The flux of bromoform from the ice-covered ocean to the atmosphere has been determined for the first time. The rates are low in static flux chambers. The first time-series measurements of tropospheric ozone levels over sea ice in the Arctic are presented. Ozone concentrations over sea ice in spring have been observed to decline, sometimes to undetectable values, similar to previous terrestrial observations.

Examination of historical ozonesonde profile data collected by Environment Canada at Resolute Bay, NWT, Canada shows that ozone depletion is most pronounced and persistent in spring, but significant depletion may occur even during winter darkness when local photolysis would be negligible.