Currently, the atmospheric methane burden is rising rapidly, but the extentto which shifts in coal production contribute to this rise is not known.Coalbed methane emissions into the atmosphere are poorly characterised, andthis study provides representative C signatures of methane emissions from specific coalfields. Integrated methane emissions from both underground and opencast coal mines in the UK, Australia and Poland were sampled and isotopically characterised. Progression in coal rank and secondary biogenic production of methane due to incursion of water aresuggested as the processes affecting the isotopic composition of coal-derivedmethane. An averaged value of −65 ‰ has been assigned tobituminous coal exploited in open cast mines and of −55 ‰ in deepmines, whereas values of −40 and −30 ‰ can be allocated toanthracite opencast and deep mines respectively. However, the isotopicsignatures that are included in global atmospheric modelling of coalemissions should be region- or nation-specific, as greater detail is needed,given the wide global variation in coal type.
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