The transformation of NOx (NO + NO2) into HNO3 is a fundamental process in tropospheric chemistry, yet the mechanisms of transformation are still not completely understood. This process is not only important for atmospheric chemistry but also for biogeochemical cycling as HNO3 is a major source of acid rain and bio-available fixed nitrogen. Multiple stable isotopes in nitrate, in particular mass independent isotope compositions, can be used to trace nitrogen oxidation processes in the atmosphere and they can be used to track the fate of acid rain and nitrogen deposition in biogeochemical systems. Nitrate contained in ice and the geologic record can then be used to assess linkages between atmospheric chemistry and climate variability and possible used to investigate past atmospheric chemistry on other planets, such as Mars. Finally stable isotope approaches can be used to examine biosphere turnover of nitrogen and its importance in water quality and eutrophication in aquatic ecosystems. This powerful new tool can be used in atmospheric chemistry, hydrology, geology, ecology and forensics.
Greg Michalski is an Assistant Professor at Purdue University in the Departments of Earth and Atmospheric Sciences and Chemistry. His research utilizes multiple isotopes, including mass independent isotope compositions, to understand the nitrogen cycle from local to regional to global scales. His field research includes work in the Atacama (Chile) and Kumtag (western China) Deserts and collaborative efforts with the National Atmospheric Deposition Program. Dr. Michalski joined Purdue University in 2005 after obtaining his M.A. (Environmental Chemistry), M.S. (Chemistry) and PhD. (Physical Chemistry) at the University of California, San Diego.