Project 1. Redox controls of Cr and U mobility in natural waters

Primary Employer: Oxford University, Department of Earth Sciences, Oxford, UK

PhD Programme: Oxford University (3 years)

The environmental speciation and mobility of highly toxic Cr and U is controlled primarily by redox processes. In oxidising environments, soluble and bioavailable Cr6+ and U6+ species predominate, but under reducing conditions these partition to highly insoluble Cr3+ and U4+ oxides. Redox-induced shifts in Cr and U stable isotopic compositions in natural and contaminated land systems that could be used to identify the processes controlling migration behaviour have not yet been characterised. We will determine the isotopic fractionation that occurs during redox cycling by reacting Cr and U with a range of key Fe and Mn minerals (e.g. Fe3O4) and a range of natural sediments (i.e. microcosms). We will then compare this lab data to Cr and U isotope data from natural and contaminated sites to understand how stable isotope measurements can be used to quantify the biogeochemical processes controlling the speciation of Cr and U. This, in turn, could be used to inform risk assessment for contaminated land sites and models for the global cycling of U and Cr. There will be the opportunity to focus on various different environmental conditions and consider the behaviour of associated elements. The project will involve an ESR enrolled in the Oxford PhD programme. It is anticipated that the ESR will conduct a range of analyses in various labs in the MetTrans network, including isotopic analyses at Oxford and other isotope analysis labs, and mineralogical analyses at Leeds. We anticipate that microbial experiments will be done at Leeds and collaborative work will be done with Stockholm and Luleå. Also, the stable isotope data may be combined with radioisotope constraints on U transport in collaboration with Barcelona. Applications will be considered with industrial partners. The ESR will learn chemical separation techniques in a clean lab environment, obtain data using various high precision mass spectrometry methods, and model the geochemical behaviour of Cr and U.

Employment and eligibility

The PhD candidate will be based at the Oxford University Department of Earth Sciences, , employed with a MetTrans contract and enrolled in the Oxford University three year PhD programme.

Applicants should hold a degree in Earth Sciences, Environmental Sciences, Chemistry, or other relevant field.

As required by European Commission Marie Curie Training Network regulations, at the time of recruitment by the host organisation, applicants must be in the first four years (full-time equivalent) of their research careers (since the time of undergraduate degree or equivalent). Also, applicants must not have resided or carried out their main activity (work, studies, etc) in the UK for more than 12 months in the last 3 years.


Applicants should contact the supervisor: ( and a formal application should also be made using Oxford University’s on-line application form.

You should use project number EARTH-12-METTRANS1  on your application.

Female and minority applicants are encouraged to apply.

The deadline for the first round of admissions is March 30, 2012.