%0 Generic
%A Bobrowski, Nicole
%D 2005
%F heidok:6052
%R 10.11588/heidok.00006052
%T Volcanic Gas Studies by Multi Axis Differential Absorption Spectroscopy
%U https://archiv.ub.uni-heidelberg.de/volltextserver/6052/
%X The chemistry of volcanic plumes can give insights into volcanic processes, which could help with improving the forecast of volcanic eruptions and is also of atmospheric relevance as the volcanic source of aerosols and trace gases can have a significant climatic impact. Although both are very important aspects, the chemical processes in volcanic plumes are inadequately understood. In this thesis, measurements by ground based Mini-MAX DOAS systems were carried out to study gas emissions from eight volcanoes. Bromine monoxide (BrO), chlorine monoxide (ClO), chlorine dioxide (OClO), formaldehyde (HCHO) and sulphur dioxide (SO2) abundances were measured. A global volcanic BrO flux of 1.2 - 13 Gg/y was determined. The study was focused on the measurements of BrO and SO2. The ratio between both trace gases was investigated at di®erent volcanic sites, as well as the dependence on the distance to the source and the volcanic activity. Additional attempts were made to distinguish the di®erent summit craters of Mt. Etna. No BrO was detected in proximity of the active vents of the volcanoes. An experimental study of the increase of the BrO/SO2 ratio with the aging plume was also conducted. ClO and OClO were measured in a volcanic plume for the first time. In contrast to BrO, ClO was detected near the volcanic source, and the distance dependency of ClO/SO2 ratio did not exhibit the increase found for the BrO/SO2 ratio. The miniaturized instrument developed in this thesis made possible to determine an SO2 flux (2.2 t/d) for the remote volcano Ollague. The length of the average light path through a volcanic plume and the problems of determining it was discussed. A comparison between an SO2 flux calculation assuming no scattering due to the volcanic plume and an SO2 flux estimating the enhancement of light path by scattering in the plume illustrate the present uncertainty.