This project will focus on making and interpreting sensitive, high time resolution, in situ observations of acyl peroxy nitrates, an important class of organic nitrogen oxide reservoirs. Nitrogen oxides affect the abundance of ozone, which is a pollutant, a greenhouse gas, and a regulator of atmospheric oxidation. In this work, a custom-built chemical ionization mass spectrometer will be deployed in Blodgett Forest as part of a collaborative field campaign in a western Sierra Nevada ponderosa pine forest, to measure mixing ratios and fluxes of specific acyl peroxy nitrates. The abundance and partitioning of reactive nitrogen alters organic oxidation pathways and impacts secondary organic aerosol growth. The deposition of atmospheric nitrogen affects carbon storage in ecosystems, and therefore their response to increasing CO2 levels. Acyl peroxy nitrate deposition may represent an important ecosystem nitrogen source. Observations recently obtained with this instrument at a free tropospheric mountain observatory (Mt. Bachelor, Oregon) will also be analyzed to assess the importance of these nitrogen oxide reservoirs in pollution plumes transported from Asia to the northwestern United States. The overriding goal is to develop a detailed understanding of the fate of acyl peroxy nitrates in a range of environments and of the influence of local and regional processes on their global abundance. The broader scientific impact of this research will be an improved ability to predict future changes in air quality and climate, in which the chemistry of nitrogen oxides plays a fundamental role. Doctoral and undergraduate students will be trained in a range of analytical techniques and scientific analyses related to the field deployment of a state-of-the-art mass spectrometer and interpretation of the resulting data.
