Quantifying Natural and Anthropogenic Influences on Nitrogen Oxides Emissions and Chemistry

This project is expected to lead to a better understanding of how atmospheric nitrogen oxides (NOx) oxidation chemistry is influenced by natural and human activities and what impact it will have on nitrogen biogeochemical cycling and climate. The project's findings will inform predictive models for NOx emissions and oxidation under changing climate conditions. The project has the following objectives: (1) Quantify the interplay of volcanic eruptions with oxidation chemistry and reactive nitrogen emissions; (2) Assess the influence of natural climate change, specifically the Little Ice Age, on atmospheric oxidation chemistry within the northern hemisphere mid-latitudes; (3) Examine the influence of human-induced activities on oxidation chemistry and reactive nitrogen emissions. The study will analyze nitrate preserved in an ice core in a mid-latitude glacier to provide a unique, long-term record of past mid-latitude atmospheric composition. The stable isotopes of nitrate, formed via NOx oxidation in the atmosphere, will be extracted from the Upper Fremont Glacier ice core to reconstruct changes in NOx oxidation chemistry and emission sources since circa 1700 A.D. By analyzing key stable isotopes of oxygen and nitrogen with approximately annual resolution, the first comprehensive, over 100-year record from a mid-latitude glacier in the contiguous U.S. will be produced. This project will support an early-career scientist and contribute to the training of a graduate student. The project team also will participate in the ACS Seed Program at the University of South Carolina, that provides science research experience to underprivileged high school students. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.