Size distributions of fine silicate and other particles in Masaya's volcanic plume

Martin, R. S. and Mather, T. A. and Pyle, D. M. and Power, M. and Tsanev, V. I. and Oppenheimer, C. and Allen, A. G. and Horwell, C. J. and Ward, E. P. W. (2009) Size distributions of fine silicate and other particles in Masaya's volcanic plume. Journal of Geophysical Research - Atmospheres, 114. D09217. ISSN 0148–0227 DOI 10.1029/2008JD011211

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Abstract

Direct sampling and remote sensing measurements were made at the crater rim of Masaya volcano (Nicaragua) to sample the aerosol plume emanating from the active vent. We report the first measurements of the size distribution of fine silicate particles (d < 10 μm) in Masaya's plume, by automated scanning electron microscopy (QEMSCAN) analysis of a particle filter. The particle size distribution was approximately lognormal with modal d ~ 1.15μm. The majority of these particles were found to be spherical. These particles are interpreted to be droplets of quenched magma produced by a spattering process. Compositional analyses confirm earlier studies that the fine silicate particles show a range of compositions between that of the degassing magma and nearly-pure silica, and that the extent of compositional variability decreases with increasing particle size. These results indicate that fine silicate particles are altered due to reactions with acidic droplets in the plume. The emission flux of fine silicate particles was estimated as ~1011 s-1, equivalent to ~55 kg d-1. Sun photometry, aerosol spectrometry and thermal precipitation were used to determine the overall particle size distribution of the plume (0.01 < d(μm) < 10). Sun photometry and aerosol spectrometry measurements indicate the presence of a large number of particles (assumed to be aqueous)with d ~ 1 μm. Aerosol spectrometry measurements further show an increase in particle size as the night-time approached. The emission flux of particles from Masaya was estimated as ~1017 s-1, equivalent to ~5.5 Mg d-1 where d < 4 μm.

Item Type: Article
Uncontrolled Keywords: 09AREP; IA58
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Journal of Geophysical Research - Atmospheres
Volume: 114
Page Range: D09217
Identification Number: 10.1029/2008JD011211
Depositing User: Sarah Humbert
Date Deposited: 30 Apr 2009 08:49
Last Modified: 23 Jul 2013 09:54
URI: http://eprints.esc.cam.ac.uk/id/eprint/918

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