Meteoric 10Be as a tracer of chemical weathering in glacial sediments (Advert Reference: RDF22/EE/GES/GRALY)

Our understanding of glaciation and its effects on global geochemical cycling depends on the extent to which glaciers inhibit or enhance chemical weathering. Where glaciers inhibit chemical weathering, they limit CO₂ drawdown into the oceans and thereby are self-limiting in an earth system sense. But where glaciers enhance chemical weathering, they maintain their own existence by removing heat trapping gases from the atmosphere. A difficulty in assessing these impacts is differentiating between products of chemical weathering (e.g. clays, oxides) that pre-date glaciation from those formed in glacial environments. The cosmogenic isotope meteoric ¹⁰Be has the potential to resolve these issues, as it is incorporated into the lattices of clays, oxides, and oxyhydroxides during chemical weathering. Thus, glacial sediments from below horizons where modern chemical weathering is occurring can preserve archives of subglacial and proglacial weathering processes.

The doctoral project will focus on two parts of this research topic. First, the doctoral student will seek to establish both contemporary and long-term deposition rates for meteoric ¹⁰Be in northern Britain (above the glacial limit). The latitude of northern Britain represents a gap in global measurements of ¹⁰Be fallout and therefore simple measurements of the isotope in precipitation are crucial to understanding the isotope’s distribution both locally and globally. The student will also measure the isotope’s concentration in dated archives that determine its fallout rate over longer timescales.

The second part of the project will focus on chemical weathering products within glacial sediments in northern Britain. The doctoral student will first analyse these sediments by conventional means, such as X-ray diffraction. Those rich in chemical weathering products, such as soil clays, will be analysed for ¹⁰Be within these specific mineral fractions. This will test the degree to which these weathering products date to the glacial period and therefore represent chemical weathering in the glacial environment. The behaviour of the isotope in modern soil environments will be contrasted as a control.

The doctoral student will be responsible for developing the project sampling strategy and is free to adapt the project to his or her interests. This could include analyses in other stable or radiogenic isotope systems. It would also be possible to add samples from additional sites. These could fill further gaps in the global distribution of meteoric ¹⁰Be fallout (i.e. low latitude or high altitude) or analyse the isotope’s chemical behaviour at other glaciated sites (i.e. Greenland, Antarctica, alpine glaciers).

The project will take place in close collaboration with the National Environmental Isotope Facility at Scottish Universities Environmental Research Centre (SUERC), where the doctoral student will be trained in isotope analysis methods. The project will tie into supervisor Graly’s existing projects on chemical weathering in glacial environments, and therefore allow collaboration with American, Norwegian, and Israeli colleagues. Upon completion, the student will be qualified to pursue an academic career employing chemical and isotopic methods to analyse earth system feedbacks or to work in range of industry or government positions (e.g. energy, environmental) that depend on the analysis of geochemical or mineralogical data.

The Principal Supervisor for this project is Dr. Joseph Graly.

Eligibility and How to Apply:

Please note eligibility requirement:

• Academic excellence of the proposed student i.e. 2:1 (or equivalent GPA from non-UK universities [preference for 1st class honours]); or a Masters (preference for Merit or above); or APEL evidence of substantial practitioner achievement.
• Appropriate IELTS score, if required.
• Applicants cannot apply for this funding if currently engaged in Doctoral study at Northumbria or elsewhere or if they have previously been awarded a PhD.

For further details of how to apply, entry requirements and the application form, see

https://www.northumbria.ac.uk/research/postgraduate-research-degrees/how-to-apply/

Please note: Applications that do not include a research proposal of approximately 1,000 words (not a copy of the advert), or that do not include the advert reference (e.g. RDF22/…) will not be considered.

Deadline for applications: 18 February 2022

Start Date: 1 October 2022

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