Investigation of the multiple roles of tropospheric halogen chemistry during Arctic ozone depletion events

The involvement of halogen chemistry in the Arctic troposphere has been studied intensely following the discovery of the springtime depletion of ozone in the 1980s. It is understood that reactive halogen species, in particular bromine atoms, are responsible for the destruction of low-level ozone and gaseous elemental mercury and the oxidation of particular volatile organic compounds. Presented here are multiple methods for the investigation of the roles of halogen chemistry in the destruction of these species. This work describes the analysis of the vertical scale of halogen chemistry in the Arctic troposphere through the collection of vertical concentration profiles of hydrocarbons understood to play a prominent role in chemistry initiated by chlorine, in an effort to better understand the source region of the halogen precursors of this process. Additionally, described herein is a method developed for the more direct determination of halogen free radicals in the Arctic troposphere, based on chemical conversion of radical species to a more stable detected product. This method, among others, is used in a unique sea ice environment for the investigation of the initiation and progression of ozone depletion events in the Arctic troposphere