Atmospheric chemistry in volcanic plumes
Atmospheric chemistry in volcanic plumes
复制标题
火山羽流中的大气化学
DOI：
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发表时间：
2010
影响因子：
11.1
通讯作者：
R. von Glasow
中科院分区：
文献类型：
--
作者：
R. von Glasow
最近的现场观测表明，静止脱气火山的大气羽流在化学上非常活跃，这表明涉及卤素物种的化学循环和对气溶胶粒子的异质反应所起的作用，这是以前对这类火山羽流未曾探索过的。这些测量的关键特征可以通过数值模型来再现，如本研究中使用的模型。该模型显示，烟羽中的反应性溴水平持续较高，导致了广泛的臭氧破坏，这取决于烟羽的扩散，可以维持几天。火山柱中二氧化硫的浓度非常高，大大缩短了OH自由基的寿命，因此在火山柱中几乎不存在。这将意味着火山柱中甲烷的寿命延长，除非火山柱中的活性氯化学足够强，足以抵消OH化学的缺乏。除了这里介绍的模型研究所显示的对臭氧的破坏之外，溴化学的另一个影响是汞的氧化。这与火山与溴共同排放的汞有关，但也与本底大气汞有关。汞的快速氧化意味着汞在大气中的寿命大大缩短，因此火山汞对大气背景的贡献可能比之前认为的要小。然而，其影响，特别是沉积对健康和环境的影响，可能是实质性的，需要进一步研究，特别是现场测量来验证这一假说。
Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.
影响因子：
3.9
作者：
R. S. Martin;T. Roberts;T. Mather;D. Pyle
通讯作者：
R. S. Martin;T. Roberts;T. Mather;D. Pyle