title: Size-dependent changes in sea spray aerosol composition and properties with different seawater conditions.
abstract: 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 in individual SSA 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 μm. 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 Mg(2+) 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 nm, 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.
authors: Department of Chemistry, University of Iowa , Iowa City, Iowa 52242, United States.
authors: Andrew P
authors: AP
authors: Ault
authors: Ryan C
authors: RC
authors: Moffet
authors: Jonas
authors: J
authors: Baltrusaitis
authors: Douglas B
authors: DB
authors: Collins
authors: Matthew J
authors: MJ
authors: Ruppel
authors: Luis A
authors: LA
authors: Cuadra-Rodriguez
authors: Defeng
authors: D
authors: Zhao
authors: Timothy L
authors: TL
authors: Guasco
authors: Carlena J
authors: CJ
authors: Ebben
authors: Franz M
authors: FM
authors: Geiger
authors: Timothy H
authors: TH
authors: Bertram
authors: Kimberly A
authors: KA
authors: Prather
authors: Vicki H
authors: VH
authors: Grassian
mesh_terms: D000336:Aerosols / Q000032:analysis* / Q000737:chemistry*; D001419:Bacteria; D003460:Crystallization; D017348:Microscopy, Electron, Scanning Transmission; D010316:Particle Size; D010839:Phytoplankton; D012623:Seawater / Q000737:chemistry* / Q000382:microbiology; D012965:Sodium Chloride / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy; D014965:X-Rays
chemical_list: D000336:Aerosols; D012965:Sodium Chloride