The Stratospheric Aerosol Layer and Anhydrous Reactions Between Ammonia and Sulfur Dioxide1

Abstract

Past studies of the reactions between anhydrous NH3 and anhydrous SO2 have suggested that two distinct products are formed. These products are stable below about 10C, are pale yellow or white solids, and have NH3:SO2 stoichiometric ratios of 1:1 and 2:1, respectively. The present work corroborates these results and presents quantitative measurements of the equilibrium total vapor pressure over the products at temperatures between −10 and −70C. Infrared spectra of the vapor infer that the products dissociate reversibly on sublimation into their components, NH3 and SO2. One white product was formed which exerted an extremely low vapor pressure at low temperatures. Regions of temperature minima would be preferred for its formation in the atmosphere. This stable product may appear at some stage in the formation of the ammonium sulfate layer in the lower stratosphere.

Nanometer-Sized Particle Formation from NH3/SO2/H2O/Air Mixtures by Ionizing Irradiation

“…2a and 5a suggested that material with vapor pressure lower than that of H2S04 is produced by H2S04-NH, reactions. Reactions that lead to particle formation in S02/H20/Air and NH,/S02/H20/Air mixtures have been discussed previously (Scott et al, 1969;Kiang et al, 1973;Hartley and Matteson, 1975;Tokunaga and Suzuki, 1984;Diamond et al, 1985;Jordan et al, 1986;Shen et al, 1990;Chang et al, 1992;Makel$ 1992;Christensen, 1994;Christensen et al, 1994). Eisele and Tanner (1991) and Christensen et al (1994) In the presence of NH,, H2S04 reacts with NH, to produce (NH4),SO,, Hartley and Matteson (1975), Shen et al (1990), and Christensen et al (1994) have reported that SO, also reacts directly with NH3, 7 SO, + NH, + NH3S03 It has been confirmed by X-ray diffraction analysis that NH3S0, is a solid at room temperature similar to (NH4),S04 (Hartley and Matteson, 1975).…”

Infrared Spectroscopic Study of Ammonia – Sulfur Dioxide – Water Solid State System

“…2), but the infrared spectra of these complexes have not been reported. Hata (3) had examined the infrared spectrum of the solid products formed by the reaction between anhydrous NH, and SO, but had detected only ammonium pyrosulfite containing traces of sulfite and bisulfite ions.…”

Meteorology of the upper atmosphere

“…Particulate matter in the stratosphere was investigated by means of twilight sky measurements [ Dave and Mateer, 1968;Volz, 1910a, b], optical radars [Pilipowskyj et al, Fiocco andGrams, 1969: Schuster, 1970], and direct sampling [Rosen, 1968]. Vapor pressure equilibrium between solid and gaseous phases in an ammonium sulfate system was suggested as a mecha nism responsible for formation of the stratospheric aerosol layer [Scott et al, 1969]. Newell [1970] suggested that the large increase in stratospheric aerosol content following the 1963 Mt.…”