Smith Lecture: Sea Spray Aerosol: Impacts of Chemical Composition on Climate-Relevant Properties in Marine Environments
Sea spray aerosol represents the largest flux particles to the atmosphere globally, yet uncertainties remain regarding their chemical composition and how this impacts the Earth’s climate. Using a unique, controlled ocean-atmosphere facility for sea spray aerosol generation, the physicochemical properties of nascent sea spray particles were measured using a combination of off-line microscopy and spectroscopy (TEM-EDX&EELS and Raman microspectroscopy) with on-line mass spectrometry (ATOFMS) on sea spray generated in an isolated setting where seawater chemistry could be systematically altered to study changes in the aerosols produced. The data show a range of particle types, morphologies and chemical composition. These same techniques were then used to probe changes in physicochemical properties of sea spray particles following heterogeneous chemical reactions with nitric acid (HNO3). Upon reaction with HNO3, these particles were observed to undergo a phase separation leading to a redistribution of cations, anions, and organic species that can alter trace gas uptake, mass transfer, and partitioning. These changes have important implications for the environmental and climate impacts of sea spray aerosol.