Direct Observation of Heterogeneous Chemistry in the Atmosphere
Eric E. Gard,
Michael J. Kleeman,
Deborah
S. Gross,
Lara S. Hughes,
Jonathan O. Allen,
Bradley D. Morrical,
David P. Fergenson,
Tas Dienes,
Markus E.
Gälli,
Robert J. Johnson,
Glen R. Cass,
*
Kimberly A. Prather
*
The heterogeneous replacement of chloride by nitrate in individual
sea-salt particles was monitored continuously over time in the
troposphere with the use of aerosol time-of-flight mass spectrometry.
Modeling calculations show that the observed chloride displacement
process is consistent with a heterogeneous chemical reaction between
sea-salt particles and gas-phase nitric acid, leading to sodium nitrate
production in the particle phase accompanied by liberation of gaseous
HCl from the particles. Such single-particle measurements, combined
with a single-particle model, make it possible to monitor and explain
heterogeneous gas/particle chemistry as it occurs in the atmosphere.
E. E. Gard, D. S. Gross, B. D. Morrical, D. P. Fergenson, T. Dienes, M. E. Gälli, K. A. Prather,
Department of Chemistry, University of California, Riverside, CA 92521, USA.
M. J. Kleeman, L. S. Hughes, J. O. Allen, R. J. Johnson, G. R. Cass, Department of Environmental Engineering
Science, California Institute of Technology, Pasadena, CA 91125, USA.
*
To whom correspondence should be addressed. E-mail:
glen{at}eql.caltech.edu; prather{at}citrus.ucr.edu
