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34043 
Journal Article 
Sulfate and nitrate data from the California Aerosol Characterization Experiment (ACHEX) 
Appel, BR; Kothny, EL; Hoffer, EM; Hidy, GM; Wesolowski, JJ 
1978 
1 
Environmental Science & Technology
ISSN: 0013-936X
EISSN: 1520-5851 
HEEP/78/12451 
12 
4 
418-425 
Sulfate and nitrate data obtained in the summers of 1972 and 1973 with five fixed and one mobile sampling laboratory within California's South Coast Air Basin are presented. Included are 24-h average concentrations, diurnal variations, and size distributions obtained using a Lundgren cascade impactor. In addition, results for ammonia, ammonium, and other chemical species are given. Two-hour average concentrations of nitrate and sulfate up to 149 and 70 pg/m3, respectively, are observed. The mass median diameters for sulfate are 0.3-0.4 ym, and for nitrate 0.3-1.6 pm, the latter varying with locations in the Basin. Ratios of ionic constituents and ambient ammonia levels suggest that the sulfate and nitrate are present principally as ammonium salts. The data are consistent with mechanisms for sulfate and nitrate formation from SO2 and NO, involving photochemical oxidants, oxidation in water droplets, and for SOz, oxidation on carbon particles.