G03_P01

Source apportionment of fugitive methane emissions using radiocarbon in a Scottish river.

Gulliver P¹, Ascough P¹, Murray  C¹, Taylor C¹, Waldron S²

¹University Of Glasgow, East Kilbride, United Kingdom, ²University of Glasgow , Glasgow, United Kingdom

There is a long history of underground and open cast mining in Scotland. Closure of these mines results in local water table rebound as the mines slowly fill with water. This affects a number of Scottish river catchments and the escape of rebounding mine water provides a simple explanation for the presence of high methane concentrations in spring waters in such a catchment.

However, radiocarbon analysis of the dissolved methane in multiple springs of a Scottish catchment underlain by abandoned mine workings gave results of approximate 70 % modern, clearly showing that the methane is not solely geologically derived.

Radiocarbon analysis of the dissolved inorganic and organic carbon (DIC and DOC respectively) pools at the same sites showed that despite having lower % modern values then the dissolved methane, neither pool had a solely geological signature.

The source organic matter contributing to the majority of the dissolved methane and a significant proportion of the DIC and DOC comes from a much younger source and is biologically produced.