Project Background
It has been suggested that high phosphate and nutrient concentrations in post-Snowball oceans some 720-635 million years (Myr) ago, stimulated the rise of Earth’s atmospheric oxygenation content to present-day levels, promoting biological evolution and ultimately the rise and timing of the emergence of animals. For example, our work on the Snowball glaciation in Islay, Scotland 720-650 Myr ago, points to large-scale grinding of the continents by the colossal ice sheets that covered the entire Earth surface, combined with chemical weathering during deglaciation, generated tiny buoyant particles in association with glacial rock flour that provided a freeboard for P delivery to the oceans. Upon contact with seawater salinity and pH, this P detached, dissolved, and raised seawater P concentrations by over 200 times compared to concentrations before the glaciations. CryoPhosphate aims to test this hypothesis on glacial rock flour samples issuing from modern glaciers, linked to laboratory CO2 weathering experiments, quantification of dissolved nutrient enrichment in experiments and receiving seawater and the impact on known photosynthetic cyanobacteria that first emerged to global prominence some 1000 Myr ago.
Project Aims and Methods
The aim of this project is to develop an empirical understanding on how nutrients released by glaciers (particularly phosphate) became available to life in the early oceans and how this contributed towards the early oxygenation of the atmosphere and oceans. To achieve this, glacial flour will be collected from glaciers terminating in the sea and rivers in the Arctic, the Canadian Rocky Mountains and Northern Sweden. After comparative geochemistry, mineralogical analysis and associated biological processes, samples will be incubated in early seawater conditions under present day atmospheric levels (PAL) of CO2 and in the up to 350 times PAL concentrations that followed the Snowball state. Accelerated chemical weathering and nutrient release into solution will be quantified. The rates of the primary production these nutrients support will be assessed in photosynthetic cyanobacteria experiments and compared to activity in their natural environment. Experiments will be accompanied by geochemical analysis, including Sr isotope analysis to measure weathering intensities, trace element cycling, and oxygen isotopes in phosphate to assess biotic and abiotic phosphate cycling pathways. This will be combined with C and N isotopes to evaluate impacts on the fractionation of C and N isotopes by comparison with sedimentary signals, Sr isotopes, and nutrient levels across the Sturtian Snowball glacial deposits on Islay and the Garvellach Islands, Scotland.
Candidate Requirements
The successful applicant for this position would have a good background in Earth Sciences. They should be willing to perform multidisciplinary research by undertaking cutting-edge research tasks in geomicrobiology, geochemistry and biogeochemistry over long geological timescales.
CASE or Collaborative Partner
The student will be exposed to world-class stable isotope facilities, working closely with facility staff to learn both laboratory techniques for the extraction of phosphate oxygen isotopes and have hands on experience running several stable isotope mass spectrometers. This will provide the student with a good laboratory working background and the experience of working away from their host institution.
Training
The successful candidate will acquire a PhD degree and training in the Earth sciences, with a specific skill set in geomicrobiology, biogeochemistry and isotope geochemistry. Through the extensive network of supervisors, they will gain international collaborative skills, presentation skills, and publish scientific articles in high standing and reputable peer review journals. There are opportunities for fieldtrip work in Arctic locations locations in Canada and Sweden, taking into account the present Covid-19 pandemic.
HOW TO APPLY
In order to formally apply for the PhD you will need to go to the following web page:
https://www.cardiff.ac.uk/study/postgraduate/research/programmes/programme/earth-sciences
In the black box on the right of the page please select the following options:
• Doctor of Philosophy
• Full Time
• 1st October 2021
Click on ‘Apply now’.
Please ensure that you include the ‘Project Title’ you are applying for and supervisor and that you add ‘NERC DTP’ under the source of funding.
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