Research Objectives:
Despite decades of research, several important issues in antarctic atmospheric science are presently inadequately resolved, including quantifying the sources of nitrate aerosols over time. Today, little is known about past denitrification of the stratosphere in high-latitude regions. This lack of knowledge significantly limits our ability to understand the chemical state of ancient atmospheres and therefore evaluate present and past-coupled climate/atmosphere models. The role of nitrogen in environmental degradation is well known, and atmospheric aerosols have now been shown to have a mass-independent oxygen isotopic content.
We will therefore perform a detailed laboratory analysis of the mass-independent isotopic composition of processes associated with atmospheric nitrate trapped in the snow pack at the South Pole. Specifically, we will test whether the oxygen isotopes 16O, 17O, and 18O of nitrate can be used to probe the denitrification of the antarctic stratosphere.
We will also investigate the stable oxygen isotope ratios of nitrate collected both in real time and from the snow in Antarctica. Full-year nitrate aerosol collections, with resolution time horizons of a week, will be performed at the South Pole. Weekly aerosol collections will help us identify any seasonal trend in the oxygen-17 excess anomaly and eventually link it to the denitrification of the antarctic stratosphere.
In addition, we will use this data set to test our assumption that the oxygen isotopic anomaly of nitrate is mainly formed in the stratosphere and is well preserved in the snow pack. If this is true, we will for the first time resolve an atmospheric signal extracted from a nitrate profile. The snow pit will allow us to see any trend in the data over a time span of many decades.
