Halogen and Sulfur Reactions Relevant to Polar Chemistry

It is widely hypothesized that catalytic cycles involving BrO_x species play an important role in the episodic destruction of ground-level ozone which is observed in the springtime Arctic boundary layer, although the exact mechanism for production of BrO_x radicals remains an open question [Barrie et al., 1988; Bottenheim et al., 1990; Finlayson-Pitts et al., 1990; McConnell et al., 1992]. The critical evidence linking ozone depletion with BrO_x chemistry is an observed negative correlation between ozone and filterable bromine [Bottenheim et al., 1990; Kieser et al., 1992]. In a recent field study of springtime Arctic boundary layer chemistry [Kieser et al., 1992], ozone concentrations and ethane concentrations were found to be correlated; this observation suggests that chlorine atoms (which react rapidly with ethane) may also be an important catalyst for ozone destruction under springtime Arctic conditions.