Integrated assessment of carbon fluxes in upland blanket peat

Abstract

As the importance of peatland carbon balances grows with Northern Ireland’s 2050 net-zero target and the planned restoration of 150,000 ha of degraded peatlands, accurate measurement of peatland carbon budgets is essential. To address this, research here developed the first full greenhouse gas (GHG) budget for an upland peatland in Northern Ireland.

Gaseous fluxes measured by a UKCEH eddy-covariance tower in the Glens of Antrim were combined with fluvial dissolved organic carbon (DOC) and particulate organic carbon (POC) loads, estimated using the mean of two interpolation methods over two overlapping hydrological years. Results showed the peatland acted as a net carbon sink, with GHG budgets of –2.32 and –2.87 t CO2e ha⁻¹ y⁻¹ for the first and second years, respectively. These values contrast with the UK Peatland Code emission factor of 3.32 t CO2e ha⁻¹ y⁻¹ for peatlands classified in similar condition and drainage status. This occurred despite hydroclimatic extremes, including a 20-day drought (May–June 2023) followed by record July rainfall (291 mm).

As interpolation methods using paired asynchronous data may miss high-discharge events, high-frequency DOC proxy sensors (fluorescence- and absorbance-based) were tested across environmental gradients and along a hydrological continuum. The fluorescence-based sensor experienced quenching at DOC concentrations above ~15 mg L⁻¹ and performed poorly during high flows, attributed to high humification.

The absorbance-based proxy was applied in a six-month comparison across three upland micro-catchments alongside the two interpolation methods. Concentration–discharge analysis showed that closely spaced high-flow events, even when dilutive, produced larger DOC loads. Overall, interpolation methods provided reasonable DOC load estimates relative to the proxy-based approach but will require further validation.

This research provides a baseline for refining upland peatland emission factors and improving DOC load estimation under high-flow conditions, with implications for regional and global peatland carbon accounting.

Thesis is embargoed until 31st August 2028

Date of Award	Aug 2026
Original language	English
Supervisor	Joerg Arnscheidt (Supervisor) & Phil Jordan (Supervisor)