Aerosol phase transformation in the atmosphere
Ambient aerosols are frequently composed of hygroscopic inorganic salts such as chlorides, sulfates and nitrates in either pure or mixed forms. Such inorganic salt aerosols exhibit the properties of deliquescence and efflorescence in air. The phase transformation from a solid particle to a saline droplet usually occurs spontaneously when atmospheric relative humidity reaches a level specific to the chemical composition of the aerosol particle. Conversely, when relative humidity decreases and becomes low enough, a saline droplet will evaporate and suddenly crystallize, expelling all its water content. Information on the composition and temperature dependence of these properties is required in mathematical models for describing the dynamic and transport behavior of ambient aerosols. Experiments are carried out in the temperature range 5--35{degrees}C, using single particles individually suspended in an electrodynamic cell that can be evacuated and back filled with water vapor. The phase transformation of the aerosol particle is monitored by laser light scattering and the relative humidity at the transition point is determined by directly measuring the water vapor pressure in the cell. Results are obtained for particles containing either a single salt or a preselected mixture of NaCl, KCl, NaNO{sub 3}, Na{sub 2}SO{sub 4} and (NH{sub 4}){sub 2}SO{sub 4}, which are common constituents of ambient aerosols. A theoretical model on the composition and temperature dependence of the deliquescence properties is developed for single and two-salt aerosol systems.
- Research Organization:
- Brookhaven National Lab., Upton, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 10190915
- Report Number(s):
- BNL-47713; CONF-930133-4; ON: DE93001903
- Resource Relation:
- Conference: 73. American Meteorological Society (AMS) annual meeting,Anaheim, CA (United States),17-22 Jan 1993; Other Information: PBD: Sep 1992
- Country of Publication:
- United States
- Language:
- English
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