Grant: Research Tools and Instruments - Category 1 (<$150,000)

Marine aerosols are poorly characterized and may have a significant impact on air quality in coastal regions, as well as climate. These aerosols are formed through wave action in the ocean, releasing chemicals into the atmosphere in the form of gases or particles. Many of these chemicals are organic molecules, some of biological origin. Organic compounds can be toxic, bioaccumulative, or change the properties of the particles, which can, in turn, impact climate and air quality. The mechanism by which the ocean releases chemicals into the atmosphere is not well understood. Aerosols are all microscopic, yet they vary greatly in size, over many orders of magnitude in diameter. The smallest particles are only a few nanometres in size, while the largest exceed ten micrometres. Particles of different sizes are formed through different mechanisms. Thus, if we can look at the chemical composition of marine aerosols of different sizes, we can learn about their formation mechanisms. In particular, over the ocean, the thin layer of organic grime on the surface (sea-surface microlayer) may contribute to the loading of organic compounds in the atmosphere. To study these processes, an instrument that can distinguish between different sizes of particles and that can be run autonomously is needed. The Micro-Orifice Uniform Deposit Impactor (MOUDI(TM)) satisfies these criteria. The second generation instrument, the NanoMOUDI-II can better look at ultrafine particles, which are critical to understanding particle formation. This sampler allows us to distinguish between gas-particle interactions and primary sea-surface emissions. Using a NanoMOUDI-II, we propose to simultaneously measure subsurface water, the sea-surface microlayer and size-resolved marine aerosols to better understand the relationship between the ocean and the atmosphere for organic compounds. Initially, we will examine these processes for organic nitrogen compounds and persistent perfluorinated acids. These results will help us to better appreciate the source and composition of marine aerosols, which impact two-thirds of the world's surface and the majority of the world's population that live in coastal regions.