Emission of Bromine and Iodine from Mt. Etna volcano

Constraining fluxes of volcanic bromine and iodine to the atmosphere is important given the significant role these species play in ozone depletion. However, very few such measurements have been made hitherto, such that global volcanic fluxes are poorly constrained. Here we extend the data set of volcanic Br and I degassing by reporting the first measurements of bromine and iodine emissions from Mount Etna. These data were obtained using filter packs and contemporaneous ultraviolet spectroscopic SO2 flux measurements, resulting in time-averaged emission rates of 0.7 kt yr(-1) and 0.01 kt yr(-1) for Br and I, respectively, from April to October 2004, from which we estimate global Br and I fluxes of order 13 (range, 3 - 40) and 0.11 (range, 0.04 - 6.6) kt yr(-1). Observed changes in plume composition highlight the coherent geochemical behavior of HCl, HF, HBr, and HI during magmatic degassing, and strong fractionation of these species with respect to SO