PhD in Geographical & Earth Sciences: How life and steel slag interact – physical, chemical and biological breakdown of slag and the implications for remediation
Co-supervised by Professor Alistair Jump, University of Stirling
Worldwide, it is estimated that steelmaking produces up to 250 million tonnes of waste slag per year. Slag is typically dumped in heaps with little or no subsequent remediation. Steel slag is highly reactive so the interaction of rainwater with exposed slag heaps is known to release ecotoxic metals into surrounding water bodies. Partial remediation at some former steelmaking sites has involved capping with soil and planting of trees but this has been done with little or no long-term perspective of the processes involved.
While capping and planting can be a quick solution, it is extremely expensive and can fail when the cap is breached and plant roots, soil biota and water penetrate the slag below. In un-remediated sites, spontaneous revegetation occurs slowly, with plant communities adapted to the sites they colonise. However, interactions between vegetation and slag have the potential to alter slag weathering via physical (root penetration) and chemical (acid root exudates) means. Enhanced weathering of slag can lead to release of higher concentrations of toxic metals.
This project will investigate the physical and chemical processes occurring in slag heaps. Key research questions are:
• How do physical and chemical properties of steel slag vary with depth in a slag heap?
• Is there spatial variation in slag properties based on the degree of vegetation cover and is this influenced by the type of plant community?
• Does vegetation retard or enhance weathering (and therefore ecotoxic metal release) in slag heaps?
• Is natural colonising vegetation more effective than expensive engineering measures for remediation?
As steel works close in the UK, and steelmaking in developing countries with loose environmental regulation produces ever-increasing amounts of slag, it is critical to develop an understanding of the physical and chemical processes occurring in steel slag heaps and how these are influenced by vegetation. This characterisation will be the underpinning science that allows for effective and appropriate risk assessment and remediation measures to be taken.
Candidates are sought with the following qualities and backgrounds:
- A first or 2:1 undergraduate degree, or have relevant comparable experience;
- In addition, candidates may also hold or be completing a Masters degree in their area of proposed study or a related discipline; &
- An outstanding academic pedigree and research potential, such as evidenced through the publication of articles, participation in academic conferences and other similar activities.
Relevant disciplines include geoscience, environmental science, environmental chemistry, ecology, plant science, or similar. The successful candidate should have an interest in combining analytical chemistry methods with plant science to solve environmental pollution problems, and an aptitude for lab work.