10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

Abstract View


Characterization of Surface-Active Organics in Seawater and Primary Marine Aerosol Particles

AMANDA FROSSARD, Tret Burdette, Whitney Hudson, University of Georgia

     Abstract Number: 924
     Working Group: Aerosol Chemistry

Abstract
Surface-active organics account for a minor fraction of the total organic carbon in the ocean but may have a major impact the surface tension of bursting bubbles at the sea surface that drive the production of primary marine aerosol particles (PMA). Surfactants associated with PMA may also significantly reduce the surface tension of water thereby increasing the potential for aerosol growth and cloud droplet activation. The transfer of surface-active organics from seawater and their relative enrichment in PMA remains unconstrained. In this study, PMA were produced from bursting bubbles in a high capacity marine aerosol generator. Generated PMA (gPMA) from ambient seawater and model seawater containing sea salt and surface-active organics were compared. The hygroscopic growth and number size distributions of the gPMA particles were measured using a Humidified Tandem Differential Mobility Analyzer (HTDMA). Surface-active organics were extracted from gPMA and seawater samples, and their compositions and concentrations were measured with mass spectrometry. Surface tensions and critical micelle concentrations (CMC) were quantified for the surfactant extracts, as well as the seawater. Higher surfactant concentrations were measured in gPMA from coastal and biologically productive seawater, compared to oligotrophic seawater. Surfactants extracted from coastal and biologically productive seawater directly were stronger than those from oligotrophic seawater. Photochemical reactions in the ocean mixed layer may influence surfactant properties and drive the observed variations in both seawater and gPMA surfactant concentrations over diel cycles. This work demonstrates a direct link between surfactants in seawater and those in PMA.