Quantification of the Emission of Atmospheric Microplastics and Nanoplastics via Sea Spray

There is growing interest in the transfer of micro- andnanoplastics(MNP) to the atmosphere from the ocean via sea spray, and a limitednumber of studies have quantified this emission. This study addressesthe uncertainty surrounding existing global oceanic MNP emission estimatesby developing an experimentally based emission parametrization. Weconducted systematic laboratory experiments to understand the impactof MNP size, density, and concentration in water on their aerosolization.The results show that the MNP considered in this study, with a diameterof <= 10 mu m, can be emitted via bubble bursting, with theaerosolization increasing monotonically with an increase in the concentrationin water and decreasing with an increase in the particle size. Floatingpolyethylene MNP are observed to be less effectively aerosolized thanpolystyrene MNP dispersed in bulk water. Using the developed emissionparametrization, we estimate that the upper limit of yearly MNP oceanicemission is 50.7 (14.2-93.4) quadrillion (10(15))pieces year(-1) and 1.66 (0.72-4.13) t year(-1). The experimental measurements and ensuing parametrizationdeveloped in this study are a timely contribution to the atmosphericmicroplastic modeling community and will help in further constrainingthe oceanic source of atmospheric MNP and their potential climatic,environmental, and health implications.