Rising bubbles as mechanism for scavenging and aerosolization of diatoms

Abstract

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.

The first characterization of airborne cyanobacteria and microalgae in the Adriatic Sea region

“…In addition, these organisms are lighter than e.g. diatoms, for which due to having heavy cell walls saturated with silica, wind speed will be of great importance [64]. As can be seen in this study, the amount of diatoms was relatively small.…”

Vertical transport of microplastics by rising bubbles

“…Rising bubbles in a water column can pick up particles in a process known as bubble scavenging [8][9][10][11][12]. Other works have already found that the microplastic concentration at the water surface is enriched [36][37][38], yet the mechanism for this enrichment is not identified.…”

Regional validation of the use of diatoms in ice cores from the Antarctic Peninsula as a Southern Hemisphere westerly wind proxy

“…3). Numerous studies have highlighted the relationship between wind strength and sea spray production (Blanchard, 1963;Schlichting, 1974;Monahan et al, 1983;Callaghan et al, 2008;Löndahl, 2014;Tesson et al, 2016;Wiśniewska et al, 2019;Marks et al, 2019). Stronger winds have been shown to enhance the production of sea spray aerosols, in-cluding microalgae, which implies an increased transfer of diatoms from the sea surface microlayer into the atmosphere (Marks et al, 2019).…”

“…Numerous studies have highlighted the relationship between wind strength and sea spray production (Blanchard, 1963;Schlichting, 1974;Monahan et al, 1983;Callaghan et al, 2008;Löndahl, 2014;Tesson et al, 2016;Wiśniewska et al, 2019;Marks et al, 2019). Stronger winds have been shown to enhance the production of sea spray aerosols, in-cluding microalgae, which implies an increased transfer of diatoms from the sea surface microlayer into the atmosphere (Marks et al, 2019). Studies on regional atmospheric circulation confirm that air masses from these regions are effectively transported to ice core sites Abram et al, 2010;Thomas and Bracegirdle, 2015;Allen et al, 2020), therefore establishing an efficient transport pathway from the identified source regions to the ice core sites.…”

“…Marine diatoms can be effectively lifted from the sea surface microlayer into the atmosphere by wind-induced bubble-bursting and wavebreaking processes (Cipriano and Blanchard, 1981;Farmer et al, 1993). Once in the atmosphere, they can be transported by winds over long distances (Chalmers et al, 1996;Elster et al, 2007;Harper and McKay, 2010;Budgeon et al, 2012;Marks et al, 2019;Allen et al, 2020). Diatom records have been evaluated at multiple ice core sites in the AP and Ellsworth Land (EL) regions (Tetzner et al, 2022a) to reveal consistent spatial variations and increases in the diatom concentration during the past 3 decades.…”