Carbon dioxide emissions from fumarolic ice towers, Mount Erebus volcano, Antarctica

Abstract

AbstractDegassing at Mount Erebus occurs as a plume from a persistent convecting anorthoclase phonolite lava lake, and by flank degassing through warm ground and fumarolic ice towers within the summit caldera. The fumarolic ice towers offer a unique and simple approach to quantifying the flank CO2 emissions. Carbon dioxide effluxes were determined at openings in the ice towers by measuring the CO2 concentration, air-flow velocity, and size of the exit orifice. Fluxes ranged from <0.0001 to 0.034 kg s−1 at 43 actively degassing ice towers. Small patches of steaming warm ground contributed 0.010 kg s−1. The δ13C isotopic compositions of the CO2 samples ranged from −2.1 to −4.7‰, suggesting a magmatic origin for the CO2. Fumarolic ice towers allow diffuse degassing to be visually identified, providing a strong advantage in determining the total flux rate of these passive emissions. The estimated output of flank CO2 degassing is 0.46 kg s−1 (40 Mg d−1). Compared with direct airborne measurements of the volcanic plume, passive flank emissions constitute less than 2% of the total volcanic CO2 budget emitted from Mount Erebus.