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QUADRAT DTP: Enhanced rock weathering – solution or problem? Potential human health risks from Ni and Cr accumulation in soils following repeated amendment with basalt dust

   School of Natural and Built Environment

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  Dr S Cox, Dr A Brasier  No more applications being accepted  Competition Funded PhD Project (Students Worldwide)

About the Project

In order to address the climate emergency and prevent catastrophic climate change, we must reduce our greenhouse gas (GHG) emissions to net-zero as quickly as possible. As humanity races to decarbonise all our activities, it has become apparent that although we must reduce GHG emissions in every sphere of our lives, some processes essential to our life on this planet are unlikely to ever become completely carbon neutral. Therefore, in additional to a radical reduction in GHG emissions, IPCC (2018) predict that part of the solution to achieving a net-zero carbon world will be to remove carbon dioxide (CO2) directly from the air.

Enhanced Rock Weathering (ERW) has been identified as a potentially promising technique for capturing CO2 from the atmosphere and sequestering it in soil, with a recent study claiming that ERW could meet 45% of the UK’s net-zero carbon removal target (Kantzas et al., 2022). Natural rock weathering happens slowly with CO2 being removed from the atmosphere over thousands of years as silicate rocks, rich in either magnesium and/or calcium are chemically broken down to release base cations which can react with CO2 to produce carbonate minerals. In ERW, pulverised silicate rocks are added to soils. The high reactive surface area of the pulverised rock accelerates natural weathering processes and therefore has potential to sequester significant quantities of atmospheric CO2. However, silicate rocks, including olivine-rich ultramafic and mafic rocks (basaltic) rocks, often contain trace metals including chromium (Cr) and nickel (Ni) that are toxic to humans and the environment at elevated levels (Cox et al., 2017). These trace elements are likely to be released during the enhanced weathering process, and therefore excessive use of ERW may locally pose risks to human health and the environment.

This PhD will investigate the risks to human health posed by Cr and Ni in soils enhanced with pulverised basalt. This will be done by analysing for bioaccessible Ni and Cr concentrations using the Unified BARGE Method for bioaccessibility testing and considering whether the released Cr and Ni is available for plant uptake. The rate of carbon sequestration in soils will be assessed using C and O isotope analysis. The student will benefit from access to community gardens developed as part of a collaboration between QUB and Belfast City Council as part of the Horizon 2020 funded UPSURGE project and will work with GSNI to identify a suitable quarry to source local quarry dusts.

Candidate Background: The successful candidate should have a 2.1 Honours Degree or MSc equivalent in Earth/Environmental Science or other related discipline. 

Experience in some of the following fields and a willingness to become familiar with the others:

  • Laboratory techniques and extractions
  • Soil geochemistry
  • Statistical analysis of environmental and geospatial data.

Ability to organise resources, manage time and meet deadlines.

Good communication skills in English (written and verbal).

Strong analytical and problem solving skills.

Ability to logically conceptualise and summarise research findings.

The following criteria are desirable, but not essential:

  • Experience of environmental risk assessment.
  • Experience of undertaking spatial, statistical and/or chemometric methods of analysis.
  • Knowledge of weathering processes.
  • Experience in using statistical software packages including ArcGIS or R.

More project details are available here:

How to apply: 

Funding Notes

QUADRAT studentships are open to UK and overseas candidates. Funding covers:
• A monthly stipend for accommodation and living costs, based on UKRI rates (currently £17,668 pa for 2022/23, updated annually)
• Fees (home rate tuition fees and/or fee waiver for overseas fees, where applicable)
• Research and training costs
For further information before applying please check full funding and eligibility information:


Cox, S. F., Rollinson, G., McKinley, J. M. (2017) Mineralogical characterisation to improve understanding of oral bioaccessibility of Cr and Ni in basaltic soils in Northern Ireland. Journal of Geochemical Exploration, Volume 183, Part B, 166-177.
Intergovernmental Panel on Climate Change (IPCC) (2018) Global Warming of 1.5 °C. An IPCC Special Report on the Impacts of Global Warming of 1.5 °C Above Pre-Industrial Levels and Related Global Greenhouse Gas Emission Pathways, World Meteorological Organization.
Kantzas, E. P. et al. (2022) ‘Substantial carbon drawdown potential from enhanced rock weathering in the United Kingdom’, Nature Geoscience. Springer US, 15(5), pp. 382–389. doi: 10.1038/s41561-022-00925-2.

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