Size-dependent changes in sea spray aerosol composition and properties with different seawater conditions

TitleSize-dependent changes in sea spray aerosol composition and properties with different seawater conditions
Publication TypeJournal Article
Year of Publication2013
AuthorsAult AP, Moffet RC, Baltrusaitis J, Collins DB, Ruppel MJ, Cuadra-Rodriguez LA, Zhao DF, Guasco TL, Ebben CJ, Geiger FM, Bertram TH, Prather KA, Grassian VH
JournalEnvironmental Science & Technology
Date Published2013/06
Type of ArticleArticle
ISBN Number0013-936X
Accession NumberWOS:000320097400014
Keywordsatmospheric particles; cloud condensation nuclei; coarse particulate matter; dissolved; electron-microscopy; ft-ir; marine aerosol; ocean; organic-matter; salt; sodium-chloride

A great deal of uncertainty exists regarding the chemical diversity of particles in sea spray aerosol (SSA), as well as the degree of mixing between inorganic and organic species individual SS particles. Therefore, in this study, single particle analysis was performed on SSA particles, integrating transmission electron microscopy with energy dispersive X-ray analysis and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy, with a focus on quantifying the relative fractions of different particle types from 30 nm to 1 mu m. SSA particles were produced from seawater in a unique ocean-atmosphere facility equipped with breaking waves. Changes to the SSA composition and properties after the addition of biological (bacteria and phytoplankton) and organic material (ZoBell growth media) were probed. Submicrometer SSA particles could be separated into two distinct populations: one with a characteristic sea salt core composed primarily of NaCl and an organic carbon and Mg2+ coating (SS-OC), and a second type consisting of organic carbon (OC) species which are more homogeneously mixed with cations and anions, but not chloride. SS-OC particles exhibit a wide range of sizes, compositions, morphologies, and distributions of elements within each particle. After addition of biological and organic material to the seawater, a change occurs in particle morphology and crystallization behavior associated with increasing organic content for SS-OC particles. The fraction of OC-type particles, which are mainly present below 180 mu, becomes dramatically enhanced with increased biological activity. These changes with size and seawater composition have important implications for atmospheric processes such as cloud droplet activation and heterogeneous reactivity.

Short TitleEnviron. Sci. Technol.