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.
