Posted by: magmatist | August 11, 2012

Mount Baker gas chemistry abstract compares collection methods

Smiley fumarole, 2011. WWU Geology student Lora Beatty uses the ‘vacuum flask’ method to sample fumarole gases. The titanium tube is in the fumarole vent. It is connected to the collection flask (left center, in a snow-filled plastic bag) by the tygon hose. The meter records fumarole temperatures.

Fumarole gas chemistry analyses from Baker, Hood, and Lassen have been obtained by two methods. The traditional ‘gas vacuum flask’ method has been used for decades, and annually in Baker’s Sherman Crater for the past few years. This method collects gas from discrete fumarole vents. The delicate glass flasks must then be backpacked out and sent off to Menlo Park California for chemical analysis.

The portable gas sniffer built by Peter Kelly (CVO). The sensor measures and records H2O, CO2, SO2, H2S, temperature, and pressure.
Photo by Peter Kelly.

A newer method uses a passive multi-gas ‘sniffer’ system, designed by Peter Kelly at the Cascade Volcano Observatory. This method uses a set of gas samplers with built-in analytic software, and is self-contained inside a  backpackable hard case. The experimental ‘sniffer’ has been deployed at Baker, Saint Helens, Hood and Lassen over the past year. It passively analyses gas concentrations from within fumarole plumes. At Sherman Crater, for instance, the portable analyzer was placed a few meters away from a cluster of many very dynamic fumaroles, and inevitably sampled gas from all of them, as well as ambient gas from more distant vents in the crater.

An abstract comparing the data obtained by the two methods has been submitted to the December annual meeting of the American Geophysical Union (AGU) in San Francisco.  The authors are Peter Kelly, Cynthia Werner, William Evans, and Stephen Ingebritsen, all of the US Geological Survey, and Dave Tucker (Western Washington University).

The abstract is posted at the top of the ‘abstracts’ page over on the main MBVRC data website: http://mbvrc.wwu.edu/abstracts/index.php

The comparison of gas concentrations collected by the two methods uses the ratio of CO2 to H2S concentrations- these are the principal gases after water vapor. The passive automatic sniffer obtained data readings comparable to the vacuum flask method. However, analysis of gas samples captured in the traditional method determines a variety of other fumarole gases, including He, H2, O2, Ar, N2, and CH4.

The 2010 Sherman Crater team, with the full range of MBVRC fundraiser shirts over the years. Left to right: K. Kemplin, D. McKeever, M. Park, D. Graber, D. Tucker, S. Linneman, C. Linneman.

Quite a number of volunteer mountaineers have helped gather this data at Baker over the past 5 years or so. Many thanks to all of you. Baker sampling, including use of the new ‘sniffer’, will continue for the foreseeable future.

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