Submerged peatlands – Characterisation, Vulnerability and Management

Marine sediments store almost twice as much organic carbon as terrestrial soils, and can remain buried for millions of years if left undisturbed.  However, blue carbon is poorly accounted for in national and global carbon valuations, and the focus to date has been on coastal ecosystems (e.g., saltmarshes) and carbon buried within 10 cm of the seafloor.  Fundamental uncertainties remain, including how much carbon lies deeper below the seabed and what happens if it is disturbed.

During the last ice age, when sea levels were lower, what is now the southern North Sea comprised of extensive terrestrial peatlands. 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.

Objectives

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 CASE 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 CASE-partner 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.

Potential for high-impact outcomes

The results of this work will have multiple scientific outcomes, with interdisciplinary reach for the geoscience, carbon valuation, marine management and hazard-and-risk research communities. Potential high-impact outcomes of the work include:

• Improved understanding of the composition, biogeochemical processes within, and vulnerability to future degradation, of submarine peat carbon stores;
• Assessment of the vulnerability of peat carbon stores to future anthropogenic and environmental changes, from which to inform marine management strategies;
• Provide carbon stock and vulnerability estimates that will fed into ecosystem service valuation and economic assessments at national and international levels.

There is an increasing amount of offshore core material and geophysical data becoming available for analysis and growing interest in blue carbon and marine management; as result, this PhD could provide the springboard for many further opportunities working in these areas. This project aligns to many NERC research priorities including climate and climate change, geosciences (e.g., Quaternary science), geochemistry, terrestrial and freshwater environments (e.g., Earth system processes and ecosystem-scale processes).

Training, CASE partner and wider research group

This research project will build upon collaboration between the University of Leeds, the University of Bonn, University of St Andrews and Cefas, as well as existing research relationships with the Dutch Geological Survey (TNO), Utrecht University and Deltares. The successful candidate will have access to our extensive world-leading geochemistry laboratories within the Schools of Earth and Environment and Geography at Leeds, and University of Bonn, and benefit from networking opportunities through the Leeds Quaternary and peatland research groups in the Faculty. The lead supervisor (Natasha Barlow) is currently leader of a large European Research Council project (RISeR) which focuses on the Last Interglacial environments in the southern North Sea that is complementary to this PhD.

CASE partner Cefas will provide an additional £3.5k over the 3.5 years of the studentship to enhance the student’s research training support grant (RTSG). There will be opportunities for one or more research placements (a minimum of 3-months) at Cefas. This will provide the student the chance to be embedded into a policy-driven science environment and feed their work directly into complementary Cefas research and development on subtidal sedimentary organic carbon (stocks, characteristics, management) and marine natural capital (carbon mapping, pressure-vulnerability relationships, management scenarios).  The successful candidate will also have access to a broad spectrum of training workshops facilitated by the DTP at the University of Leeds. 

Student profile

The ideal candidate will have a background in geosciences or chemistry, with a relevant degree e.g. Geography, Environmental Science, Oceanography, Geology or Chemistry. A keen interest in laboratory work, geochemistry and environmental change is important.

Relevant publications by supervisory team

Emery AR, Hodgson DM, Barlow NLM, Carrivick JL, Cotterill CJ, Richardson J, Ivanovic R, Mellett C. 2020. Ice sheet and palaeoclimate controls on drainage network evolution: an example from Dogger Bank, North Sea. Earth Surface Dynamics. 8, pp. 869-891 https://doi.org/10.5194/esurf-8-869-2020

Graves, C. A., et al. (2022). Sedimentary carbon on the continental shelf: Emerging capabilities and research priorities for Blue Carbon. Frontiers in Marine Science 9:926215 https://doi.org/10.3389/fmars.2022.926215

März C, Butler PG, Carter GDO and Verhagen ITE (2021) Editorial: The Marine Carbon Cycle: From Ancient Storage to Future Challenges. Frontiers in Earth Science 9:748701. https://10.3389/feart.2021.748701

Woulds, C., Bell, J.B., Glover, A.G., Bouillon, S. and Brown, L.S., 2020. Benthic carbon fixation and cycling in diffuse hydrothermal and background sediments in the Bransfield Strait, Antarctica. Biogeosciences, 17(1), pp.1-12. https://doi.org/10.5194/bg-17-1-2020