Is it relevant to take into account the multipollution context in freshwater radioecology ?

Abstract

Abstract. Should realism of radioecological evaluations be enhanced while taking into account the deleterious influence of stable pollutants on aquatic organisms which can be physiologically stressed, and therefore can modify their response to radionuclide bioaccumulation? Transfer experiments in a multipollution context involved metals {Cd, Zn), organic pollutants (PCBs, PAHs, oestrogenomimetics) and radionuclides (radioactive isotopes of Co, Cs, and Ag). The chosen biological models were a freshwater bivalve (Dreissena polymorpka) and a carnivorous fish (Oncorhynchus mykiss). Chronic metallic waterborne exposures (1-4 ng/L Cd and/or 170-250 ug/L Zn) led to a decrease in radionuclide bioaccumulation with respect to the reference group (Ag and Cs for fish with respectively -60% and -30%; Co for bivalve with -50%, on average); while no effect was noticed with other radionuclide/organism pairs (Co for fish, Cs and Ag for bivalve). Prior exposure to organic micropoltutants enhanced I7 Co and 1 Cs uptake kinetic parameters from water and retention time in fish; the radionuclide contamination levels of exposed groups were always higher than those obtained from the reference groups (-1-10% to +60% as a function of the organic micropoUutant). Some explanations are given for these first results that underline the relevancy of this new research field.

Assessing ecological effects of radionuclides: data gaps and extrapolation issues

“…The relevance of considering the influence of multipollution in radioecological assessment models has been proved various examples. Among others, laboratory transfer experiments in a multipollution context have shown that chronic metallic waterborne exposures (1-4 µg l −1 Cd and/or 170-250 µg l −1 Zn) led to a decrease in radionuclide bioaccumulation with respect to the reference group (uptakes of Ag and Cs in fish reduced by 60% and 30%, respectively; uptake of Co in bivalves reduced by 50%, on average); whereas no effect was found with other radionuclide/organism pairs (Co for fish, Cs and Ag for bivalves) [28]. Prior exposure to organic micropollutants enhanced 57 Co and 134 Cs uptake kinetic parameters from water and retention time in fish; the radionuclide contamination levels of exposed groups were always higher than those obtained from the reference groups (+10% to +60% as a function of the organic micropollutant) [29].…”