Mechanistic and ecophysiological study of carbon 14 transfer in fish
Résumé
Carbon-14 (14C) is one of the two radionuclides which are released in greatest amounts into rivers by the nuclear power plants in routine operation. In France, 14C contributes to a major fraction of the estimated annual dose absorbed by local populations living in the vicinity of nuclearized rivers, mainly by ingestion of radiocontaminated fish. However, mathematical models used to assess the transfer of 14C to the aquatic ecosystems are unable to explain 14C values observed in sampled fish. One of the reason for this is that these models are very simplistic, neglecting the potential influence of changes in 14C speciation, biochemical transformations occurring along trophic chains and the potential influence of fish physiology as a function of environmental factors, such as temperature or food. In this context, the present PhD project aims to adapt the conceptual approach known as the “Dynamic Isotope Budget” (DIB), an extension of the Dynamic Energetic Budget (DEB) used to describe stable isotope fluxes in organisms, to the case of 14C transfers among water, sediment, phytoplankton, zooplankton, and fish. In this aim, Cyprinus carpio is selected as a robust laboratory species, commonly found during radioecological monitoring in French rivers and available in the Add-My-Pet collection.
First, a literature search is conducted and size and reproduction data are used to improve the parameterization of the DEB model for C. carpio. Second, sensitivity analyses (MORRIS, SOBOL’) are carried out to identify most influent parameters. Finally, on-going experiments are conducted to quantify transfer efficiencies of 14C in different processes of the DIB model using different forms of 14C (glycerol, arginine, glucose, as precursors in lipid, protein and glucid metabolims).
Domaines
Sciences de l'environnement
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