Constructing a 200,000-year Atmospheric N2O Record from the GISP II Ice Core

9321558 Sowers This award is for support for a study to construct a 200,000 year record of the concentration of nitrous oxide (N2O) in the atmosphere from the occluded air parcels in the Greenland Ice Sheet Project Two (GISP2) ice core. This record will provide information on nitrogen biogeochemical cycles over glacial/interglacial time periods. The concentration of nitrous oxide in air is determined by the sources and sinks of this gas on a global scale. Estimates of the sources (terrestrial and marine biospheres) and sinks (photodissociation in the stratosphere) are not presently well constrained but the terrestrial biosphere is thought to contribute about 80 % of the global nitrous oxide emissions with the other 20 % being made up from an oceanic contribution. Comparing an atmospheric nitrous oxide record with other bioactive gases such as carbon dioxide and methane will help in understanding the nature of changes in global carbon cycling throughout the past 200,000 years and will be a useful stratigraphic tool for correlating Greenland and Antarcitc ice cores. ***