Bio-protection: long-term modification of rock weathering by microorganisms?
This project investigates how microorganisms effect the rate of rock weathering.
The studentship is part of the ARIES doctoral training partnership, funded by NERC and starts October 2020.
One of the most important questions related to the critical zone research and long-term climate stability is how biology influences weathering. This PhD project investigates a crucial question of Earth’s biogeochemistry: do microorganisms accelerate rock weathering or slow it down under environmentally relevant conditions?
Because microorganisms have been extracting nutrients and energy from rocks for ~3.7 billion years there is a mutual life-lithosphere modification, which is not yet well-explored. Very slow weathering observed at the field scale contradicts the idea of microbially enhanced rapid weathering from experimental studies.
Therefore, it is important to test the hypothesis that microbial biofilms around minerals inhibit weathering by regulating the transport and loss of weathering products. Knowing the metabolic diversity of microbial communities, grain-scale interactions between microbial communities and minerals, and the weathering intensity is important to link the roles of biological agents to erosion and climatic change.
Gran Canaria (Canary Islands) is a natural laboratory providing two essential constraints for the project:
- Volcanic rocks of homogeneous composition and the same age
- Large differences of rainfall inducing large differences of microbial development in soils
This PhD project will apply cutting edge chemical, mineralogical, isotopic and microbiology techniques and bioinformatics to determine the relationship between soil weathering rates, atmospheric precipitation and microbial communities and assess how microorganisms modify weathering intensities. U series isotopic disequilibrium (234U/238U) in porewater/stream water and soils will be used to independently constrain the weathering intensity.
The student will obtain training in field work and sample collection in Gran Canaria. They will receive training in X-ray diffraction, wet chemical analysis methods, molecular, microbiology techniques and bioinformatics (environmental DNA, high throughput sequencing, microbial community structure analysis, metagenomics and phylogenetic interference) at NHM.
They will also receive training in clean lab techniques and isotopic measurements using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) at RHUL. They will gain highly interdisciplinary quantitative geochemical skills integrating mineralogical, microbial, chemical and isotopic data.
A good background in Earth Sciences, preferably with some knowledge of chemistry and biology.
ARIES studentships are available to UK and EU applicants only.
Residency rules apply. In general, UK and EU nationals who will have been resident in the UK for three years or more at the time when their PhD begins will be eligible for a full ARIES studentship. UK and EU nationals who have been resident outside the UK but within the EU during the qualifying period will usually be eligible for a ‘fees only’ studentship, which pays research costs and tuition fees but gives no help with living expenses.
In case of uncertainty, the planned university of registration should be contacted for eligibility advice; or the ARIES administrators.
All applicants need to comply with the registered university's English-language requirements.
How to apply
Applications for the PhD are processed via the Royal Holloway Direct website.
Applications will need to be supported by:
- A full CV
- A statement that gives (for example) details of the candidate’s interest in the studentship project, and any skills etc they can bring to it
- Electronic copies of certificate(s) and transcript(s) for all relevant qualifications (degrees etc)
- Two references, of which at least one must be an academic reference.
The application deadline is 7 January 2020.
S. L. Brantley et al (2011) Twelve testable hypotheses on the geobiology of weathering. Geobiology 9, 140-165.
Javier Cuadros, Mara Cesarano, William Dubbin, Stuart W. Smith, Alexandra Davey, Baruch Spiro, Rodney G.O. Burton, Anne D. Jungblut (2018) Slow weathering in a sandstone-derived Podzol (Falkland Islands) resulting in high content of a non-crystalline silicate. American Mineralogist 103, 109- 124.
Mitchell, R.L., Cuadros, J., Duckett, J.G., Edgecombe, G.D., Mavris, C., Pressel, S., Sykes, D., Kenrick, P. (2016) Mineral weathering and soil development in the earliest land-plant ecosystems. Geology 44, 1007-1010.
Anirban Basu, Shaun T. Brown, John N. Christensen, Donald J. DePaolo, Paul W. Reimus, Jeffrey M. Heikoop, Giday Woldegabriel, Ardyth M. Simmons, Brian M. House, Matt Hartmann, and Kate Maher (2015). Isotopic and Geochemical Tracers for U(VI) Reduction and U Mobility at an in Situ Recovery U Mine. Environmental Science & Technology 2015 49 (10), 5939-5947
Li L. et al (2018). Weathering dynamics reflected by the response of riverine uranium isotope disequilibrium to changes in denudation rate. Earth and Planetary Science Letters. 500, 136- 144.
The ARIES (Advanced Research and Innovation in the Environmental Sciences) doctoral training partnership draws together expertise from five universities and nine research centres, as well as over forty other research-users.