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Study on Chemical Monitoring of Volcanic gas using an IR spectroscopy

红外光谱法监测火山气体化学成分的研究

基本信息

批准号：
05453008
负责人：
NOTSU Kenji
金额：
$ 5.38万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05453008/
关键词：
Volcanic gas Monitoring Remote measurement Infrared absorption spectroscopy HC1 SO_2 Unzen volcano Vulcano volcano 空気酸化

项目摘要

1. I have developed a remote detection system of chemical components in volcanic gas, on the basis of infrared (IR) spectroscopy. The IR light which had passed through the volcanic gas was collected with a Cassegrainian telescope and was introduced into an FT-IR spectrometer.2. The measurements were carried out at Unzen, Kirishima, Aso, Sakurajima and Asama volcanoes, Japan, and also at Vulcano volcano, Itary.3. It is found that IR absorption spectra of chemical components were obtained, when IR source is naturally available behind the volcanic gas. In the case of Unzen volcano, absorption spectra of HC1 and SO2 were clearly identified using IR emission from hot lava dome behind the volcanic gas as an IR light source. This is first remote detection of HC1 in volcanic gas. In order to estimate the column amount of HC1 and SO2 from the observed spectra, a non-linear least-square method was applied, and then SO2/HC1 ratios of volcanic gas were calculated. The results shows that this remote monitoring technique is capable of detecting temporal change in the SO2/HCl ratios of volcanic gases emmitting far away from the observation site. In the case of Aso volcano, hot water standing on the bottom of the summit crater could be used as an IR light source, and absorption spectra of volcanic gas filling the crater were observed. At Vulcano volcano, Italy, the hot ground surface of the fumarolic area could be used as an IR light source, and spatial distribution in the SO2/HCl ratios of volcanic gas was detected.4. In general, chemical compositions of volcanic gas change after releasing into the atmosphere, bacause oxidations of the gas proceed in the atmosphere. The conversion of H2S to SO2 was experimentally checked. Therefore, it is suggested that SO2 detected in this remote monitoring includes original SO2 in the fumarole and SO2 derived from oxidation of H2S in the atmosphere.

1.我开发了一种基于红外光谱的火山气体化学成分远程探测系统。透过火山气体的红外光被卡塞格伦望远镜收集，并被引入FT-IR光谱仪。这些测量是在日本的云仙、雾岛、阿索、樱岛和浅间火山以及意大利的武尔卡诺火山进行的。研究发现，当火山气体背后有天然红外光源时，可以获得化学成分的红外吸收光谱。在云仙火山的情况下，使用来自火山气体后面的热熔岩圆顶的红外发射作为红外光源，可以清楚地识别HCl和SO2的吸收光谱。这是首次对火山气体中的HCl进行远程检测。为了从观测到的光谱中估计HCl和SO2的柱量，应用非线性最小二乘法，然后计算火山气体的SO2/HCl比。结果表明，这种远程监测技术是能够检测的时间变化的SO2/HCl比的火山气体排放远离观测点。在阿索火山的情况下，热水站在山顶火山口底部可以作为红外光源，并观察到火山气体填充火山口的吸收光谱。在意大利的Vulcano火山，火山区的热地表可以作为红外光源，探测火山气体中SO2/HCl比值的空间分布.一般来说，火山气体释放到大气中后，其化学成分会发生变化，因为气体在大气中会发生氧化。实验检查了H2S向SO2的转化。因此，建议在本次远程监测中检测到的SO2包括甲醇中的原始SO2和大气中H2S氧化产生的SO2。