The potential for methane emissions from groundwaters of the UK

Methane (CH4) is only a trace constituent of the atmosphere but an important greenhouse gas. Although groundwater is unlikely to be a major source of atmospheric CH4, its contribution to the CH4 budget of the UK has up to now been poorly characterised. Groundwater CH4 concentrations have been measured on 85 samples from water-supply boreholes and a further eight from other miscellaneous water sources. Concentrations in abstracted groundwaters ranged from <0.05 – 42.9 µg/l for Chalk, <0.05 – 22 µg/l for the Lower Greensand, 0.05 – 21.2 µg/l for the Lincolnshire Limestone and from