Efficient Sampling of Atmospheric Methane for Radiocarbon Analysis and Quantification of Fossil Methane.

Radiocarbon (C) measurements offer a unique investigative tool to study methane emissions by identifying fossil-fuel methane in air. Fossil-fuel methane is devoid of C and, when emitted to the atmosphere, causes a strong decrease in the ratio of radiocarbon to total carbon in methane (ΔCH). By observing the changes in ΔCH, the fossil fraction of methane emissions can be quantified.

Environmental baseline monitoring for shale gas development in the UK: Identification and geochemical characterisation of local source emissions of methane to atmosphere.

Baseline mobile surveys of methane sources using vehicle-mounted instruments have been performed in the Fylde and Ryedale regions of Northern England over the 2016-19 period around proposed unconventional (shale) gas extraction sites. The aim was to identify and characterise methane sources ahead of hydraulically fractured shale gas extraction in the area around drilling sites. This allows a potential additional source of emissions to atmosphere to be readily distinguished from adjacent sources, should gas production take place.

Detection of Fossil and Biogenic Methane at Regional Scales Using Atmospheric Radiocarbon.

Regional emissions of methane and their attribution to a variety of sources presently have large uncertainties. Measurements of radiocarbon (C) in methane (CH) may provide a method for identifying regional CH emissions from fossil versus biogenic sources because adding C-free fossil carbon reduces the C/C ratio (ΔCH) in atmospheric CH much more than biogenic carbon does. We describe an approach for estimating fossil and biogenic CH at regional scales using atmospheric ΔCH observations.

Evaluating methane inventories by isotopic analysis in the London region.

A thorough understanding of methane sources is necessary to accomplish methane reduction targets. Urban environments, where a large variety of methane sources coexist, are one of the most complex areas to investigate. Methane sources are characterised by specific δC-CH signatures, so high precision stable isotope analysis of atmospheric methane can be used to give a better understanding of urban sources and their partition in a source mix.

Marked long-term decline in ambient CO mixing ratio in SE England, 1997-2014: evidence of policy success in improving air quality.

Atmospheric CO at Egham in SE England has shown a marked and progressive decline since 1997, following adoption of strict controls on emissions. The Egham site is uniquely positioned to allow both assessment and comparison of 'clean Atlantic background' air and CO-enriched air downwind from the London conurbation. The decline is strongest (approximately 50 ppb per year) in the 1997-2003 period but continues post 2003.