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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities

Lead supervisor: Alexander Piotrowski, Earth Sciences

Co-supervisors: Kate HendryBritish Antarctic SurveyMichael MeredithBritish Antarctic Survey; Mohamed Ezat, UiT Arctic University of Norway, Tromsø, Norway & Ian Millar, British Geological Survey

Brief summary: 
Disruption of ocean circulation by meltwater forcing is of great climatic importance, and also provides a natural laboratory to study marine geochemical cycling.
Importance of the area of research concerned: 
The extent to which ocean circulation is disrupted by meltwater forcing is of great climatic importance and hence societal relevance. Deep water mass formation occurs in the Arctic and Nordic Sea, where a major portion of North Atlantic Deep Waters forms, but this is also sensitive to meltwater inputs and climate change. High sedimentation rates in the Nordic Seas also make it an excellent place to use sediment cores to reconstruct past changes in ocean circulation and meltwater input. Neodymium (Nd) isotopes are widely applied tracers of deep water mass sources and advection, however the geochemical inputs and cycling of Nd in the modern ocean remains poorly understood. This is especially true in areas where there are major changes in weathering, meltwater, and sediment input. This project will focus on locations in the Arctic and Nordic Sea which are experiencing changes in meltwater input and deep water formation today, and which did so during past deglaciations. This will allow us to ground-truth Nd isotopes to modern climate processes, allowing an accurate interpretation of past climate and oceanographic changes.
Project summary : 
The Nordic Sea are an excellent natural laboratory to examine how Nd isotopes trace deep ocean circulation and are changed by sedimentary and geochemical processes. This is because the Nordic Sea hosts extremes in circulation, and sedimentary Nd input and scavenging. Each of these processes have distinct spatial patterns and there is a huge Nd isotopic contrast between inputs from surrounding continental sources, allowing distinguishing of sources and patterns of transport. Past climate change in this region affected ice sheet melting, ice rafted sediment input, and surface ocean circulation which were recorded in marine sediment cores and high-fidelity terrestrial records such as Greenland ice core records. The student will examine modern Nd cycling in collaboration with the NERC BIOPOLE programme, and reconstruct past changes in collaboration with the Norwegian ARCLIM project.
What will the student do?: 
The student will start by working with modern seawater and sediment samples, and will be linked with the BIOPOLE consortium, an interdisciplinary NERC programme examining biogeochemical processes and ecosystem function in polar ecosystems. This studentship will allow the expansion of the Nd isotope analysis in the Arctic, and build in process-based experimental studies to improve our understanding of Nd cycling in glaciated environments. The student will also reconstruct changes in Nd isotopes across major climate transitions, focusing on the most recent deglaciations, and while doing this will be working on sediment cores collected as part of the ARCLIM project. The student may have opportunities to join Arctic/Nordic cruises through UiT/ARCLIM to collect additional samples. The student will be able to work with other BIOPOLE and ARCLIM researchers from a variety of backgrounds, including physical oceanographers, ecologists, palaeoceanographers, and climate modellers, and contribute towards broader impact and outreach activities.
References - references should provide further reading about the project: 
Larkin C.S., Ezat, M.M., Roberts, N.L., Bauch, H.A., Spielhagen, R.F., Noormets, R., Polyak, L., Moreton, S.G., Rasmussen, T.L., Sarnthein, M., Tipper, E.T. and Piotrowski, A.M., (2022) Active Nordic Seas deep-water formation during the Last Glacial Maximum, Nature Geoscience, 24 October 2022,
Larkin, C.S., Piotrowski, A.M., Hindshaw, R.S., Bayon, G., Hilton, R.G., Baronas, J,, Dellinger, M., Wang, R., Tipper, E.T., (2021) Constraints on the source of reactive phases in sediment from a major Arctic river using neodymium isotopes. Earth and Planetary Science Letters 565, 116933.
Ezat, M.M., Rasmussen, T.L., Hain, M.P., Greaves, M., Rae, J.W.B, Zamelczyk, K., Marchitto, T.M., Szidat, S., and Skinner, L.C., (2021) Deep Ocean Storage of Heat and CO2 in the Fram Strait, Arctic Ocean During the Last Glacial Period, Paleoceanography and paleoclimatology 38, 8, e2021PA004216.
You can find out about applying for this project on the Department of Earth Sciences page.
Dr Alex Piotrowski