Chemical aging and the hydrophobic-to-hydrophilic conversion of carbonaceous aerosol

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Read Full Article (file size: 219237 bytes) Cited by GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L24806, doi:10.1029/2006GL027249, 2006 Chemical aging and the hydrophobic-to-hydrophilic conversion of carbonaceous aerosol Markus D. Petters Department of Atmospheric Science, Colorado State University, Ft. Collins, Colorado, USA Anthony J. Prenni Department of Atmospheric Science, Colorado State University, Ft. Collins, Colorado, USA Sonia M. Kreidenweis Department of Atmospheric Science, Colorado State University, Ft. Collins, Colorado, USA Paul J. DeMott Department of Atmospheric Science, Colorado State University, Ft. Collins, Colorado, USA Aiko Matsunaga Air Pollution Research Center, University of California, Riverside, California, USA Yong B. Lim Air Pollution Research Center, University of California, Riverside, California, USA Paul J. Ziemann Air Pollution Research Center, University of California, Riverside, California, USA Abstract Laboratory experiments simulating chemical aging of carbonaceous aerosol by atmospheric oxidants demonstrate that oxidative processing increases their ability to activate as cloud droplets. A microphysical model shows, however, that the measured increase in hygroscopicity is insufficient to lead to efficient wet scavenging for sub-100 nm particles that are typically emitted from combustion sources. The absence of an efficient atmospheric oxidation pathway for hydrophobic-to-hydrophilic conversion suggests that the fate of carbonaceous aerosol is instead controlled by its interaction with more hydrophilic species such as sulfates, nitrates, and secondary organic aerosol, leading to longer lifetimes, higher burdens, and greater contributions to climate forcing in the free troposphere than are currently estimated. Received 15 June 2006; accepted 7 November 2006; published 19 December 2006. Keywords: organic aerosol; cloud condensation nuclei; chemical aging. Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906); 0320 Atmospheric Composition and Structure: Cloud physics and chemistry; 0330 Atmospheric Composition and Structure: Geochemical cycles (1030). Read Full Article (file size: 219237 bytes) Cited by Citation: Petters, M. D., A. J. Prenni, S. M. Kreidenweis, P. J. DeMott, A. Matsunaga, Y. B. Lim, and P. J. Ziemann (2006), Chemical aging and the hydrophobic-to-hydrophilic conversion of carbonaceous aerosol, Geophys. Res. Lett., 33, L24806, doi:10.1029/2006GL027249. Copyright 2006 by the American Geophysical Union.

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