Interaction of Radionuclides (U, Ra) with Diatoms
Dr. Susanne Sachs (HZDR), Dr. Gilles Montavon (Subatech), Dr. Olivier Peron (Subatech)
The thesis subject is related to the activities at the Zone Atelier Territoire Uranifère (ZATU) and here in particular associated with the structuring projects TERROIR (Transfer/tRanspOrt of (radio)elements and their Impact/risk on the environment of the Rophin site) and Tiramisu (BiodiversiTy In RAdioactive MIneral SoUrces). One of the objectives of these structuring projects is to evaluate the effect of low doses caused by naturally occurring radionuclides (RNs) on model aquatic microorganisms such as diatoms at the ZATU instrumented site (former Rophin mine) and its observatories (i.e. radioactive mineral springs).
Diatoms are microorganisms sensitive to pollution. Initial results obtained in radioactive mineral sources indicate deformations of frustules (F. Millan et al. 2020). This thesis topic is complementary to two parallel thesis projects, sharing together a general aim of comparing biological, physico-chemical and radiological data in a way to identify the main abiotic drivers and to differentiate between the impact of radiation and chemical toxicity due to radioelements or some other effects (nitrates, heavy metals…) on the diatom’s life.
The work conducted at HZDR focus on the determination of the U speciation and localization in the presence of diatoms. Various analytic (ICP-MS), spectroscopic (TRLFS, FTIR) and microscopic (SEM/EDX, TEM) techniques are practiced in order to collect information at the microscopic/molecular scale, which will contribute to a mechanistic process understanding for the interaction between U and diatoms.
The work at HZDR is partially supported by ALLIANCE funding.
F. Millan, et al. (2020), The effect of natural radioactivity on diatom communities in mineral springs, Botany Letters, 167(1), 95-113.