ORGANISATION/COMPANYCNRS UMR 9012
RESEARCHER PROFILEFirst Stage Researcher (R1)Recognised Researcher (R2)Established Researcher (R3)Leading Researcher (R4)
APPLICATION DEADLINE27/06/2020 00:00 - Europe/Brussels
LOCATIONFrance › Orsay
TYPE OF CONTRACTTemporary
OFFER STARTING DATE01/10/2020
Chernobyl accident fallout and major radioactive water leaks from the damaged Fukushima Daiichi nuclear power plant arouse concerns regarding the potential radioactive contamination of aquatic systems and soils. The release into the environment of highly toxic actinides (An) and other radionuclides (RN) as a consequence of nuclear accidents, weapon tests, and waste processing/disposal all contribute to the radioactive contamination of soils and surface water.
The transfer of metal cations in soils and sediments is not only controlled by geological and physico-chemical parameters (clay and organic matter contents, pH, Eh, etc.) but also by microorganisms. As a matter of fact, the latter take part in the mobilisation/immobilisation of trace metals. Therefore, the presence of actinide(IV) (Pu, Th, etc.) contaminants after accidental discharges raises the question of their transfer in the environment and the resulting risk of food chain contamination.
Siderophores, as natural iron-specific chelators, must be considered in this context. These low molecular weight, hydrosoluble compounds are secreted by bacteria and fungi to overcome the limited bioavailability of iron under aerobic conditions by dissolution of iron oxohydroxides present in the soils.
The aim of this project is to characterize metal binding properties of siderophores in solution from structural and thermodynamic viewpoints for checking their efficiency in terms of affinity and selectivity. This information can be used not only for prediction on radionuclide migration in the environment, but also for the design of specific sensors for actinides (An(IV)), and of some tetravalent d-block metal cation surrogates (Zr(IV), Hf(IV)).
Firstly, complexation of Zr(IV) and Th(IV) will be studied with hydroxamic ligands. The methods used will be affinity capillary electrophoresis and liquid-liquid extraction with ICP-OES detection. U(IV) complexation will be studied by spectrophotometry. Preliminary studies will be performed to find the optimal conditions for complexation studies. Our partner at the Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB, UMR CNRS 6302) will provide new tetrahydroxamic ligands. The protonation constants of these ligands will be also determined by affinity capillary electrophoresis.
This project is performed in close collaboration with ICMUB (synthesis of new ligands), IRSN (speciation in environment, design and testing of sensors).
Funding category: Contrat doctoral
PHD title: Doctorat de Chimie
PHD Country: France
EURAXESS offer ID: 509199
Posting organisation offer ID: 91073
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