Selectivity Across the Interface: A Test of Surface Activity in the Composition of Organic-Enriched Aerosols from Bubble Bursting.

Although theories have been developed that describe surface activity of organic molecules at the air-water interface, few studies have tested how surface activity impacts the selective transfer of molecules from solution phase into the aerosol phase during bubble bursting. The selective transfer of a series of organic compounds that differ in their solubility and surface activity from solution into the aerosol phase is quantified experimentally for the first time. Aerosol was produced from solutions containing salts and a series of linear carboxlyates (LCs) and dicarboxylates (LDCs) using a bubble bursting process. Surface activity of these molecules dominated the transport across the interface, with enrichment factors of the more surface-active C4-C8 LCs (55 ± 8) being greater than those of C4-C8 LDCs (5 ± 1). Trends in the estimated surface concentrations of LCs at the liquid-air interface agreed well with their relative concentrations in the aerosol phase. In addition, enrichment of LCs was followed by enrichment of calcium with respect to other inorganic cations and depletion of chloride and sulfate.