Bubble Extraction of Dissolved Gases from Groundwater Samples

Author: Walsh K.P.  

Publisher: Springer Publishing Company

ISSN: 0049-6979

Source: Water, Air, and Soil Pollution, Vol.115, Iss.1-4, 1999-10, pp. : 525-534

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Abstract

A technique is described for measuring the concentration of dissolved methane in water samples. A 250 L bubble is injected into a 5 mL vial to create a headspace. The headspace gas is subsequently analysed by gas chromatograph. The technique requires a headspace equilibrium time of at least 13 hours. The extraction efficiency of the method for methane saturated water was 101.9% ± 1%. The technique is applicable to other dissolved gases in groundwater. The method was used during a comparative evaluation of groundwater sampling devices at a field site. It was found that low flow rate sampling with either a Grundfos electric submersible pump or a peristaltic pump were more precise than using a bailer to measure dissolved methane.