Lake Spray Aerosol Emissions alter thermodynamic equilibrium in the Great Lakes

Abstract:

Recent studies suggest that lake spray aerosol (LSA) can play an important role in the Great Lakes region, yet its impacts on atmospheric chemistry are not fully understood. Laboratory and field observations indicate that lake spray emissions in the Great Lakes include primarily calcium carbonate, with lower concentrations of other inorganic ions, organic species, and biological material. We develop a new, wind-driven lake spray aerosol emissions parameterization that resolves both particle size and chemical composition, and investigate the impact of these emissions on regional chemistry in the Great Lakes region. We conduct two WRF-Chem simulations for November 2015, a time period with high winds over the lake surface generating high lake surface emissions. One simulation includes only anthropogenic from the National Emissions Inventory (NEI), and the second simulation includes both anthropogenic emissions plus the new lake particle emissions (NEI+Lake). Results show that LSA could change the amount and composition of aerosol particles and other gas-phase species over the Great Lakes and surrounding lands through altering aerosol phase chemical reactions. LSA particles emitted from the surface of the Great Lakes increase particulate NO₃^- by 52% over the Great Lakes and by 16 % over land due to heterogeneous reactions between CaCO₃ and HNO₃. The cations emitted from lake spray affect the thermodynamic equilibrium, reducing particulate NH₄⁺ by 49% over the Great Lakes and by 7% over the surrounding land. This also influences gas-phase species in the region, by decreasing nitric acid by up to 85% over lakes. Overall, these simulations suggest that understanding LSA and its impact on other air pollutants is important for determining health and climate effects in the Great Lakes region.