Carbon loss pathways in degraded peatlands: new insights from radiocarbon measurements of peatland waters

Evans, M. G. et al. (2022) Carbon loss pathways in degraded peatlands: new insights from radiocarbon measurements of peatland waters. Journal of Geophysical Research: Biogeosciences, 127(7), e2021JG006344. (doi: 10.1029/2021JG006344)

Abstract

Peatland carbon stores are under widespread anthropogenic pressure, resulting in degradation and carbon loss. This paper presents DO14C (Dissolved Organic Carbon) dates from waters draining two eroded blanket peatland catchments in the UK. Both catchments are characterized by severe gully erosion but one additionally has extensive surface erosion on unvegetated surfaces. DO14C values ranged from 104.3 to 88.6 percent modern (present to 976 Before Present). The oldest DOC dates came from the catchment characterized by both gully and surface erosion and are among the oldest reported from waters draining temperate peatlands. Together with peat age-depth data from across the peatland landscape, the DO14C ages identify where in the peat profile carbon loss is occurring. Source depths were compared with modeled water table data indicating that in the catchment where gully erosion alone dominated, mean water table was a key control on depth of DOC production. In the system exhibiting both gully erosion and surface erosion, DOC ages were younger than expected from the age of surficial peats and measured water tables. This may indicate either that the old organic matter exposed at the surface by erosion is less labile or that there are modifications of hydrological flow pathways. Our data indicate that eroded peatlands are losing carbon from depth, and that erosion form may be a control on carbon loss. Our approach uses point measurements of DO14C to indicate DOC source depths and has the potential to act as an indicator of peatland function in degraded and restored systems.

• Item Type: Articles
• Additional Information: This work was supported by NERC radiocarbon allocation NRCF010001 (allocation number 1657.1012) and by DEFRA grant SP1205.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Garnett, Dr Mark
• Authors: Evans, M. G., Alderson, D. M., Evans, C. D., Stimson, A., Allott, T. E.H., Goulsbra, C., Worrall, F., Crouch, T., Walker, J., Garnett, M. H., and Rowson, J.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Journal of Geophysical Research: Biogeosciences
• Publisher: American Geophysical Union
• ISSN: 2169-8953
• ISSN (Online): 2169-8961
• Published Online: 27 June 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Journal of Geophysical Research: Biogeosciences 127(7): e2021JG006344
• Publisher Policy: Reproduced under a Creative Commons License