UC San Diego

Constraining air pollutant emissions is critical to assessing their impact on climate and public health and developing regulations to mitigate those effects. Despite all of the work done in atmospheric chemistry to date, there still exists significant uncertainties in emission inventories that can be addressed through direct measurement and study. While some emissions can be investigated with current instrumentation and technology, characterizing emissions in other areas is limited by the current sampling methods. This dissertation aims to contribute to advancing the current emissions inventories through both direct measurement and study of specific emission sources, as well as the development of novel instrumentation and technology to provide a solution to current sampling method needs.

The first section of this work focuses on investigating the emission of two specific organic acids from mobile sources. Emission of the potentially toxic trace gas isocyanic acid (HNCO) from light duty gasoline-powered vehicles (LDGVs) is investigated. The first real-time emission factor measurements for HNCO from a fleet of eight LDGVs are presented. In addition, this work also focuses on constraining the emissions factor of formic acid, one of the most abundant and ubiquitous organic acids in the atmosphere, for both LDGVs and ocean-going vessels. The second section of this dissertation assesses the impact of the Salton Sea, California’s largest body of water, on local and regional air quality. The impacts of the decrease in the size of the Salton Sea over the last 15 years and episodic, high-speed, sustained wind events at the Salton Sea are assessed. Finally, this work presents new advances in technology to close some of the current gaps in the existing sampling methods for aerosol measurement within the boundary layer. The novel implementation of a quadrotor unmanned aircraft system (UAS) drone and a custom sensor package is presented and utilized to generate vertical aerosol concentration profiles between 5 and 100 meters above sea level. The development of a novel small scale instrument for sizing and counting aerosol as small as 80 nm in diameter is also presented.