The Potential Hidden Age of Dissolved Organic Carbon Exported by Peatland Streams

Joshua F. Dean*, Mark H. Garnett, Evangelos Spyrakos, Michael F. Billett

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Radiocarbon ( 14 C) is a key tracer for detecting the mobilization of previously stored terrestrial organic carbon (C) into aquatic systems. Old C (>1,000 years BP) may be “masked” by postbomb C (fixed from the atmosphere post-1950 CE), potentially rendering bulk aquatic dissolved organic C (DOC) 14 C measurements insensitive to old C. We collected DOC with a modern 14 C signature from a temperate Scottish peatland stream and decomposed it to produce CO 2 under simulated natural conditions over 140 days. We measured the 14 C of both DOC and CO 2 at seven time points and found that while DOC remained close to modern in age, the resultant CO 2 progressively increased in age up to 2,356 ± 767 years BP. The results of this experiment demonstrate that the bulk DO 14 C pool can hide the presence of old C within peatland stream DOC export, demonstrating that bulk DO 14 C measurements can be an insensitive indicator of peatland disturbance. Our experiment also demonstrates that this old C component is biologically and photochemically available for conversion to the greenhouse gas CO 2 , and as such, bulk DO 14 C measurements do not reflect the 14 C signature of the labile organic C pool exported by inland water systems more broadly. Moreover, our experiment suggests that old C may be an important component of CO 2 emissions to the atmosphere from peatland aquatic systems, with implications for tracing and modeling interactions between the hydrological and terrestrial C cycles.

Original languageEnglish
Pages (from-to)328-341
Number of pages14
JournalJournal of Geophysical Research: Biogeosciences
Volume124
Issue number2
Early online date2 Feb 2019
DOIs
Publication statusPublished - Feb 2019

Funding

We thank the staff at the NERC Radiocarbon Facility (NRCF010001) and the SUERC AMS Laboratory. We are grateful to Prof. Jesus Torres Palenzuela of University of Vigo for the fluorescence measurements; to Ian Washbourne and Kerry Dinsmore at the Centre for Ecology and Hydrology, Penicuik, UK, for the field CO2 and CH4 concentration analyses; and to Ype van der Velde at Vrije Universiteit Amsterdam for his assistance with the age distribution calculations. We also thank two anonymous reviewers and the Editor for their constructive comments that substantially improved this paper. This work was supported by the NERC Radiocarbon Facility NRCF010001 (allocation number 1855.1014). J. F. D. received partial support from the program of the Netherlands Earth System Science Centre (NESSC), financially supported by the Ministry of Education, Culture and Science (OCW) (grant number 024.002.001). The data supporting these conclusions are all included within the paper itself or the supporting informa tion accompanying it. Any requests for further information or data should be directed to J. F. D. The authors declare no competing financial interest.

FundersFunder number
NERC Radiocarbon Facility1855.1014
SUERC AMS Laboratory
Natural Environment Research CouncilNRCF010001
Ministerie van Onderwijs, Cultuur en Wetenschap024.002.001
Universidade de Vigo
Netherlands Earth System Science Centre

    Keywords

    • aquatic carbon cycle
    • aquatic respiration
    • carbon dioxide (CO )
    • dissolved organic carbon (DOC)
    • peatlands
    • radiocarbon ( C)

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