High-temperature mixtures of magmatic and atmospheric gases

Martin, R. S. and Mather, T. A. and Pyle, D. M. (2006) High-temperature mixtures of magmatic and atmospheric gases. Geochemistry Geophysics Geosystems, 7. Q04006. DOI https://doi.org/10.1029/2005GC001186.

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Abstract

Recent measurements of BrO, NOx, and near-source sulfate in volcanic plumes suggest that volcanic vents might not simply act as point sources of emissions into the troposphere, but may also act as high-temperature reaction sites where mixtures of magmatic and ambient atmospheric gases may combine, giving new and previously unexpected reaction products. The detection of such species demands that a more complex model be developed for the interaction of volcanoes and atmospheres. We show that general thermodynamic models can be applied successfully to volcanic gas equilibria by comparing the results from HSC Chemistry with those from two volcanic gas equilibrium models (Solvgas and Gasmix). Using a thermodynamic model optimized for volcanic gas chemistry (C-O-S-H-F-Cl-Br-I-N-Ar speciation), we show that the volume ratio of atmospheric gas to magmatic gas in a high-temperature mixture is an important parameter of the volcanic plume chemistry, and our results suggest that even small amounts of air (a few % for an H2O-rich magmatic gas) in the high-temperature mixture are sufficient to yield elevated levels of reactive nitrogen, halogen (Cl, Br, and I), and sulfur species within the volcanic plume. Further modifications of the plume chemistry may also occur due to low-temperature reactions, and chemical schemes for the modification of halogen (Cl, Br, I), nitrogen, and sulfur chemistry are suggested, within the constraints imposed by recent measurements.

Item Type:	Article
Uncontrolled Keywords:	2006 AREP 2006 P IA51
Subjects:	05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions:	05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title:	Geochemistry Geophysics Geosystems
Volume:	7
Page Range:	Q04006
Identification Number:	https://doi.org/10.1029/2005GC001186.
Depositing User:	Sarah Humbert
Date Deposited:	16 Feb 2009 13:03
Last Modified:	23 Jul 2013 10:07
URI:	http://eprints.esc.cam.ac.uk/id/eprint/510

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