A critical aspect of environmental studies is the understanding of how trace elements are distributed in surface deposits where they can cause toxicity in the water supply, animals and foodstuffs. In some districts of Britain and Ireland, shales are enriched in selenium, arsenic and other elements, which can be liberated during shale weathering. The project will assess factors which control how trace elements in shales behave, including the role of organic matter, the roles of mineral phases such as pyrite and apatite, and the degree of induration of the shale.
The distribution of trace elements will be examined in weathering/alteration products of the shales, including iron oxide, sulphate and carbonate minerals. The data will be interpreted to assess the degree to which potentially toxic elements may be available to the environment, as their mineral residence changes during alteration.
Case studies will include Carboniferous shales in Ireland (Clare Shale, Co. Kerry) and Britain (Bowland Shale, Lancashire), and Proterozoic shales in the Highlands and Islands of Scotland (Tiree, Glenelg), where pilot studies have shown anomalies. Selenium and arsenic are especially enriched in some Irish shales, and early accounts of environmental problems are recorded in Irish veterinary literature due to toxicity in livestock. The main case studies include dripping wet rock surfaces at a tourist resort (Ballybunion), iron oxide ochres in streams through farmland (Lancashire) and calcareous crusts in forestry land (Highlands).
Both Aberdeen and Belfast have track records of specialist research on selenium and arsenic, including research council funding, and are well placed to provide expert training in this field. Training will include field sampling, analytical techniques including electron microscopy, organic biomarker analysis, stable isotope compositions and chemical speciation. These techniques will give a good grounding suitable for a career in environmental science. In addition to membership of the vigorous QUADRAT student cohort, the student will interact with two active research groups, including main residence in Aberdeen within a group of fellow students undertaking geochemical research. The student will contribute to publication of research, which is an important activity in the group.
Candidates should have (or expect to achieve) a minimum of a 2.1 Honours degree in a relevant subject. Applicants with a minimum of a 2.2 Honours degree may be considered providing they have a Distinction at Master’s level.
• Apply for Degree of Doctor of Philosophy in Geosciences
• State name of the lead supervisor as ‘Name of Proposed Supervisor’ on application
• State ‘QUADRAT DTP’ as Intended Source of Funding
• Select https://www.abdn.ac.uk/pgap/login.php
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Armstrong, J.G.T., Parnell, J., Bullock, L.A., Boyce, A.J. Perez, M. & Feldmann, J. 2019. Mobilisation of arsenic, selenium and uranium from Carboniferous black shales in west Ireland. Applied Geochemistry, 109, 104401.
Parnell, J., Brolly, C., Spinks, S. & Bowden, S. 2016. Selenium enrichment in Carboniferous shales, Britain and Ireland: Problem or opportunity for shale gas extraction? Applied Geochemistry, 66, 82-87.
Parnell, J., Bullock, L., Armstrong, J. & Perez, M. 2018. Liberation of selenium from alteration of the Bowland Shale Formation: evidence from the Mam Tor Landslide. Quarterly Journal of Engineering Geology and Hydrogeology, 51, 503-508.