iron Oxides: Structure, Properties, Reactions, Occurrences and Uses, 573 pp., John Wiley, Hoboken, NJ, 1996. Cwiertny, D. M., Baltrusaitis, J., Hunter, G. J., }Laskin, A.{, Scherer, M. M., and Grassian{, }V. H.: Characterization and acid-mobilization study of iron-containing mineral dust source materials, J. Geophys. Res., 113, D05202, https://doi.org/10.1029/2007JD009332, 2008. Dentener, F. J., Carmichael, G. R., Zhang, Y., Lelieveld, J., and Crutzen, P. J.: Role of mineral aerosol as a reactive surface in the global troposphere, J. Geophys. Res., 101(D17), 22869–22889, 1996. Dentener, F., Kinne, S., Bond, T., Boucher, O., Cofala, J., Generoso, S., Ginoux, P., Gong, S., Hoelzemann, J. J., Ito, A., Marelli, L., Penner, J. E., Putaud, J.-P., Textor, C., Schulz, M., van der Werf, G. R., and Wilson, J.: Emissions of primary aerosol and precursor gases in the years 2000 and 1750 prescribed data-sets for AeroCom, Atmos. Chem. Phys., 6, 4321–4344, https://doi.org/10.5194/acp-6-4321-2006, 2006. Duce, R. A. and Tindale, N. W.: Atmospheric transport of iron and its deposition in the ocean, Limnol. Oceanogr., 36(8), 1715–1726, 1991. Duvall, R. M., Majestic, B. J., Shafer, M. M., Chuang, P. Y., Simoneit, B. R. T., and Schauer, J. J.: The water-soluble fraction of carbon, sulfur, and crustal elements in Asian aerosols and Asian soils, Atmos. Environ., 42, 5872–5884, 2008. Fairlie, T. D., Jacob, D. J., Dibb, J. E., Alexander, B., Avery, M. A., van Donkelaar, A., and Zhang, L.: Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes, Atmos. Chem. Phys., 10, 3999–4012, https://doi.org/10.5194/acp-10-3999-2010, 2010. Falkovich, A. H., Ganor, E., Levin, Z., Formenti, P., and Rudich, Y.: Chemical and mineralogical analysis of individual mineral dust particles, J. Geophys. Res., 106, 18029–18036, 2001. Feng, Y. and Penner{, }J. E.: Global modeling of nitrate and ammonium: Interaction of aerosols and tropospheric chemistry, J. Geophys. Res., 112, D01304, https://doi.org/10.1029/2005JD006404, 2007. Fu, H., Cwiertny, D. M., Carmichael, G. R., Scherer, M. M., and Grassian, V. H.: Photoreductive dissolution of Fe–containing mineral dust particles in acidic media, J. Geophys. Res., 115, D11304, https://doi.org/10.1029/2009JD012702, 2010. Fung, I. Y., Meyn, S. K., Tegen, I., Doney, S. C., John, J. G., and Bishop, J. K. B.: Iron supply and demand in the upper ocean, Global Biogeochem. Cy., 14(2), 697–700, 2000. Gao, Y. and Anderson, J. R.: Characteristics of Chinese aerosols determined by individual-particle analysis, J. Geophys. Res., 106, 18037–18045, 2001. Gillette, D. A., Patterson Jr., E. M., Prospero, J. M., and Jackson, M. L.: Soil aerosols, in Aerosol Effects on Climate, edited by S. G. Jennings, 77–109, Univ. of Ariz., Tucson, 1993. Guieu, C., Bonnet, S., Wagener, T., and Loye-Pilot, M.-D: Biomass burning as a source of dissolved iron to the open ocean?, Geophys. Res. Lett., 22, L19608, https://doi.org/10.1029/2005GL022962, 2005. Hand, J. L., Mahowald, N. M., }Chen, Y.{, Siefert, }R. L.{, Luo, C., Subramaniam, A., and Fung{, }I.: Estimates of atmospheric-processed soluble iron from observations and a global mineral aerosol model: Biogeochemical implications, J. Geophys. Res., 109, D17205, https://doi.org/10.1029/2004JD004574, 2004. Hildemann, L., Markowski, G., and Cass, G.: Chemical composition of emissions from urban sources of fine organic aerosol, Environ. Sci. Technol., 25, 744–759, 1991. Huebert, B. J., Bates, T., Russell, P. B., Shi, G., Kim, Y. J., and Kawamura, K., Carmichael, G., and Nakajima, T.: An overview of ACE-Asia: Strategies for quantifying the relationships between Asian aerosols and their climatic impacts, J. Geophys. Res., 108(D23), 8633, https://doi.org/10.1029/2003JD003550, 2003. Hseung, Y. and Jackson, M. L.: Mineral composition of the clay fraction: III Of some main soil groups of China, Soil Sci. Soc. Am. P., 16, 294–297, 1952. Ito, A. and Kawamiya, M.: Potential impact of ocean ecosystem changes due to global warming on marine organic carbon aerosols, Global Biogeochem. Cy., 24, GB1012, https://doi.org/10.1029/2009GB003559, 2010. Ito, A. and Penner, J. E.: Historical emissions of carbonaceous aerosols from biomass and fossil fuel burning for the period 1870–2000, Global Biogeochem. Cy., 19, GB2028, https://doi.org/10.1029/2004GB002374, 2005. Ito, A., Sillman, S., and Penner, J. E.: Effects of additional nonmethane volatile organic compounds, organic nitrates, and direct emissions of oxygenated organic species on global tropospheric chemistry, J. Geophys. Res., 112, D06309, https://doi.org/10.1029/2005JD006556, 2007. Ito, A., Sillman, S., and Penner, J. E.: Global chemical transport model study of ozone response to changes in chemical kinetics and biogenic volatile organic compounds emissions due to increasing temperatures: Sensitivities to isoprene nitrate chemistry and grid resolution, J. Geophys. Res., 114, D09301, https://doi.org/10.1029/2008JD011254, 2009. Iwasaka, Y., Yamato, M., Imasu, R., and Ono{, }A.: Transport of Asian dust (KOSA) particles: importance of weak KOSA events on the geochemical cycle of soil particles, Tellus, 40B, 494–503{, }1988. Jacobson, M. Z.: Studying the effects of calcium and magnesium on size-distributed nitrate and ammonium with EQUISOLV II, Atmos. Environ., 33, 3635–3649{, }1999. Jickells, T. D., An, Z. S., Andersen, K. K., et al.: Global iron connections between desert dust, ocean biogeochemistry, and climate, Science, 308, 67–71, 2005. Journet, E., Desboeufs, K. V., Caquineau, S., and Colin, J.-L.: Mineralogy as a critical factor of dust iron solubility, Geophys. Res. Lett., 35, L07805, https://doi.org/10.1029/2007GL031589, 2008. Kline, J., Huebert, B., Howell, S., Blomquist, B., Zhuang, J., Bertram, T., and Carrillo, J.: Aerosol composition and size versus altitude measured from the C-130 during ACE-Asia, J. Geophys. Res., 109, D19508, https://doi.org/10.1029/2004JD004540, 2004. Krishnamurthy, A., Moore, J. K., Mahowald, N., Luo, C., Doney, S. C., Lindsay, K., and Zender, C. S.: Impacts of increasing anthropogenic soluble iron and nitrogen deposition on ocean biogeochemistry, Global Biogeochem. Cy., 23, GB3016, https://doi.org/10.1029/2008GB003440, 2009. Lasaga, A. C., Soler, J. M., Ganor, J., Burch, T. E., and Nagy, K. L.: Chemical-weathering rate laws and global geochemical cycles, Geochim. Cosmochim. Acta, 58(10), 2361–2386, 1994. Liu, X., Penner, J. E., and Herzog, M.: Global modeling of aerosol dynamics: Model description, evaluation and interactions between sulfate and non-sulfate aerosols, J. Geophys. Res., 110, D18206, https://doi.org/10.1029/2004JD005674, 2005. Luo, C., Mahowald, N., Bond, T., Chuang, P. Y., Artaxo, P., Siefert, R., Chen, Y., and Schauer, J.: Combustion iron distribution and deposition, Global Biogeochem. Cy., 22, GB1012, https://doi.org/10.1029/2007GB002964, 2008. Maenhaut, W., Salma, I., Cafmeyer, J., Annegarn, H. J., and Andreae, M. O.: Regional atmospheric aerosol composition and sources in the eastern Transvaal, South Africa, and impact of biomass burning, J. Geophys. Res., 101, 23631–23650, 1996. Mahowald, N. M., Baker, A. R., Bergametti, G., Brooks, N., Duce, R. A., Jickells, T. D., Kubilay, N., Prospero, J. M. and Tegen, I.: Atmospheric global dust cycle and iron inputs to the ocean, Global Biogeochem. Cy., 19, GB4025, https://doi.org/10.1029/2004GB002402, 2005. Mahowald, N. M., Sebastian, E., Luo, C. et al.: Atmospheric iron deposition: global distribution, variability, and human perturbations, Annu. Rev. Mar. Sci., 1, 245–278, 2009. Mamane, Y., Miller, J., and Dzubay, T.: Characterization of individual fly ash particles emitted from coal- and oil-fired power plants, Atmos. Environ., 20, 2125–2135, 1986. Mamuro, T., Mizohata, A., and Kubota, T.: Elemental composition of suspended particles released from various boilers, J. Jpn. Soc. Air Pollut., 14, 296–303, 1979a (in Japanese). Mamuro, T., Mizohata, A., and Kubota, T.: Elemental composition of suspended particles released in refuse incineration. J. Jpn. Soc. Air Pollut., 14, 190–196, 1979b (in Japanese). Mamuro, T., Mizohata, A., and Kubota, T.: Elemental composition of suspended particles released from iron and steel works, J. Jpn. Soc. Air Pollut., 15, 69–76, 1980 (in Japanese). Martin, J. H., Coale, K. H., Johnson, K. S. et al.: Testing the iron hypothesis in ecosystems of the equatorial Pacific Ocean, Nature, 371, 123–129, 1994. Maxwell-Meier, K., Weber, R., Song, C., Orsini, D., Ma, Y., Carmichael, G. R., and Streets, D. G.: Inorganic composition of fine particles in mixed mineral dust–pollution plumes observed from airborne measurements during ACE-Asia, J. Geophys. Res., 109, D19S07, https://doi.org/10.1029/2003JD004464, 2004. McNaughton, C. S., Clarke, A. D., Kapustin, V., Shinozuka, Y., Howell, S. G., Anderson, B. E., Winstead, E., Dibb, J., Scheuer, E., Cohen, R. C., Wooldridge, P., Perring, A., Huey, L. G., Kim, S., Jimenez, J. L., Dunlea, E. J., DeCarlo, P. F., Wennberg, P. O., Crounse, J. D., Weinheimer, A. J., and Flocke, F.: Observations of heterogeneous reactions between Asian pollution and mineral dust over the Eastern North Pacific during INTEX-B, Atmos. Chem. Phys., 9, 8283–8308, https://doi.org/10.5194/acp-9-8283-2009, 2009. Meng, Z., Seinfeld, J. H., Saxena, P., and Kim, Y. P.: Atmospheric gas aerosol equilibrium: IV. Thermodynamics of carbonates, Aerosol Sci. Technol., 23, 131–154, 1995. Meskhidze, N., Chameides, W. L., Nenes, A. and Chen, G.: Iron mobilization in mineral dust: Can anthropogenic SO<sub>2</sub> emissions affect ocean productivity?, Geophys. Res. Lett., 30(21), 2085, https://doi.org/10.1029/2003GL018035, 2003. Meskhidze, N., Chameides, W. L., and Nenes, A.: Dust and pollution: A recipe for enhanced ocean fertilization?, J. Geophys. Res., 110, D03301, https://doi.org/10.1029/2004JD005082, 2005. Mills, M. M., Ridame, C., Davey, M., La Roche, J., and Geider, R. J.: Iron and phosphorus co-limit nitrogen fixation in the eastern tropical north Atlantic, Nature, 429, 292–294, 2004. Nagy, K. L.: Dissolution and precipitation kinetics of sheet silicates, in Chemical Weathering Rates of Silicate Minerals, Rev. Mineral., vol. 31, 174–233, Mineral. Soc. of Am., Washington, DC, 1995. Nishikawa, M., Kanamori, S., Kanamori, N., and Mizoguchi, T.: Kosa aerosol as eolian carrier of anthropogenic material, Sci. Total Environ., 107, 13–27, 1991. Olmez, I., Sheffield, A., Gordon, G., Houck, J., Pritchett, L., Cooper, J., Dzubay, T. G., and Bennett, R.: Compositions of particles from selected sources in Philadelphia for receptor modeling applications, J. Air Pollut. Control Assoc., 38, 1392–1402, 1988. Paris, R., Desboeufs, K. V., Formenti, P., Nava, S., and Chou, C.: Chemical characterisation of iron in dust and biomass burning aerosols during AMMA-SOP0/DABEX: implication for iron solubility, Atmos. Chem. Phys., 10, 4273–4282, https://doi.org/10.5194/acp-10-4273-2010, 2010. Pokrovsky, O. S. and Schott, J.: Processes at the magnesium-bearing carbonates/solution interface. II. Kinetics and mechanism of magnesite, Geochim. Cosmochim. Acta, 63, 881–897, 1999. Rotman, D. A., Atherton, C. S., Bergmann, D. J., et al.: IMPACT, the LLNL 3-D global atmospheric chemical transport model for the combined troposphere and stratosphere: Model description and analysis of ozone and other trace gases, J. Geophys. Res., 109, D04303, https://doi.org/10.1029/2002JD003155, 2004. Schroth, A. W., Crusius, J., Sholkovitz, E. R., and Bostick, B. C.: Iron solubility driven by speciation in dust sources to the ocean, Nat. Geosci., 2, 337–340, https://doi.org/10.1038/ngeo501, 2009. Sedwick, P. N., Sholkovitz, E. R., and Church, T. M.: Impact of anthropogenic combustion emissions on the fractional solubility of aerosol iron: Evidence from the Sargasso Sea, Geochem. Geophys. Geosyst., 8, Q10Q06, https://doi.org/10.1029/2007GC001586, 2007. Shao, L. Y., Li, W. J., Yang, S. S., Shi, Z. B., and Lü, S. L.: Mineralogical characteristics of airborne particles collected in Beijing during a severe Asian dust storm period in spring 2002, Science in China(D), 50(6), 953–959, 2007. Shi, Z., Shao, L., Jones, T. P., and Lu, S.: Microscopy and mineralogy of airborne particles collected during severe dust storm episodes in Beijing, China, J. Geophys. Res., 110, D01303, https://doi.org/10.1029/2004JD005073, 2005. Shi, Z., Krom, M. D., Bonneville, S., Baker, A. R., Jickells, T. D., and Benning, L. G.: Formation of iron nanoparticles and increase in iron reactivity in mineral dust during simulated cloud processing, Environ. Sci. Technol., 43, 6592–6596, 2009. Sholkovitz, E. R., Sedwick, P. N., and Church, T. M.: Influence of anthropogenic combustion emissions on the deposition of soluble aerosol iron to the ocean: Empirical estimates for island sites in the North Atlantic, Geochim. Cosmochim. Acta, 73, 3981–4003, 2009. Siefert, R. L., Johansen, A. M., and Hoffmann, M. R.: Chemical characterization of ambient aerosol collected during the southwest monsoon and intermonsoon seasons over the Arabian Sea: Labile-Fe(II) and other trace metals, J. Geophys. Res., 104, 3511–3526, 1999. Skopp, J. M.: Physical properties of primary particles, in Handbook of Soil Science, edited by: Summer, M. E., 3–17, CRC Press, Boca Raton, Fla., 2000. Smith, R., Campbell, J., and Nielson, K.: Characterization and formation of submicron particles in coal-fired plants, Atmos. Environ., 13, 607–617, 1979. Solmon, F., Chuang, P. Y., Meskhidze, N., and Chen, Y.: Acidic processing of mineral dust iron by anthropogenic compounds over the North Pacific Ocean, J. Geophys. Res., 114, D02305, https://doi.org/10.1029/2008JD010417, 2009. Song, C. H. and Carmichael, G. R.: The aging process of naturally emitted aerosol (sea-salt and mineral aerosol) during long range transport, Atmos. Environ., 33(14), 2203–2218, 1999. Song, C. H. and Carmichael, G. R.: Gas-particle partitioning of nitric acid modulated by alkaline aerosol, J. Atmos. Chem., 40(1), 1–22, 2001. Streets, D. G., Bond, T. C., Carmichael G. R., et al.: An inventory of gaseous and primary aerosol emissions in Asia in the year 2000, J. Geophys. Res., 108(D21), 8809, https://doi.org/10.1029/2002JD003093, 2003. 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, 1213–1236, https://doi.org/10.5194/acp-7-1213-2007, 2007. Sun, J., Chang, M., and Liu, T.: Spatial and temporal characteristics of dust storms in China and its surrounding regions, 1960–1999: Relations to source area and climate, J. Geophys. Res., 106, 18331–18344, 2001. Tang, Y. H., Carmichael, G. R., Seinfeld, J. H., et al.: Three-dimensional simulations of inorganic aerosol distributions in east Asia during spring 2001, J. Geophys. Res., 109, D19S23, https://doi.org/10.1029/2003JD004201, 2004. Tessier, D.: Behavior and microstructure of clay minerals, in Soil Colloids and Their Associations in Aggregates, edited by: De Boodt, M. F., Hayes, M., and Herbillon, A., 347–415, Springer, New York, 1990. Turn, S. Q., Jenkins, B. M., Chow, J. C., Pritchett, L. C., Cambell, D., Cahill, }T.{, and Whalen{, }S. A.: Elemental characterization of particulate matter emitted from biomass burning: Wind tunnel derived source profiles for herbaceous and wood fuels, J. Geophys. Res., 102, 3683–3699{, }1997. Ward, D. E., Setzer, A. W., Kaufman, Y. J., and Rasmussen, R. A.: Characteristics of smoke emissions from biomass fires of the Amazon region – BASE-A experiment, in: Global Biomass Burning: Atmospheric, Climatic, and Biospheric Implications, edited by: Levine, J. S., 394–402, MIT Press, Cambridge, MA, 1991. Ward, D. E., Susott, R. A., Kauffman, J. B., Babbitt, R. E., Cummings, D. L., Dias, B., Holben, B. N., Kaufman, Y. J., Rasmussen, R. A., and Setzer, A. W.: Smoke and fire characteristics for cerrado and deforestation burns in Brazil: BASE-B experiment, J. Geophys. Res., 97, 14601–14619, 1992. Yamasoe, M. A., Artaxo, P., Miguel, A. H., and Allen, A. G.: Chemical composition of aerosol particles from direct emissions of vegetation fires in the Amazon Basin: Water-soluble species and trace elements, Atmos. Environ., 34, 1641–1653, 2000. Zhang, D., Shi, G.-Y., Iwasaka, Y., and Hu, M.: Mixture of sulfate and nitrate in coastal atmospheric aerosols: Individual particle studies in Qingdao (36°04´ N, 120°21´ E), China, Atmos. Environ., 34, 2669–2679, 2000. Zhu, X. R., Prospero, J. M., Millero, F. J., Savoie, D. L., and Brass, G. W.: The solubility of ferric ion in marine mineral aerosol solutions at ambient relative humidities, Mar. Chem., 38, 91–107, 1992. Zhuang, G., Yi, Z., Duce, R. A., and Brown, P. R.: Link between iron and sulphur cycles suggested by detection of Fe(II) in remote marine aerosols, Nature, 355, 537–539, 1992. Zinder, B., Furrer, G., and Stumm, W.: The coordination chemistry of weathering: II. Dissolution of Fe(III) oxides, Geochim. Cosmochim. Acta, 50(9), 1861–1869, 1986.