Study of formation of coarse particle nitrate aerosol

• Published in: Atmospheric environment (1994) Vol. 30; no. 14; pp. 2475 - 2482
• Main Author: Pakkanen, Tuomo A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1996; Elsevier Science
• Subjects: Brackish; Earth, ocean, space; Exact sciences and technology; External geophysics; Freshwater; Ions; Marine; Meteorology; Nitrates; Nitric acid; Particles and aerosols; Q1; Salts; Europe; Finland; Finland, Helsinki; soil particles; Impactor; coarse particles; ions; nitrate; sea salt; size distribution; Particle size; Sea salt; Aerosols; Nitrates; Concentration; Dimension spectrum; Formation; Coarse particle
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/1352-2310(95)00492-0

The results of analyses of six atmospheric aerosol samples collected in Helsinki, Finland, using a Berner low-pressure impactor, are reported. Formation of coarse particle nitrate was studied by evaluating various ion balances of the measured water-soluble ions (NH 4 +, Na +, K +, Mg 2+, Ca 2+, Cl −, NO 3 − and SO 4 2−) and mass size distributions of Na + Ca 2+, Cl − and NO − 3. Atmospheric coarse particle NO − 3 was found to be formed in the reaction of nitric acid with sea- and soil-derived coarse particles. The fraction of nitrate found on sea and soil particles followed the measured concentrations and size distributions of these two particle types: the concentration ratio of soil to sea particles increased with increasing particle size as did the fraction of nitrate on soil particles. The reaction with sea-salt particles resulted in the evaporation of Cl − as HCI. The presence of non-sea-salt SO 4 2− indicates that also H 2SO 4 and/or SO 2 reacted with sea salt and contributed to the Cl − loss. Overall, the percentage of evaporated Cl − decreased with increasing particle size, which suggests a surface reaction mechanism. Cl − evaporation was almost complete for the 1–2 um diameter size fraction indicating that all major sea-derived chlorides, NaCl, MgCl 2, CaCl 2 and KCI, may react with acidic species in the atmosphere. The results showed further some indications of possible reaction of HCI with soil particles.