Etude expérimentale de la bioaccumulation et du relargage du zinc chez Dreissena polymorpha (bivalve d'eau douce) : cinétique et mécanisme de contamination et de décontamination

Abstract : In Dreissena polymorpha, the LC5028d of zinc (oligo-element) is 10,9 ppm. This metal is bioaccumulated but showed little toxicity. Contamination and decontamination dynamism varies with seasons. Zinc exposure is followed by adsorption to the shell, and by adsorption and absorption in the soft part of the mussel. Analysis of the kinetic of absorption showed an exponential and diphasic process in spring, linear in winter, and very limited and triphasic in automn (saturating kinetic). Comparison of the concentration factors of different compartments, allows to establish the following organotropism/ Byssus, mantle, gills, soft part, "rest of soft part". Rate of decontamination was found very feeble in spring. In contrast, it is much more important in automn and winter. The biological half life as determined in automn is 29,5 days. The effects of biotics factors (seasons and food) and abiotics factors (EDTA, tempe rature and lead) on zinc uptake and depuration show a big ecotoxicological complexity due several interactions between these factors, zinc concentrations in the medium and exposure time. External factors produce some modification on the physico-chemistry, kinetic and ecotoxicological aspects of metallic contamination and/or decontamination. Analysis by differencial impulsion polarography made evidence of the presence of metallothionein-like proteins (PTS : sulfurated thermoresistent proteins) in both control and zinc exposed animals. PTS concentrations are about 300mg/kg weight. Exposure to zinc doesn't lead to any quantitative modification of PTS content in Dreissena. Dreissena may be used as bioindicator of metallic contamination of the freshwaters, with the best accuracy in spring
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Abdelmalek Maarouf. Etude expérimentale de la bioaccumulation et du relargage du zinc chez Dreissena polymorpha (bivalve d'eau douce) : cinétique et mécanisme de contamination et de décontamination. Ecologie, Environnement. Université Paul Verlaine - Metz, 1988. Français. ⟨NNT : 1988METZ016S⟩. ⟨tel-01775758⟩

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