Size distributions of fine silicate and other particles in Masaya's volcanic plume
Size distributions of fine silicate and other particles in Masaya's volcanic plume
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DOI：
10.1029/2008jd011211
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发表时间：
2009-05
影响因子：
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通讯作者：
R. S. Martin;T. Mather;D. Pyle;M. Power;V. Tsanev;C. Oppenheimer;A. G. Allen;C. Horwell;E. P. Ward
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文献类型：
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作者：
R. S. Martin;T. Mather;D. Pyle;M. Power;V. Tsanev;C. Oppenheimer;A. G. Allen;C. Horwell;E. P. Ward
[1]在尼加拉瓜马萨亚火山火山口边缘进行了直接采样和遥感测量，以采样从活跃喷口喷出的气溶胶羽流。我们报告了通过粒子过滤器的自动扫描电子显微镜（QEMSCAN）分析，首次测量了Masaya羽流中精细硅酸盐颗粒（d < 10 μm）的尺寸分布。粒径分布近似对数正态分布，模态为d ~ 1.15 μm。这些粒子大多数是球形的。这些颗粒被解释为由飞溅过程产生的淬火岩浆的液滴。成分分析证实了先前的报告，即细硅酸盐颗粒显示出介于脱气岩浆和几乎纯二氧化硅之间的一系列成分，并且成分变化的程度随着颗粒尺寸的增加而减小。这些结果表明，细硅酸盐颗粒由于与羽流中的酸性液滴反应而发生改变。细硅酸盐颗粒的发射通量估计为~ 1011 s−1，相当于~ 55 kg d−1。利用太阳光度法、气溶胶光谱法和热降水法确定了羽流的总体粒径分布（0.01 < d(μm) < 10）。太阳光度测定和气溶胶光谱测定表明存在大量d ~ 1 μm的颗粒（假设为水性）。气溶胶光谱测量进一步显示，随着夜晚的临近，颗粒物的大小也在增加。Masaya的粒子发射通量估计为~ 1017 s−1，相当于在d < 4 μm时的~ 5.5 Mg d−1。
[1] 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 ∼ 1.15 μm. 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 reports 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 owing 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 nighttime 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.