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Annual variability in the radiocarbon age and source of dissolved CO2 in a peatland stream

Garnett, Mark H.; Dinsmore, Kerry J.; Billett, Michael F.. 2012 Annual variability in the radiocarbon age and source of dissolved CO2 in a peatland stream. Science of the Total Environment, 427-428. 277-285. 10.1016/j.scitotenv.2012.03.087

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Abstract/Summary

Radiocarbon dating has the capacity to significantly improve our understanding of the aquatic carbon cycle. In this study we used a new passive sampler to measure the radiocarbon (14C) and stable carbon (δ13C) isotopic composition of dissolved CO2 for the first time in a peatland stream throughout a complete year (May 2010–June 2011). The in-stream sampling system collected time-integrated samples of CO2 continuously over approximately 1 month periods. The rate of CO2 trapping was proportional to independently measured streamwater CO2 concentrations, demonstrating that passive samplers can be used to estimate the timeaveraged dissolved CO2 concentration of streamwater. While there was little variation and no clear trend in δ13CO2 values (suggesting a consistent CO2 source), we found a clear temporal pattern in the 14C concentration of dissolved CO2. The 14C age of CO2 varied from 707±35 to 1210±39 years BP, with the youngest CO2 in the autumn and oldest in spring/early summer. Mean stream discharge and 14C content of dissolved CO2 were positively correlated. We suggest that the observed pattern in the 14C content of dissolved CO2 reflects changes in its origin, with older carbon derived from deeper parts of the peat profile contributing proportionally more gaseous carbon during periods of low stream flow.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.scitotenv.2012.03.087
Programmes: CEH Topics & Objectives 2009 onwards > Biogeochemistry > BGC Topic 2 - Biogeochemistry and Climate System Processes > BGC - 2.2 - Measure and model surface atmosphere exchanges of energy ...
CEH Sections: Billett (to 30 Nov 2013)
ISSN: 0048-9697
Additional Information. Not used in RCUK Gateway to Research.: The attached document is the author’s version of a work that was accepted for publication in Science of the Total Environment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Science of the Total Environment, 427-428. 277- 285. 10.1016/j.scitotenv.2012.03.087
Additional Keywords: carbon dioxide, radiocarbon, streams, peatland, carbon
NORA Subject Terms: Ecology and Environment
Date made live: 28 May 2012 14:02
URI: http://nora.nerc.ac.uk/id/eprint/18185

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