Aquatic carbon concentrations and fluxes in a degraded blanket peatland with piping and pipe outlet blocking

Abstract

Soil piping is an important agent of erosion in many environments, including blanket peatlands. Peatland restoration that aims to reduce erosion has mainly focussed on revegetation and blocking ditches and gullies, rather than reducing erosion from natural soil pipes. However, little is known about the contribution of pipeflow to the fluvial carbon budget of degraded blanket peatlands and whether it is possible to moderate it. In a heavily degraded blanket bog, dissolved and particulate organic carbon (DOC and POC), and water colour, from two catchments were compared before and after half of the pipe outlets in one catchment were blocked. One blocked pipe was monitored for discharge and water quality both pre-and post-blocking as new pipe outlets had formed around the blocked outlet. Both pre-and post-blocking, maximum concentrations of DOC and POC were markedly higher in pipe-water than stream-water, with ratios of 1.2 (pre) and 1.3 (post) for DOC, and 4.8 (pre) and 8.8 (post) for POC, rendering pipe-to-stream transfer more effective for DOC than POC due to the deposition of POC close to pipe outlets. The increase in DOC and POC flux post-blocking in both catchments was near-identical, suggesting pipe outlet blocking was ineffective in reducing fluvial carbon export from pipe networks.Extrapolation of pipe fluxes to catchment scale showed pipes potentially contribute c. 56% of DOC exported by the stream, and that more POC was produced by pipes than was exported by the stream. Our work highlights that pipes need to be considered when seeking to reduce fluvial carbon export in degraded blanket peatlands.

Can soil piping impact environment and society? Identifying new research gaps

“…Up to now, carbon loss in piping‐affected areas have been only studied in peatlands as these areas represent important global carbon stores (i.e., Billett et al, 2012; Dinsmore et al, 2011; Holden, 2005b, 2006; Regensburg et al, 2021). Generally, it has been suggested that pipes in peatlands play a dynamic (short‐term) and changing (long‐term) role in carbon loss and they release the terrestrially produced greenhouse gases [carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O)] to the atmosphere (Dinsmore et al, 2011).…”

“…A recent study has revealed that pipes potentially contribute c . 56% of DOC exported by the stream in degraded blanket peatlands (Regensburg et al, 2021).…”

“…Moreover, Billett et al (2012) proved that natural pipes vent old, deep peat CO 2 and particulate organic carbon [POC, but not dissolved organic carbon (DOC)] to the atmosphere. A recent study has revealed that pipes potentially contribute c. 56% of DOC exported by the stream in degraded blanket peatlands (Regensburg et al, 2021).…”

High frequency UV–Vis sensors estimate error in riverine dissolved organic carbon load estimates from grab sampling

“…The error in this load estimate is then assessed using the variance in the flow-weighted mean concentration (Hope et al, 1997 ). Recent examples of this technique being employed to estimate DOC loads or fluxes include Arízaga-Idrovo et al, 2022 ; Gaffney et al, 2020 , Pérez-Rodríguez & Biester, 2022 , Regensburg et al 2022 ; Rosset et al, 2019 and our own work in Ritson et al, 2019 .…”