It is the purpose of this project to collect a year-long suite of air samples at Palmer Station to investigate the seasonal trend of the trace gas concentration. The samples will be analyzed at the Oregon Graduate Center for a number of trace components, especially chlorine and bromine containing species. These trace constituents have come from both biogenic and anthropogenic sources, and they have the capacity to alter the Earth's climate and to deplete the ozone layer in the way it has recently been depleted above Antarctica. This work is considered vital for a better understanding of the buildup of trace constituents, particularly those of high latitude marine origin. The proposers are leaders in this field, and the facilities are unique.