Consumption of CH 3 Cl, CH 3 Br and CH 3 I and emission of CHCl 3 , CHBr 3 and CH 2 Br 2 from a retreating Arctic glacier's forefield

Abstract. The Arctic is one of the most rapidly warming regions of the Earth, with predicted temperature increases of 5–7 °C and the accompanying extensive retreat of Arctic glacial systems by 2100. This will reveal new proglacial land surfaces for microbial colonisation, ultimately succeeding to tundra over decades to centuries. An unexplored dimension to these changes is the impact upon the emission and consumption of halogenated organic compounds (halocarbons) from proglacial land surfaces. Halocarbons are involved in several important atmospheric processes, including ozone destruction, and despite considerable research, uncertainties remain in the natural cycles of some of these compounds. Using flux chambers, we measured halocarbon fluxes from proglacial land surfaces spanning recently-exposed sediments (