Size-resolved chemical composition of aerosol emitted by Erebus volcano, Antarctica

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Ilyinskaya, E, Oppenheimer, C, Mather, T, Martin, R, Kyle, P
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Antarctic; Austral; The Antarctic; Antarc*; Antarctica
• Online Access: https://doi.org/10.1029/2009GC002855; https://ora.ox.ac.uk/objects/uuid:fb875199-7d8a-4fb5-85da-32bdea009268

Persistent, open-vent degassing of Erebus volcano, Antarctica, is a significant point source of gases and aerosol to the austral polar troposphere. We report here on the chemical composition and size distribution of the Erebus aerosol, focusing on the water-soluble fraction. The aerosol was sampled at the rim of the active crater using a cascade impactor, which collected and sized particles in 14 size bins from >10 to 0.01 μm. The soluble fraction of the Erebus aerosol is distinct from other volcanic sources in several respects. It is dominated by chloride-bearing particles (over 30% of total mass) and has an unusually high Cl -/SO 4-2 molar ratio of 3.5. Coarse particles contribute little to the total mass of the soluble fraction. Elevated concentrations of F -, Cl -, Br -, and SO 4-2 are found in a narrow particle size fraction of 0.1-0.25 μm. The detection of particulate Br - reinforces our understanding of the potential for quiescent volcanic emissions to deplete tropospheric ozone. The small aerosol size reflects the low atmospheric temperature and humidity, which inhibit particle growth. Halide-alkali metal salts (Na, K)(Cl, F) appear to be the most abundant species in the aerosol. The concentration of Pb is high compared to other volcanoes; its exsolution may be promoted by the high abundance of halogens in Erebus magma. Despite the previously reported high NO x content in the plume, we did not detect significant quantities of nitrate in the near-vent aerosol. Our findings emphasize the potential regional significance of emissions from Erebus for understanding the Antarctic atmospheric composition and glaciochemical records. © 2010 by the American Geophysical Union.