Measuring and Modeling Microbe-Enrichment in Bubbles Bursting at the Air-Sea Interface

Microbes, pathogens, and other solid particulates suspended in a liquid frequently attach to the interface of entrained air bubbles as they rise to the surface. When the bubbles eventually rupture at the ocean surface, these particulates can be ejected into the atmosphere as film or jet droplets, such as those linked to the respiratory irritation experienced by shoreline residents during red tide events. Previous studies have demonstrated that the particulate concentration in these aerosols can be significantly higher than in the original bulk liquid. However, the evolution from enriched film to enriched droplets is not entirely understood. Here we develop a physical model for the concentration enrichment by considering the roles of scavenging and bubble-film draining. In addition, we experimentally measure particulate concentration in the bubble film prior to rupture using high-speed microscopy. The observed concentrations are consistent with our developed model.