Sensing, Collection and Measurement
Volcanic gases were collected and analysed as long ago as 1790 by Scipione Breislak in Italy.
Volcanic gases can be sensed (measured in-situ) or sampled for further analysis. Volcanic gas sensing can be:
- within the gas by means of electrochemical sensors and flow-through infrared-spectroscopic gas cells
- outside the gas by ground-based or airborne remote spectroscopy (e.g., COSPEC, FLYSPEC, DOAS, FTIR)
Volcanic gas sampling is often done by a method involving an evacuated flask with caustic solution, first used by Robert W. Bunsen (1811-1899) and later refined by the German chemist Werner F. Giggenbach (1937-1997), dubbed Giggenbach-bottle. Other methods include collection in evacuated empty containers, in flow-through glass tubes, in gas wash bottles (cryogenic scrubbers), on impregnated filter packs and on solid adsorbent tubes.
Analytical techniques for gas samples comprise gas chromatography with thermal conductivity detection (TCD), flame ionization detection (FID) and mass spectrometry (GC-MS) for gases, and various wet chemical techniques for dissolved species (e.g., acidimetric titration for dissolved CO2, and ion chromatography for sulfate, chloride, fluoride). The trace metal, trace organic and isotopic composition is usually determined by different mass spectrometric methods.
Read more about this topic: Volcanic Gas
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