Peatland pools are tightly coupled to the contemporary carbon cycle

Dean, J. F., Billett, M. F., Turner, T. E., Garnett, M. H. , Andersen, R., McKenzie, R. M., Dinsmore, K. J., Baird, A. J., Chapman, P. J. and Holden, J. (2024) Peatland pools are tightly coupled to the contemporary carbon cycle. Global Change Biology, 30(1), e16999. (doi: 10.1111/gcb.16999) (PMID:37921241)

Abstract

Peatlands are globally important stores of soil carbon (C) formed over millennial timescales but are at risk of destabilization by human and climate disturbance. Pools are ubiquitous features of many peatlands and can contain very high concentrations of C mobilized in dissolved and particulate organic form and as the greenhouses gases carbon dioxide (CO2) and methane (CH4). The radiocarbon content (14C) of these aquatic C forms tells us whether pool C is generated by contemporary primary production or from destabilized C released from deep peat layers where it was previously stored for millennia. We present novel 14C and stable C (δ13C) isotope data from 97 aquatic samples across six peatland pool locations in the United Kingdom with a focus on dissolved and particulate organic C and dissolved CO2. Our observations cover two distinct pool types: natural peatland pools and those formed by ditch blocking efforts to rewet peatlands (restoration pools). The pools were dominated by contemporary C, with the majority of C (~50%–75%) in all forms being younger than 300 years old. Both pool types readily transform and decompose organic C in the water column and emit CO2 to the atmosphere, though mixing with the atmosphere and subsequent CO2 emissions was more evident in natural pools. Our results show little evidence of destabilization of deep, old C in natural or restoration pools, despite the presence of substantial millennial-aged C in the surrounding peat. One possible exception is CH4 ebullition (bubbling), with our observations showing that millennial-aged C can be emitted from peatland pools via this pathway. Our results suggest that restoration pools formed by ditch blocking are effective at preventing the release of deep, old C from rewetted peatlands via aquatic export.

• Item Type: Articles
• Additional Information: This work was supported by the United Kingdom Natural Environment Research Council (NERC) grant NE/J007609/1 and NERC Radiocarbon allocation 1832.0514. JFD received additional support from NERC grant NE/V009001/1 and a United Kingdom Research and Innovation Future Leaders Fellowship MR/V025082/1.
• Keywords: Radiocarbon (14C), stable carbon isotope (δ13C), peatlands, pools/ponds, dissolved organic carbon (DOC), particulate organic carbon (POC), carbon dioxide (CO2), methane (CH4).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Garnett, Dr Mark

Creator Roles

Garnett, M.: Formal analysis, Investigation, Methodology, Validation, Writing – review and editing
Garnett, M. H.: Conceptualization

• Authors: Dean, J. F., Billett, M. F., Turner, T. E., Garnett, M. H., Andersen, R., McKenzie, R. M., Dinsmore, K. J., Baird, A. J., Chapman, P. J., and Holden, J.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Global Change Biology
• Publisher: Wiley
• ISSN: 1354-1013
• ISSN (Online): 1365-2486
• Published Online: 03 November 2023
• Copyright Holders: Copyright: © 2023 The Authors
• First Published: First published in Global Change Biology 30:e16999
• Publisher Policy: Reproduced under a Creative Commons licence