PhD: Submerged peatlands – carbon store or carbon source?

Shallow marine sediments play a vital role in regulating climate change by accumulating and burying carbon for up to millions of years – if left undisturbed. However, fundamental uncertainties remain as too the amount of carbon buried deeper (>10 cm) below the seabed and what happens if it is disturbed. The seabed is being developed for renewable energy and communication at an exponential rate, which may threaten these previously unaccounted for deeper marine carbon stores, risking carbon loss and transformation into greenhouse gases. But we just don’t know…and we’d like an exciting, motivated PhD student to join our team to find out! Utilising geochemical techniques this PhD project will help to ensure the future renewable energy developments are a sustainable solution to the climate crisis.

During the last ice age, when sea levels were lower, what is now the southern North Sea comprised of extensive terrestrial peatlands (Eaton et al., 2024). As the ice sheets melted, sea level rose, submerging this landscape to become the modern North Sea. Recent research at the University of Leeds has shown these now submerged peatlands contain organic carbon concentrations 30-40 times higher than the shallow marine sediments included in current marine sedimentary carbon inventories. However, these submarine peatlands are omitted from carbon budgets, their roles in carbon cycling and storage are not understood and their vulnerability to environmental change and human activities is unknown. Human disturbance (for example by offshore windfarm developments) may threaten these previously unaccounted for carbon stores, risking carbon loss and transformation into greenhouse gases. Therefore, it is critical to quantify and assess the vulnerability of these submerged organic carbon stocks as part of efforts to help stabilise global climate and understand their role as climate stores and potential risk as a carbon source. You can watch lead supervisor, Natasha, give a short presentation on the topic, here.

In this project, you will work with leading scientists in the School of Earth and Environment and School of Geography at the University of Leeds, as well as the Universities of Bonn and St Andrews, and project partner Cefas, to understand the carbon in now submerged peatlands. The supervisory team and Cefas have a wealth of expertise working on Quaternary landscapes in the North Sea region, the analysis of carbon in marine sediments and providing advice on blue carbon to UK policymakers. Specific objectives will be developed in collaboration with the student and Cefas and include, but are not limited to:

Characterisation of submarine peat and the surrounding “background sediment” from existing core material. Bulk organic and inorganic geochemistry (for example: CNS pyrolysis, stable isotope, thermogravimetric analysis, Rock-Eval pyrolysis XRF, XRD, pyrolysis GC-MS, FTIR) as well as sedimentology (grain size analysis, description of sedimentary structures, thicknesses etc) may be used to quantify the carbon, understand its reactivity and the processes the governed the peat formation.

Application of radiocarbon dating to constrain the date that the peat developed at each location, to establish a palaeo-environmental framework and depositional history for the different submarine peat settings based on geochemical and sedimentological data.

Calculation, based on sediment cores as well as existing geophysical data, to develop a 3D volume, and a carbon and sulphur budget for the analysed peat layers across the entire study area.