Contribution to freshwater hydro systems multi pollution study: experimental study of metallic and organic micro-pollutants on radionuclides bioaccumulation by fish

The influence of some metallic (cadmium, zinc) and organic (17 β-oestradiol, atrazine, polychlorinated biphenyls, polycyclic aromatic hydrocarbons) pollutants on artificial radionuclide (110mAg, 134Cs 57Co) bioaccumulation characteristics by rainbow trout (Oncorhynchus mykiss) has been tested. The basic hypothesis of this work assume that the organisms' exposure to pollutants induces mechanisms of response which could modify radionuclides bioaccumulation characteristics. During the experiments, some biological and biochemical (bio-markers) analyses were performed in order to characterize the nature and the intensity of induced stress in the organisms. These experiments were performed in field and in laboratory. The results show that a cadmium and zinc exposure leads to the induction of systems against oxidative stress or systems implied in metal sequestration. It also leads to a strong reduction of 110mAg (- 60 %) and 134Cs (- 33 %) bioaccumulation. No effect has been observed on 57Co bioaccumulation. For all tested organic compounds except for fluoranthene, exposure leads to an increase of radioactive caesium ( + 10 to 45 %) and cobalt (+ 30 to 60 %) quantities bio-accumulated by rainbow trout. Only 17 β-oestradiol exposure leads to an increase of 110mAg uptake by rainbow trout. Some hypothesis concerning the involved mechanisms are proposed, and the main implications of this work in operational radioecology are discussed. (author)