Poster, Goldschmidt conference, Florence, Italy: 2013-09-01 - 2013-09-06
Abstract:
Determining volcanic gas composition by direct plume sampling is still challenge in volcanic research. At most volcanoes (e.g. Stromboli volcano, Italy) scientists have to deal with difficult access to the plume, strong atmospheric dilution and varying weather conditions making a high sampling performance necessary. Besides a more accurate quantification of the main acidic gas compounds (CO2, SO2, H2S, HCl) a reduction of detection limits for less abundant species (HF, HBr, HI) were achieved in this work. For this purpose a Raschig-Tube [1] was modified and utilized for the application on volcanic plumes. The theoretical and experimental absorption properties of the Raschig-Tube (RT) and the Drechsel bottle (DB) [2] set-ups were characterized and afterwards applied simultaneously to the well-established Filter packs technqiue (FP) in the field (on Stromboli and Mount Etna). The obtained results make a comparison between the set-ups possible and help to point out the potential weakness and strength of each set-up. Additionally, the analytical procedure, including sample preparation, analysis by Titration, Ion Chromatography and Inductively Coupled Plasma Mass Spectrometry, was optimised to accurately quantify molar concentrations of dissolved compounds. The progress in sampling and analysis led to a significant data set that covers most of the important elements. In particular, less abundant species were quantified more accurately due to the RT technqiue. Therefore, even iodine could be detected at Stromboli. Besides difficulties to determine fluorine and carbonate, influences of saturation effects on the FP results could be observed and characterized.