Atmospheric Particle Production from Freshwater and Oceanic Wave-breaking

Abstract

Wave-breaking in natural bodies of water forms bubbles that burst at the air-sea interface to produces atmospheric particles, known as sea spray aerosol (SSA) in marine environments and lake spray aerosol (LSA) in freshwater environments. While the properties and associated health and climate impacts of SSA have been widely reported, the impacts of SSA on atmospheric composition far from the ocean remain uncertain. In comparison, few studies of LSA exist. In this dissertation, the production and physiochemical properties of LSA and SSA at coastal and inland environments were examined. The results of this work increase our understanding of the atmospheric impacts of wave-breaking particle production from varied aquatic environments. In addition, this dissertation details efforts to integrate environmental chemistry research into introductory chemistry curricula to increase student engagement in the sciences. A laboratory-based LSA generator was constructed to produce and analyze particles from freshwater in a controlled environment for the first time. To evaluate the LSA generator, bubble and aerosol number size distributions were measured for salt solutions representative of freshwater and seawater, and a freshwater sample from Lake Michigan. The LSA generator was then utilized to produce particles from freshwater samples with varying blue green algae concentrations with analysis by single particle microscopy and mass spectrometry. Notably, the number fraction of LSA with organic carbon increased with decreasing diameters and the total number fraction of LSA with biological material increased directly with increased blue green algae concentration. During summertime ambient aerosol sampling conducted in northern Michigan, both SSA and LSA were observed by single particle microscopy and mass spectrometry. Air mass back trajectory analysis indicated that SSA originated from Hudson Bay, Canada and LSA originated from the Great Lakes, >700 km and >25 km from the sampling site, respectively. These results represent the furthest inland quantification of SSA particle mass contributions by single particle analysis and the first confirmation of the inland transport of LSA. Rapid sea ice loss is dramatically changing the Arctic surface, with increasing SSA production expected from newly exposed ocean surface. Multi-year bulk atmospheric particle inorganic ion concentrations, local sea ice conditions, and meteorology at Utqiaġvik, AK were combined to investigate the dependence of SSA mass concentrations on Arctic sea ice coverage and wind speed. Supermicron (1–10 μm) SSA mass concentrations increased in the presence of nearby leads (fractures in the sea ice) and wind speeds greater than 4 m s-1. SSA produced from leads has the potential to alter the chemical composition of the Arctic atmosphere and snowpack. To investigate impacts of SSA production from Arctic sea ice leads on snow chemistry, a course based undergraduate research experience (CURE) centered on Arctic snow chemistry was implemented in an existing introductory general chemistry laboratory course. Survey evaluation results indicate students in the snow chemistry CURE experienced greater gains in confidence of research skills and general attitudes towards chemistry compared to a traditional course. To increase the accessibility of the environmental chemistry CURE, a research-based laboratory experiment for the determination of chloride content in snow and other environmental samples with basic laboratory equipment was designed for the high school classroom. The positive impacts on undergraduates of the snow chemistry CURE, and the potential for its translation into the high school classroom, motivates further incorporation of environmental research experiences at an early academic career stage.