AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Size-Dependent Changes in Sea Spray Aerosol Composition and Properties with Different Seawater Conditions
ANDREW AULT, Ryan Moffet, Jonas Baltrusaitis, Douglas Collins, Matthew Ruppel, Luis Cuadra-Rodriguez, Defeng Zhao, Timothy Guasco, Carlena Ebben, Franz Geiger, Timothy Bertram, Kimberly Prather, Vicki Grassian, University of Iowa
Abstract Number: 79 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Single particle methods, including transmission electron microscopy with energy dispersive X-ray analysis, Raman microspectroscopy, and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy, were used for detailed characterization of sea spray aerosol (SSA) particles. SSA particles were produced from breaking waves generated from seawater in a sealed wave flume apparatus from seawater, and changes to the SSA after the addition of biological (bacteria and phytoplankton) and organic material (ZoBell growth media) were probed. SSA particles can be characterized within two distinct populations: one with a distinct sea salt core and organic matter coating (SS-OC), and a second consisting of organic species mixed with sulfate (OC) without core/shell morphology. 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. Functional group analysis of the organic component of SS-OC particles showed long chain aliphatic species, though different modes in the C-H stretching region were enhanced before and after addition of biological and organic material. The fraction of OC particle types, which are mainly present below 300 nm, are dramatically enhanced with increased biological activity. Changes in relative amounts of SS-OC and OC populations as a function of size and seawater chemistry, as well as the variability within SS-OC, have important atmospheric implications for cloud droplet activation and heterogeneous reactivity.