Rising bubbles as mechanism for scavenging and aerosolization of diatoms

Abstract. Bubbles rising in clean saline water cause steady displacement of ions at the bubble boundaries that separate anions and cations based on ion mass. Anions of greater mass are resistant to displacement and concentrate on the bubble upper half sphere, while smaller and less massive cations are displaced towards lower pressure of the bottom half sphere. The separation into anionic and cationic domains on the bubble curvatures creates electric polarity that may draw particulates dispersed in the water. Viable diatoms as well as bacteria develop negative charge on outer membranes, that are attracted to the cationic bubble bottom half sphere and pocket. When bubble bursts at the air/water interface the diatoms and bacteria are ejected into the air with initial or secondary jet droplets that are projected upward with a small water column derived from a cationic vortex. Experiments conducted in brackish and oceanic saline water on Nanofrustulum and Cyclotella cells indicated that the averaged concentration in jet droplets compared to the original water volume (here termed the enrichment factor) for aerosolized diatoms may range from 8 to 307.