Articles | Volume 16, issue 21
https://doi.org/10.5194/acp-16-13669-2016
https://doi.org/10.5194/acp-16-13669-2016
Research article
 | 
03 Nov 2016
Research article |  | 03 Nov 2016

Carbon isotopic signature of coal-derived methane emissions to the atmosphere: from coalification to alteration

Giulia Zazzeri, Dave Lowry, Rebecca E. Fisher, James L. France, Mathias Lanoisellé, Bryce F. J. Kelly, Jaroslaw M. Necki, Charlotte P. Iverach, Elisa Ginty, Miroslaw Zimnoch, Alina Jasek, and Euan G. Nisbet

Abstract. Currently, the atmospheric methane burden is rising rapidly, but the extent to which shifts in coal production contribute to this rise is not known. Coalbed methane emissions into the atmosphere are poorly characterised, and this study provides representative δ13CCH4 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 are suggested as the processes affecting the isotopic composition of coal-derived methane. An averaged value of −65 ‰ has been assigned to bituminous coal exploited in open cast mines and of −55 ‰ in deep mines, whereas values of −40 and −30 ‰ can be allocated to anthracite opencast and deep mines respectively. However, the isotopic signatures that are included in global atmospheric modelling of coal emissions should be region- or nation-specific, as greater detail is needed, given the wide global variation in coal type.

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Short summary
Methane emissions estimates from the coal sector are highly uncertain. Precise δ13C isotopic signatures of methane sources can be used in atmospheric models for a methane budget assessment. Emissions from both underground and opencast coal mines in the UK, Australia and Poland were sampled and isotopically characterised using high-precision measurements of δ13C values. Representative isotopic signatures were provided, taking into account specific ranks of coal and mine type.
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