The Biogeochemistry, Bioavailability and Radionuclide Transfer Laboratory (LTBT) is located in Cadarache, in south-east France. Rodolphe Gilbin heads a team of ten research scientists and engineers and two technicians, and currently has four PhD students.
Context and research themes
L2BT is part of the Environmental Risk Research and Assessment Department (SERIS) and reports to the Environment Director in the Radiation Protection, Environment, Waste and Emergency Response Unit (PRP-ENV).
L2BT conducts studies and research aimed at characterising the pathways by which living organisms are exposed to pollutants induced by nuclear activities (radioactive substances and the related stable chemicals) in continental, aquatic and terrestrial ecosystems, whether in chronical or post-accidental exposure situations. This involves:
- adopting an experimental approach to understand the mechanisms involved, estimate and reduce the conceptual and parametric uncertainties in models describing the transfer of pollutants to ecosystems, bioavailability and, ultimately, exposure of organisms;
- working on phenomenological models and operational tools for predicting exposure and contamination of organisms;
- testing models, operational tools and knowledge acquired in the laboratory for their representativeness, through comparison with in situ observations (e.g. Chernobyl exclusion zones, former uranium mines in France, contaminated area around Fukushima).
This working method is implemented in collaboration with other IRSN teams and various partners both (i) in the ecotoxicology field, to gain more insight into cause (exposure) and effect (ecotoxic response) relationships, thereby allowing the use of less conservative risk indices and protection criteria for ecosystems; and (ii) in the radioecology field, by integrating the dynamics of exchange processes at the interfaces between environmental compartments (water, air, soil, sediments, organisms) and, on a greater temporal and spatial scale, for estimating dosimetric impact.
L2BT adopts an interdisciplinary approach to research projects in two of IRSN's main research programme areas. The goal is to identify and understand the physical, chemical and biological mechanisms governing the exposure dynamics of organisms, on different time scales, to pollutants related to nuclear activities. This is achieved by studying:
- the biogeochemical behaviour (speciation, reactivity, transformation) and transfers (mobility, retention) of these pollutants in, and between, terrestrial and continental aquatic ecosystem compartments (soils, sediments, water, air, living organisms);
- bioavailability processes, bioaccumulation and elimination pathways, and internal distribution, up to the identification of the targets (organ, cell, molecule) of these pollutants in aquatic and terrestrial plants and animals, taking into account specific biological (molecular interactions, metabolism, physiology) and ecological factors (habitat, trophic relationships).
The main on-going research projects are as follows:
Radionuclide transfer in environmental compartments (soil, water, sediment)
- Understanding reactive and non-reactive transfer/transport mechanisms in the unsaturated soil zone – alternative approaches to the distribution coefficient (Kd) for modelling (e.g. Cs, Sr, Se, U);
- Creating a database for implementing Equilibrium-Kinetics models.
Activity levels and transfers in the terrestrial biosphere
- Radionuclide reactivity with respect to soils and root availability: in situ/laboratory approaches and modelling;
- Radionuclide transfer to plants through the leaves;
- Radionuclide transfer and recycling in forest environments (Cs, I, Se, Cl) and impact of the soil organic mater cycle on radionuclide transfer;
- Leaching and transport of soil contamination to hydrosystems through erosion and runoff (e.g. Cs at Chernobyl and Fukushima).
Bioavailability, bioaccumulation and internal distribution in organisms
- Radionuclide interactions (Cs, U, Sr) and bacterial communities in soils (Chernobyl);
- Identification of root uptake mechanisms and radionuclide (U, Cs, Co) membrane transport mechanisms in plants (Arabidopsis, rice);
- Fate of radionuclides (Cs, U, Sr) at the soil-root interface and impact of their uptake on higher plants;
- Bioaccumulation of radionuclides by direct and trophic pathways and distribution in aquatic organisms. Determination of internal toxic concentrations;
- Uranium speciation in aquatic organisms: Analytical developments for the identification of the biological ligands involved in sequestration/detoxification,and the explication of toxic effects.
Multiple stressors and interaction processes between contaminants (stable metals, organic substances, radioactive substances)
- Integrated methodological development (exposure, effect and risk) under multiple contamination conditions (bioavailability modulation, additivity models, incorporation within a DEBTox approach and to ecological risk assessment).
- Ecosystem protection criteria and ecological monitoring tools
- Determination of a PNECwater for uranium dependent on physical-chemical conditions;
- DGT performance study to characterise the exposure of aquatic organisms to uranium;
- Use of otoliths as an integrated marker of fish exposure to uranium during their whole lifespan.
Specialties and researchers
Researchers and engineers
Frédéric Coppin (researcher in biogeochemistry)
Laureline Février (researcher in biogeochemistry; STAR NoE coordinator assistant)
Sandrine Frelon (researcher in speciation and radionuclide metrology)
Laurent Garcia-Sanchez (researcher in n radioecology, statistics and probabilities)
Rodolphe Gilbin (researcher in aquatic ecotoxicology, head of laboratory)
Pascale Henner (researcher in radioecology, plant physiology)
Pierre Hurtevent (researcher in radioecology, terrestrial ecosystems)
Arnaud Martin-Garin (researcher in biogeochemistry, deputy head of laboratory)
Daniel Orjollet (engineer in radioactive metrology)
Olivier Simon (researcher in aquatic ecotoxicology)
Sylvie Pierrisnard (technician in chemistry)
Danielle Poncet-Bonnard (technician in radioactive metrology)
Adrien Margerit (06/02/2012-05/02/2015)
Yvan Eb-Levadoux (01/03/2014-01/03/2017)
Laure Geniès (07/10/2013-06/10/2016)
Amine Cherif (02/12/2013-01/12/2016)
Facilities and techniques
L2BT uses the ECORITME platform for research into the ecotoxicological effects of ionising radiation and trace metals.
Partnership and research networks
As well as working on IRSN's own research programmes, L2BT carries out research for or in partnership with various national or international organisations (European projects). Examples include:
- Partnerships with major stakeholders in the French nuclear sector (CEA, EDF, ANDRA);
- Partnerships with leading French research institutions (Ineris, INRA) and universities (Marseille, Toulon, Montpellier, Bordeaux, Pau, Toulon, Grenoble);
- STAR network of excellence and the European Radioecology Alliance;
- Collaboration with local research teams in Ukraine (UIAR, IGS, SSRI) and Japan (University of Tsukuba).