SO2 sequestration in large volcanic eruptions: High-temperature scavenging by tephra
SO2 sequestration in large volcanic eruptions: High-temperature scavenging by tephra
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DOI：
10.1016/j.gca.2013.02.018
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发表时间：
2013-06-01
影响因子：
5
通讯作者：
Delmelle, P.
中科院分区：
文献类型：
--
作者：
Ayris, P. M.;Lee, A. F.;Delmelle, P.
人们普遍认为，大规模火山爆发对气候的影响是由于岩浆排放的SO2在大气中转化为H2SO 4气溶胶后太阳辐射减少所致。因此，了解喷发羽流中SO2的命运对于更好地评估火山对气候的作用力至关重要。在这里，我们专注于火山灰的潜力，相互作用，并从喷发羽流中去除二氧化硫气体。火山灰对SO2的清除通常被认为是由H2SO 4冷凝物和火山灰颗粒之间的羽流低温反应驱动的。然而，在H2SO 4的露点温度（190-200摄氏度）以上，SO2气体-火山灰相互作用的重要性从未受到限制。在这里，我们报告了一项实验研究的结果，其中具有代表性的火山成分的硅酸盐玻璃暴露于25-800摄氏度的温度范围内的二氧化硫。我们发现，在600摄氏度以上，吸收的SO2玻璃表现出最佳的效率和安置surfectCaSO 4存款。该反应通过Ca 2+从玻璃颗粒的本体扩散到表面来维持。在800 ℃时，玻璃中Ca 2+的扩散系数在10（-13）-10（-14）cm（2）s（-1）范围内。我们认为，高温SO2清除富含玻璃火山灰收益由相同的Ca 2+扩散驱动的机制。使用一个简单的数学模型，我们估计SO2清除效率在800摄氏度的变化，
It is well accepted that the climate impact of large explosive volcanic eruptions results from reduction of solar radiation following atmospheric conversion of magmatic SO2 emissions into H2SO4 aerosols. Thus, understanding the fate of SO2 in the eruption plume is crucial for better assessing volcanic forcing of climate. Here we focus on the potential of tephra to interact with and remove SO2 gas from the eruptive plume. Scavenging of SO2 by tephra is generally assumed to be driven by in-plume, low-temperature reactions between H2SO4 condensates and tephra particles. However, the importance of SO2 gas-tephra interaction above the dew point temperature of H2SO4 (190-200 degrees C) has never been constrained. Here we report the results of an experimental study where silicate glasses with representative volcanic compositions were exposed to SO2 in the temperature range 25-800 degrees C. We show that above 600 degrees C, the uptake of SO2 on glass exhibits optimal efficiency and emplaces surficial CaSO4 deposits. This reaction is sustained via Ca2+ diffusion from the bulk to the surface of the glass particles. At 800 degrees C, the diffusion coefficient for Ca2+ in the glasses was in the range 10(-13)-10(-14) cm(2) s(-1). We suggest that high temperature SO2 scavenging by glass-rich tephra proceeds by the same Ca2+ diffusion-driven mechanism. Using a simple mathematical model, we estimated SO2 scavenging efficiencies at 800 degrees C varying from