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(M/EH119) Transformations and transfer of inorganic mercury and tributyl-Sn in a model aquatic ecosystem. Tessier, Emmanuel1, Rodriguez Martin-Doimeadios, Rosa1,2, Amouroux, David1, Morin, Anne3, Thybaud, Eric3, Vindimian, Eric3, Donard, Olivier1, 1 2 3 ABSTRACT- The use of model ecosystems allows understanding in more simple way the natural mechanisms involved in the distribution and transformations of metallic contaminants in the different compartments and their interactions with the biota. Laboratory incubations in microcosms (aquarium) were performed as freshwater model ecosystems to investigate the fate of inorganic mercury and tributyltin at various spiked concentrations. Mercury and tin distribution and speciation in the different compartments of the microcosms (water, sediment, biota) were investigated during a two-month experimental period. Speciation analysis was performed using ultra-trace hyphenated techniques such as gas chromatography followed by atomic fluorescence spectrometry or inductively coupled plasma mass spectrometry. The principal results obtained have evidenced different biogeochemical pathways for inorganic mercury and tributyltin during these experiments, including biotic and abiotic transformation and transfer to the biota. This suggest that our model ecosystems are fully relevant to study mercury and tin chemical cycle when compared to previous model or field investigations. Finally, preliminary incubation experiments using isotopically labeled mercury species are carried out to demonstrate the potentiality of these molecular probes to investigate environmental metallic chemistry in aquatic ecosystems. Key words: Mercury, Organotin, Transformation, Bioaccumulation |
