CHEMICAL AND METEOROLOGICAL INFLUENCES ON SURFACE OZONE DESTRUCTION AT BARROW, ALASKA, DURING SPRING 1989

Surface ozone, particulate bromine and inorganic and organic gaseous b romine species were measured at Barrow, AK, during March and April 198 9 to examine the causes of surface ozone destruction during the arctic spring. Satellite images of the Alaskan Arctic taken during the same period were also studied in conjunction with calculated air mass traje ctories to Barrow to investigate the possible origins of the ozone-dep leted air. It was found that during major ozone depletion events (O-3 < 25 ppbv) concentrations of particulate bromine and the organic bromi nated gases bromoform and dibromochloromethane were elevated. Air mass trajectories indicated that the air had crossed areas of the Arctic O cean where leads had been observed by satellite. The transport time fr om the leads was typically a day or less, suggesting a fast loss mecha nism for ozone. A similarly fast production of particulate bromine was shown by irradiating ambient nighttime air in a chamber with actinic radiation that approximated daylight conditions. Such rapid reactions are not in keeping with gas-phase photolysis of bromoform, but further studies showed evidence for a substantial fraction of organic bromine in the particulate phase; thus heterogeneous reactions may be importa nt in ozone destruction.