HR: 16:15h
AN: A54B-02    [Abstracts]
TI: Deliquescence and Crystallization of Ammonium Sulfate Particles Internally Mixed With Water-Soluble Organic Compounds
AU: * Parsons, M T
EM: matt@chem.ubc.ca
AF: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AU: Knopf, D A
EM: knopf@chem.ubc.ca
AF: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AU: Bertram, A K
EM: bertram@chem.ubc.ca
AF: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1 Canada
AB: Deliquescence and crystallization relative humidities of particles containing ammonium sulfate internally mixed with water-soluble organic material have been measured. The organic material included malonic acid, glycerol, levoglucosan, and Suwannee River fulvic acid. Results for deliquescence of systems with malonic and fulvic acids are in agreement with existing literature values. The glycerol system undergoes deliquescence at slightly lower relative humidity than previous measurements. The levoglucosan results are the first of this kind. Deliquescence relative humidities for the different systems are the same within the uncertainty of the measurements when the organic mole fraction is less than 0.35. The maximum deviation of deliquescence relative humidities across the systems is approximately 10 % relative humidity at an organic mole fraction of 0.6. The crystallization relative humidity (CRH) of ammonium sulfate with malonic acid, glycerol, or levoglucosan, decreases significantly from the CRH of pure ammonium sulfate when the organic mole fraction is greater than 0.25. This is in contrast to our previous study with glutaric acid where the CRH remained close to the CRH of pure ammonium sulfate up to a glutaric acid mole fraction of 0.4. In terms of atmospheric implications, we estimate that organics, on average, are only a minor perturbation on the deliquescence relative humidity of the pure inorganic particles; however, the organics, on average, may decrease the CRH of pure inorganic particles significantly and this effect depends on the type of organic material.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting