Journal of Geophysical Research: Atmospheres

Cover image for Vol. 122 Issue 22

Impact Factor: 3.454

ISI Journal Citation Reports © Ranking: 2016: 20/85 (Meteorology & Atmospheric Sciences)

Online ISSN: 2169-8996

Associated Title(s): Journal of Geophysical Research

Sea salt particles react with organic acids in atmosphere

Sea salt (sodium chloride, NaCl) particles lofted into the atmosphere by the motion of waves affect atmospheric chemistry; they can undergo reactions with trace atmospheric gases and internal mixing with anthropogenic pollutants depositing on particle surface. Several studies have found sea salt (sodium chloride, NaCl) particles in the atmosphere depleted in chloride and have attributed this to reactions with inorganic acids. However, reactions with inorganic acids do not fully account for the observed chloride depletion in some locations; it has been suggested that organic acids, likely of anthropogenic origin, may also play a role in chloride depletion, but results have been uncertain. To address the issue, Laskin et al. (2012) conducted a chemical imaging analysis of airborne particles collected on board aircraft during a flight in California's Central Valley in 2010. They found sea salt mixed with organic matter particles were depleted in chloride, suggesting that sea salt has reacted with anthropogenic organic acids, releasing volatile hydrogen chloride (HCl) into the atmosphere and leaving behind chloride-depleted sea salt particles. Corroborating the field evidence, the authors conducted systematic laboratory studies in which NaCl particles reacted with organic acids, resulting in chloride depletion and formation of organic salts. The authors conclude that these reactions, which are unique for aerosolized particles, were previously overlooked, and now they should be included in atmospheric chemistry models.

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