Halogens in the coastal snow pack near Barrow, Alaska: Evidence for active bromine air-snow chemistry during springtime

Abstract

We measured halide concentrations of snow and frost flowers in the vicinity of Barrow, Alaska. We find that the ratio of bromide to sodium in frost flowers is slightly enhanced (≈ 10%) as compared to sea water. In contrast, the ratio of bromide to sodium in some snow samples is more than an order of magnitude enhanced, and in other samples is more than an order of magnitude depleted. We interpret the bromide depleted snow as having been processed by heterogeneous chemistry and providing reactive halogen compounds to the atmosphere. The eventual end product of reactive bromine chemistry is HBr that is then deposited over a wide region, enhancing bromide in inland snow samples. Although frost flowers or open leads are likely to be the original source of halides that become reactive halogen gases, we find that the bromide release often occurs subsequent to production of aerosol from marine sources. Copyright 2005 by the American Geophysical Union.