Radiocarbon dating of methane and carbon dioxide evaded from a temperate peatland stream
Streams draining peatlands export large quantities of carbon in different chemical forms and are an important part of the carbon cycle. Radiocarbon (14C) analysis/dating provides unique information on the source and rate that carbon is cycled through ecosystems, as has recently been demonstrated at the air–water interface through analysis of carbon dioxide (CO2) lost from peatland streams by evasion (degassing). Peatland streams also have the potential to release large amounts of methane (CH4) and, though 14C analysis of CH4 emitted by ebullition (bubbling) has been previously reported, diffusive emissions have not. We describe methods that enable the 14C analysis of CH4 evaded from peatland streams. Using these methods, we investigated the 14C age and stable carbon isotope composition of both CH4 and CO2 evaded from a small peatland stream draining a temperate raised mire. Methane was aged between 1617 and 1987 years BP, and was much older than CO2 which had an age range of 303–521 years BP. Isotope mass balance modelling of the results indicated that the CO2 and CH4 evaded from the stream were derived from different source areas, with most evaded CO2 originating from younger layers located nearer the peat surface compared to CH4. The study demonstrates the insight that can be gained into peatland carbon cycling from a methodological development which enables dual isotope (14C and 13C) analysis of both CH4 and CO2 collected at the same time and in the same way.
KeywordsRadiocarbon Methane Carbon dioxide Peatland Evasion
We thank staff at the NERC Radiocarbon Facility and SUERC AMS Facility. We are grateful to NERC for funding radiocarbon analyses, and to John Hawell and South Lanarkshire District Council for permission to use the study site.
- Billett MF, Harvey FH (In press) Measurements of CO2 and CH4 evasion from UK peatland headwater streams. Biogeochemistry. doi: 10.1007/s10533-012-9798-9
- Billett MF, Garnett MH, Hardie SML (2006) A direct method to measure 14CO2 lost by evasion from surface waters. Radiocarbon 48(1):61–68Google Scholar
- Billett MF, Garnett MH, Dinsmore KJ, Dyson KE, Harvey F, Thomson AM, Piirainen S, Kortelainen P (In press) Age and source of different forms of carbon released from boreal peatland streams during spring snowmelt in E. Finland. Biogeochemistry. doi: 10.1007/s10533-011-9645-4
- Chanton J, Glaser PH, Chasar L, Burdige D, Hines M, Siegel DI, Tremblay L, Cooper W (2008) Radiocarbon evidence for the importance of surface vegetation on fermentation and methanogenesis in contrasting types of boreal peatlands. Glob Biogeochem Cycl 22:GB4022. doi: 10.1029/2008GB003274 CrossRefGoogle Scholar
- Garnett MH, Hardie SML, Murray C (2011) Radiocarbon and stable carbon analysis of dissolved methane and carbon dioxide from the profile of a raised peat bog. Radiocarbon 53(1):71–83Google Scholar
- Hemming D, Yakir D, Ambus P, Aurela M, Besson C, Black K, Buchmann N, Burlett R, Cescatti A, Clement R, Gross P, Granier A, Grunwald T, Havrankova K, Janous D, Janssens IA, Knohl A, Ostner BK, Kowalski A, Laurila T, Mata C, Marcolla B, Matteucci G, Moncrieff J, Moors EJ, Osborne B, Pereira JS, Pihlatie M, Pilegaard K, Ponti F, Rosova Z, Rossi F, Scartazza A, Vesala T (2005) Pan-European delta C-13 values of air and organic matter from forest ecosystems. Glob Change Biol 11(7):1065–1093CrossRefGoogle Scholar
- Hornibrook ERC (2009) The stable carbon isotope composition of methane produced and emitted from northern peatlands. In: Baird A, Belyea L, Comas X, Reeve A, Slater L (eds) Northern peatlands and carbon cycling. American Geophysical Union, pp 187–203Google Scholar
- Johnson MS, Billett MF, Dinsmore KJ, Wallin M, Dyson K (2010) Direct in situ measurement of dissolved carbon dioxide in freshwater aquatic systems—method and applications. Ecohydrology 3:68–78Google Scholar
- Slota P, Jull AJT, Linick T, Toolin LJ (1987) Preparation of small samples for 14C accelerator targets by catalytic reduction of CO. Radiocarbon 29(2):303–306Google Scholar
- Stuiver M, Polach HA (1977) Reporting of 14C data. Radiocarbon 19(3):355–363Google Scholar