California Volcano Observatory

Gas Geochemistry Laboratory

Building 15, contact Sara Peek

Processing a volcanic gas sample

Lab manager Sara Peek processing a gas sample using the chromatograph

(Credit: Deborah Bergfeld, USGS. Public domain.)

The Volcano Hazards gas laboratory is optimized for chemical analysis of gas and liquid phases of volcanic and geothermal fluids. The lab utilizes two Varian gas chromatographs outfitted with thermal conductivity, flame ionization and pulsed discharge detectors using helium and argon carrier gases. Our methodology allows for analyses of volcanic and geothermal gases collected both in Giggenbach-type bottles containing sodium hydroxide or gases collected in dry evacuated bottles. The standard suite of gases determined includes Ar, CO, CH4, CO2, H2, H2S, He, N2, O2, SO2, and C2-C5 hydrocarbons, as well as isomers of butane and pentane (for geothermal studies).

Concentrations of condensed gases from the Giggenbach bottles are determined using ion chromatography (Dionex ICS-2000) for HCl, HF and H2S (after conversion to sulfate), ion selective electrode for NH3 and direct measurement of CO2 on a vacuum extraction line, following acidification of the NaOH solution.

Gas chromatograph

Gas chromatograph in the VSC Gas Laboratory

(Credit: Deborah Bergfeld, USGS. Public domain.)

Post-analysis processing of samples to isolate CO2 and CH4 gas for isotope analyses is performed on a standard vacuum line. The isotope analyses are performed at the Reston Stable Isotope Laboratory, in Reston Virginia.

The Volcano Hazards gas laboratory is organized under the California Volcano Observatory but the lab provides support for all 5 USGS volcano observatories, including the Alaska, Cascades, Hawaii and Yellowstone Volcano Observatories.