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Impacts of weathering, redox cycling and microbial activity on the formation of kaolinite (china clay). PhD in Mining and Minerals Engineering (NERC GW4 + DTP)

  • Full or part time
  • Application Deadline
    Monday, January 06, 2020
  • Competition Funded PhD Project (European/UK Students Only)
    Competition Funded PhD Project (European/UK Students Only)

Project Description

Lead Supervisor
Dr Laura Newsome, Camborne School of Mines, College of Engineering, Mathematics and Physical Sciences, University of Exeter

Additional Supervisors
Dr Heather Buss, School of Earth Sciences, University of Bristol
Dr Javier Cuadros, Department of Earth Sciences, Natural History Museum

Location: University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE

This project is one of a number that are in competition for funding from the NERC GW4+ Doctoral Training Partnership (GW4+ DTP). The GW4+ DTP consists of the GW4 Alliance of research-intensive universities: the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus five unique and prestigious Research Organisation partners: British Antarctic Survey, British Geological Survey, Centre for Ecology & Hydrology, the Natural History Museum and Plymouth Marine Laboratory. The partnership aims to provide a broad training in the Earth, Environmental and Life sciences, designed to train tomorrow’s leaders in scientific research, business, technology and policy-making. For further details about the programme please see http://nercgw4plus.ac.uk/

For eligible successful applicants, the studentships comprises:

- An stipend for 3.5 years (currently £15,009 p.a. for 2019/20) in line with UK Research and Innovation rates
- Payment of university tuition fees;
- A research budget of £11,000 for an international conference, lab, field and research expenses;
- A training budget of £3,250 for specialist training courses and expenses.
- Travel and accommodation is covered for all compulsory DTP cohort events.
- No course fees for courses run by the DTP

We are currently advertising projects for a total of 10 studentships at the University of Exeter


Project Background

Do microbes help make china clay? Kaolin minerals are very important economic resources; so much so that china clay has sometimes been referred to as “white gold”. Understanding how kaolin minerals form and behave in the environment is important because not only are they valuable economically, they also transport metals and nutrients to the ocean, can be used to remediate pollutants, and have been identified on the surface of Mars. Large kaolin deposits form from granites, either by hydrothermal alteration or by surface weathering in areas with temperate climates and high rainfall. Kaolin minerals also form in soils in intensely weathering environments. Kaolinization is thought to be triggered by the oxidation of iron(II) in biotite, and this has been linked to the activity of iron(II)-oxidising microorganisms. However, microbial iron(II) oxidation at neutral pH tends to occur in relatively narrow zones of redox interfaces rather than over tens of metres, which raises questions about its significance in economic kaolin deposits. This project will test the hypothesis that microbial redox cycling of iron contributes to kaolin formation in near surface environments, and therefore stimulating microbial redox cycling will increase the rate of kaolinization.

Project Aims and Methods

This project will characterise the conditions under which kaolinite forms during surface weathering of granites, investigate the role of microbial iron cycling and how this influences the rate of reaction, and consider how these processes can be enhanced to improve the kaolinization of low-grade materials by:

•Studying the composition of microbial communities in kaolin deposits (including those currently mined by Imerys at St Austell) using high throughput DNA sequencing.

•Observing the role of microorganisms in kaolinite formation and weathering by performing laboratory experiments with pure mineral phases and cultures of iron-reducing and iron-oxidising bacteria.

•Simulating weathering by performing sediment microcosm redox cycling experiments to observe the behaviour of kaolinite during biogeochemical cycling.

There will be the potential for fieldwork to collect samples from different kaolin deposits beyond the UK. Flexibilities exist for the student to be involved in experimental design and in decisions regarding choice of analytical techniques. We envisage the student will characterise samples using X-ray diffraction, scanning electron microscopy and synchrotron X-ray techniques (www.diamond.ac.uk/Home/About.html).

Overall this interdisciplinary research project links geology and biology to provide fundamental insights into the role of microbes in the formation of a highly important mineral resource. It will provide the student with a deep understanding of biogeochemical cycling, weathering, and environmental mineralogy, as well as providing skills for pursuing careers in academia, environmental consulting, industry or the public sector.

Funding Notes

NERC GW4+ funded studentship available for September 2020 entry. For eligible students, the studentship will provide funding of fees and a stipend which is currently £15,009 per annum for 2019-20.

References

References / Background reading list

Cuadros J., Afsin B., Jadubansa P., Ardakani M., Ascaso C. and Wierzchos J. (2013) Microbial and inorganic control on the composition of clay from volcanic glass alteration experiments. Am. Mineral. 98, 319-334. http://dx.doi.org/10.2138/am.2013.4272

Li G. L., Zhou C. H., Fiore S. and Yu W. H. (2019) Interactions between microorganisms and clay minerals: New insights and broader applications. Appl. Clay Sci. 177, 91–113. https://doi.org/10.1016/j.clay.2019.04.025

Minyard M. L., Bruns M. A., Liermann L. J., Buss H. L. and Brantley S. L. (2012) Bacterial associations with weathering minerals at the regolith-bedrock interface, Luquillo Experimental Forest, Puerto Rico. Geomicrobiol. J. 29, 792–803. http://dx.doi.org/10.1080/01490451.2011.619640

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