Degree type
PhD
Closing date
25 September 2023
Campus
Hobart
Citizenship requirement
Domestic / International
About the research project
The input and dissolution of continental material to high nutrient surface waters of the Southern Ocean plays an important role in biogeochemical cycling of carbon because it alleviates iron limitation and stimulates phytoplankton growth. Close to Antarctica, dissolved iron sources include melting sea ice, icebergs calved from glaciers, and upwelled deep waters. The Antarctic Ice Sheet is experiencing rapid changes in response to anthropogenic climate warming. Melting ice shelves and glacier retreat will increase the input of freshwater and dissolved continental material to the surface ocean, but the biological response to these changes (and therefore impact on the global carbon cycle) is unknown. The focus of this PhD project is to determine the sources and quantify the flux of dissolved iron along the continental margin of East Antarctica and compare these data to similar measurements across the Southern Ocean.
This project will focus on samples collected on the 2024 RV Investigator GEOTRACES voyage from Perth to East Antarctica. A suite of geochemical methods will be applied to seawater, aerosols, suspended particles, sea ice cores and sediment traps to quantify the input of iron to the Southern Ocean from different sources. Thorium isotopes and trace metals will be applied to estimate the supply of iron from lithogenic sources associated with glacial and sea ice melt, benthic sediments, and dust deposition. Thorium is very insoluble in seawater and as it dissolves from continental material it rapidly adsorbs to the surface of particles, making it an excellent tracer of dissolved components. Neodymium isotopes trace the source of particles and the chemical interactions at the continental-ocean boundary. The mineralogy of aerosols and particles will be investigated using scanning electron microscopy and Fe speciation assessed using X-ray Absorption Spectroscopy analysis following Shoenfelt et al. (2018) in collaboration with ANSTO. Leaching experiments on aerosol and suspended particles following Roy et al. (2013) and Robinson et al. (2008) will also be applied to investigate the bioavailability of different iron sources. Further investigation into the provenance of sedimentary Fe could also be applied using radiogenic isotopes (Pb, Nd and Sr).
Aims/Objectives
- Determine the dissolved trace metal distribution along East Antarctic margin and 19S repeat hydrographic section at 115°E following Wuttig et al. (2019) and Th and Nd isotopic composition following Perez-Tribouiller et al. (2019).
- Determine the aerosol and particulate filter mineralogy using facilities at the Utas Central Science Lab (Raman, ESD-SEM) and use X-ray Absorption Spectroscopy (ANSTO) to determine the redox Fe speciation.
- Conduct leaching experiments on aerosols and suspended particles to investigate the bioavailability of Fe.
- Assess the relationship between the dissolved 232Th/230Th in the overlying water column and the adsorbed 232Th/230Th measured in suspended particles.
- Use the 232Th/230Th ratio to calculate the dissolved iron flux using the Th/Fe ratio and solubility variables and compare to dissolved trace metal data.
Primary Supervisor
Meet Dr Taryn NobleFunding
Applicants will be considered for a Research Training Program (RTP) scholarship or Tasmania Graduate Research Scholarship (TGRS) which, if successful, provides:
- a living allowance stipend of $31,500 per annum (2023 rate, indexed annually) for 3.5 years
- a relocation allowance of up to $2,000
- a tuition fees offset covering the cost of tuition fees for up to four years (domestic applicants only)
If successful, international applicants will receive a University of Tasmania Fees Offset for up to four years.
As part of the application process you may indicate if you do not wish to be considered for scholarship funding.
Additional funding
This project is part of the ARC Australian Centre for Excellence in Antarctic Science (ACEAS). Candidates will be considered and assessed for ACEAS top-up scholarship eligibility (valued at $5,000 per annum for 3.5 years) upon ranking of the applicants by our GRCs and alignment of the project with ACEAS.
Other funding opportunities and fees
For further information regarding other scholarships on offer, and the various fees of undertaking a research degree, please visit our Scholarships and fees on research degrees page.
Eligibility
Applicants should review the Higher Degree by Research minimum entry requirements.
Ensure your eligibility for the scholarship round by referring to our Key Dates.
Additional eligibility criteria specific to this project/scholarship:
- Applicants must be able to undertake the project on-campus
Selection Criteria
The project is competitively assessed and awarded. Selection is based on academic merit and suitability to the project as determined by the College.
Application process
- Select your project, and check that you meet the eligibility and selection criteria, including citizenship;
- Contact Dr Taryn Noble to discuss your suitability and the project's requirements; and
- In your application:
- Copy and paste the title of the project from this advertisement into your application. If you don’t correctly do this your application may be rejected.
- Submit a signed supervisory support form, a CV including contact details of 2 referees and your project research proposal.
- Apply prior to 25 September 2023.
Full details of the application process can be found under the 'How to apply' section of the Research Degrees website.
Following the closing date applications will be assessed within the College. Applicants should expect to receive notification of the outcome by email by the advertised outcome date.
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