Understanding how the nutrient phosphorus made Earth habitable
Life on Earth relies principally on 3 critical nutrients, carbon, nitrogen, and phosphorus. Carbon and nitrogen are abundant in the atmosphere, however, phosphorus is not and, therefore, is considered the key limiting nutrient for life over geological timescales. Consequently, the abundance of phosphorus in the oceans will control the rate of photosynthesis, which in turn influences CO2 drawdown and oxygen production. As a result phosphorus dictates environmental and biological change through time. For instance, an abundance of ocean phosphate 480 million years ago is believed to have sent the Earth into a global ice age and triggered the second largest mass extinction in Earth history (Lenton, et al., 2015). Similarly, an increase in phosphorus availability is believed to have contributed to the largest known mass extinction event, the Permian-Triassic mass extinction (Schobben et al., 2020).
In order to understand the causes and mechanisms behind biological and environmental change through time, a detailed understanding of phosphorus availability through time is required. This project will use a recently developed tool to measure ocean phosphate abundance through major events of biological and environmental change and identify how phosphorus made Earth habitable.
- Document changes in ocean phosphate during major events of biological and environmental change
- Identify the effects of metamorphism and diagenesis on the retention of phosphorus in carbonate sediments
- Identify the distribution of phosphorus in carbonate sediments
As part of this project the successful PhD applicant will:
- Develop a novel geochemical proxy to reconstruct ancient ocean phosphate concentrations
- Apply a geochemical tool to measure and reconstruct changes in ocean phosphate concentration during periods of biogeochemical upheaval
- Characterise carbonate sediments using petrographic techniques, such as optical, secondary electron microscopy, cathodoluminescence
- Conduct geological sampling in the field or in core archives
- Conduct geological sample preparation and geochemical analyses in the laboratory, making use of spectrophotometry; LA-ICP-MS; ICP-OES; ICP-MS
- Lenton, T. M., Crouch, M., Johnson, M., Pires, N., and Dolan, L., 2012, First plants cooled the Ordovician: Nature Geoscience, v. 5, no. 2, p. 86-89.
- Schobben, M., Foster, W. J., Sleveland, A. R. N., Zuchuat, V., Svensen, H. H., Planke, S., Bond, D. P. G., Marcelis, F., Newton, R. J., Wignall, P. B., and Poulton, S. W., 2020, A nutrient control on marine anoxia during the end-Permian mass extinction: Nature Geoscience.
- Shimura, T., Kon, Y., Sawaki, Y., Hirata, T., Han, J., Shu, D., and Komiya, T., 2014, In-situ analyses of phosphorus contents of carbonate minerals: Reconstruction of phosphorus contents of seawater from the Ediacaran to early Cambrian: Gondwana Research, v. 25, no. 3, p. 1090-1107.
Research team leader: Dr Matthew Dodd
I am a geochemist, with broad interests in the co-evolution of life and Earth; I am in the School of Earth Sciences at UWA. My research is focused on the effects of nutrient availability on the biosphere and geosphere. I am interested in how nutrients give rise to feedbacks between the evolution of life and its impact on planetary environments.
Alongside myself, Prof. Annette George brings to this project expertise in carbonate geology, mass extinction events and tectonic evolution of sedimentary basins.
Expressions of interest for this project can be sent via the EOI form below or by contacting - Professor Annette George
How to Apply
- To be accepted into the Doctor of Philosophy, an applicant must demonstrate they have sufficient background experience in independent supervised research to successfully complete, and provide evidence of English language proficiency
- Requirements specific to this project:
- Master’s degree in geoscience (geology, geochemistry)
- Desirable skills:
Geological fieldwork experience
Experience in carbonate petrography
Experience modelling or using mathematical software such as Matlab
Submit enquiry to research team leader
- Contact the research team leader by submitting an Expression of Interest form via the button below
- After you have discussed your project with the research team leader, contact firstname.lastname@example.org to proceed with your application