Abundant pre-industrial carbon detected in Canadian Arctic headwaters: Implications for the permafrost carbon feedback

J. F. Dean; Y. Van Der Velde; M. H. Garnett; K. J. Dinsmore; R. Baxter; J. S. Lessels; P. Smith; L. E. Street; J. A. Subke; D. Tetzlaff; I. Washbourne; P. A. Wookey; M. F. Billett

doi:10.1088/1748-9326/aaa1fe

Abundant pre-industrial carbon detected in Canadian Arctic headwaters: Implications for the permafrost carbon feedback

J. F. Dean^*, Y. Van Der Velde, M. H. Garnett, K. J. Dinsmore, R. Baxter, J. S. Lessels, P. Smith, L. E. Street, J. A. Subke, D. Tetzlaff, I. Washbourne, P. A. Wookey, M. F. Billett

^*Corresponding author for this work

Earth and Climate

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

Mobilization of soil/sediment organic carbon into inland waters constitutes a substantial, but poorly-constrained, component of the global carbon cycle. Radiocarbon (¹⁴C) analysis has proven a valuable tool in tracing the sources and fate of mobilized carbon, but aquatic ¹⁴C studies in permafrost regions rarely detect 'old' carbon (assimilated from the atmosphere into plants and soil prior to AD1950). The emission of greenhouse gases derived from old carbon by aquatic systems may indicate that carbon sequestered prior to AD1950 is being destabilized, thus contributing to the 'permafrost carbon feedback' (PCF). Here, we measure directly the ¹⁴C content of aquatic CO₂, alongside dissolved organic carbon, in headwater systems of the western Canadian Arctic - the first such concurrent measurements in the Arctic. Age distribution analysis indicates that the age of mobilized aquatic carbon increased significantly during the 2014 snow-free season as the active layer deepened. This increase in age was more pronounced in DOC, rising from 101-228 years before sampling date (a 120%-125% increase) compared to CO₂, which rose from 92-151 years before sampling date (a 59%-63% increase). 'Pre-industrial' aged carbon (assimilated prior to ∼AD1750) comprised 15%-40% of the total aquatic carbon fluxes, demonstrating the prevalence of old carbon to Arctic headwaters. Although the presence of this old carbon is not necessarily indicative of a net positive PCF, we provide an approach and baseline data which can be used for future assessment of the PCF.

Original language	English
Article number	034024
Pages (from-to)	1-11
Number of pages	11
Journal	Environmental Research Letters
Volume	13
Issue number	3
DOIs	https://doi.org/10.1088/1748-9326/aaa1fe
Publication status	Published - 27 Feb 2018

Funding

This work was primarily supported by the UK Natural Environment Research Council (NERC), grant numbers NE/K000217/1, NE/K000225/1, NE/K000268/1 and NE/K000284/1. JFD acknowledges partial support by the program of the Netherlands Earth System Science Centre (NESSC), financially supported by the Ministry of Education, Culture and Science (OCW). We would like to thank the Aurora Research Institute in Inuvik, Prof Philip Marsh of Wilfrid Laurier University, Dr Oliver Sonnentag of Université de Montréal, and Dr Mark Cooper of the University of Exeter, for support during the field campaigns, Environment Canada for data access, Dr James Weedon of Vrije Universiteit Amsterdam for support with the statistical analyses, and the staff at the NERC Radiocarbon Facility (NRCF010001) and the SUERC AMS Laboratory for the 14C sample processing. The authors declare no competing financial interests. Requests for additional materials and data should be sent to J F Dean.

Funders	Funder number
Natural Environment Research Council	NE/K000284/1, NE/K000225/1, NE/K000268/1, NE/K000217/1
Ministerie van Onderwijs, Cultuur en Wetenschap
Netherlands Earth System Science Centre

Keywords

Arctic catchments
carbon dioxide CO
dissolved organic carbon DOC
inland waters
methane CH
radiocarbon 14

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1088/1748-9326/aaa1fe

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Dean, J. F., Van Der Velde, Y., Garnett, M. H., Dinsmore, K. J., Baxter, R., Lessels, J. S., Smith, P., Street, L. E., Subke, J. A., Tetzlaff, D., Washbourne, I., Wookey, P. A., & Billett, M. F. (2018). Abundant pre-industrial carbon detected in Canadian Arctic headwaters: Implications for the permafrost carbon feedback. Environmental Research Letters, 13(3), 1-11. Article 034024. https://doi.org/10.1088/1748-9326/aaa1fe

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abstract = "Mobilization of soil/sediment organic carbon into inland waters constitutes a substantial, but poorly-constrained, component of the global carbon cycle. Radiocarbon (14C) analysis has proven a valuable tool in tracing the sources and fate of mobilized carbon, but aquatic 14C studies in permafrost regions rarely detect 'old' carbon (assimilated from the atmosphere into plants and soil prior to AD1950). The emission of greenhouse gases derived from old carbon by aquatic systems may indicate that carbon sequestered prior to AD1950 is being destabilized, thus contributing to the 'permafrost carbon feedback' (PCF). Here, we measure directly the 14C content of aquatic CO2, alongside dissolved organic carbon, in headwater systems of the western Canadian Arctic - the first such concurrent measurements in the Arctic. Age distribution analysis indicates that the age of mobilized aquatic carbon increased significantly during the 2014 snow-free season as the active layer deepened. This increase in age was more pronounced in DOC, rising from 101-228 years before sampling date (a 120%-125% increase) compared to CO2, which rose from 92-151 years before sampling date (a 59%-63% increase). 'Pre-industrial' aged carbon (assimilated prior to ∼AD1750) comprised 15%-40% of the total aquatic carbon fluxes, demonstrating the prevalence of old carbon to Arctic headwaters. Although the presence of this old carbon is not necessarily indicative of a net positive PCF, we provide an approach and baseline data which can be used for future assessment of the PCF.",

keywords = "Arctic catchments, carbon dioxide CO, dissolved organic carbon DOC, inland waters, methane CH, radiocarbon 14",

author = "Dean, {J. F.} and {Van Der Velde}, Y. and Garnett, {M. H.} and Dinsmore, {K. J.} and R. Baxter and Lessels, {J. S.} and P. Smith and Street, {L. E.} and Subke, {J. A.} and D. Tetzlaff and I. Washbourne and Wookey, {P. A.} and Billett, {M. F.}",

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Dean, JF, Van Der Velde, Y, Garnett, MH, Dinsmore, KJ, Baxter, R, Lessels, JS, Smith, P, Street, LE, Subke, JA, Tetzlaff, D, Washbourne, I, Wookey, PA & Billett, MF 2018, 'Abundant pre-industrial carbon detected in Canadian Arctic headwaters: Implications for the permafrost carbon feedback', Environmental Research Letters, vol. 13, no. 3, 034024, pp. 1-11. https://doi.org/10.1088/1748-9326/aaa1fe

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T2 - Implications for the permafrost carbon feedback

AU - Dean, J. F.

AU - Van Der Velde, Y.

AU - Garnett, M. H.

AU - Dinsmore, K. J.

AU - Baxter, R.

AU - Lessels, J. S.

AU - Smith, P.

AU - Street, L. E.

AU - Subke, J. A.

AU - Tetzlaff, D.

AU - Washbourne, I.

AU - Wookey, P. A.

AU - Billett, M. F.

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N2 - Mobilization of soil/sediment organic carbon into inland waters constitutes a substantial, but poorly-constrained, component of the global carbon cycle. Radiocarbon (14C) analysis has proven a valuable tool in tracing the sources and fate of mobilized carbon, but aquatic 14C studies in permafrost regions rarely detect 'old' carbon (assimilated from the atmosphere into plants and soil prior to AD1950). The emission of greenhouse gases derived from old carbon by aquatic systems may indicate that carbon sequestered prior to AD1950 is being destabilized, thus contributing to the 'permafrost carbon feedback' (PCF). Here, we measure directly the 14C content of aquatic CO2, alongside dissolved organic carbon, in headwater systems of the western Canadian Arctic - the first such concurrent measurements in the Arctic. Age distribution analysis indicates that the age of mobilized aquatic carbon increased significantly during the 2014 snow-free season as the active layer deepened. This increase in age was more pronounced in DOC, rising from 101-228 years before sampling date (a 120%-125% increase) compared to CO2, which rose from 92-151 years before sampling date (a 59%-63% increase). 'Pre-industrial' aged carbon (assimilated prior to ∼AD1750) comprised 15%-40% of the total aquatic carbon fluxes, demonstrating the prevalence of old carbon to Arctic headwaters. Although the presence of this old carbon is not necessarily indicative of a net positive PCF, we provide an approach and baseline data which can be used for future assessment of the PCF.

AB - Mobilization of soil/sediment organic carbon into inland waters constitutes a substantial, but poorly-constrained, component of the global carbon cycle. Radiocarbon (14C) analysis has proven a valuable tool in tracing the sources and fate of mobilized carbon, but aquatic 14C studies in permafrost regions rarely detect 'old' carbon (assimilated from the atmosphere into plants and soil prior to AD1950). The emission of greenhouse gases derived from old carbon by aquatic systems may indicate that carbon sequestered prior to AD1950 is being destabilized, thus contributing to the 'permafrost carbon feedback' (PCF). Here, we measure directly the 14C content of aquatic CO2, alongside dissolved organic carbon, in headwater systems of the western Canadian Arctic - the first such concurrent measurements in the Arctic. Age distribution analysis indicates that the age of mobilized aquatic carbon increased significantly during the 2014 snow-free season as the active layer deepened. This increase in age was more pronounced in DOC, rising from 101-228 years before sampling date (a 120%-125% increase) compared to CO2, which rose from 92-151 years before sampling date (a 59%-63% increase). 'Pre-industrial' aged carbon (assimilated prior to ∼AD1750) comprised 15%-40% of the total aquatic carbon fluxes, demonstrating the prevalence of old carbon to Arctic headwaters. Although the presence of this old carbon is not necessarily indicative of a net positive PCF, we provide an approach and baseline data which can be used for future assessment of the PCF.

KW - Arctic catchments

KW - carbon dioxide CO

KW - dissolved organic carbon DOC

KW - inland waters

KW - methane CH

KW - radiocarbon 14

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Abundant pre-industrial carbon detected in Canadian Arctic headwaters: Implications for the permafrost carbon feedback

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