Salinity and Surfactant Effects on Bubble Bursting in Decaying Rafts

Breaking ocean waves generate rafts of bubbles on a large scale, which then burst and produce sea spray droplets which enter the atmosphere. These droplets carry with them aerosols and pollutants which affect the global environment. To understand how ocean conditions affect bursting and sea spray production, we study bubble rafts in artificial sea water with added surfactant. Rafts with standardized size distributions are generated by an impinging jet across varying salinity and humidity conditions. The decay of the rafts is observed synchronously with in-line holographic measurements of ejected droplets. We evaluate the statistical raft decay and drop production through size-dependent bursting and coalescence rates, and ejected droplet size distributions. We will discuss bubble lifetime and droplet production as a function of their sizes and the solution properties, i.e. salt and surfactant type and concentration.