Effects of particulate properties on splash activity and particulate destination for particle-laden drop impacts on liquid pools

Abstract Contaminants such as microplastics, ash, and pollen are constantly carried between the ocean and atmosphere via raindrops, splash droplets, and breaking waves. These contaminants have an impact on marine life via bioaccumulation and alter the chemistry of the ocean, consequently impacting our weather prediction and radar systems. However, there are few studies involving deep pool drop impacts and even fewer where the impacting drop contains particulates, which would simulate the phenomena that naturally occur in our environment. For our study, we created a simplified system to mimic pollutant-laden raindrops impacting the ocean. Utilizing high-speed imaging, we characterized the effects of particle size, particle density, and seeding density on the splash phenomena and final particulate distribution. It was found that, while the particle properties (size, density, seeding density) did not alter the overall splash regimes, they did influence the dimensions of various characteristic splash morphologies, albeit to a much lesser extent than the impact energy of the droplet. We also identified relationships between the particle properties and the particulate distribution. Particle size and density have opposite effects on the percent of particulates in the bulk of the pool and on the surface. Seeding density has a significant influence only when there are no splash droplets. The percentage of particulates re-entering the atmosphere via splash droplets, on the other hand, are significantly affected by the particle properties; however, the exact effect is not yet clear. Understanding the particulate-ocean–atmosphere interactions allows us to improve our predictive system and ocean-simulating models.