Waterborne nickel bioaccumulation in Gammarus pulex: comparison of mechanistic models and influence of water cationic composition
Bioaccumulation du Ni par voie dissoute chez Gammarus pulex : comparaison de modèles et influence de la composition cationique de l'eau
Résumé
The biodynamic and saturation models offer promising lines of enquiry to predict the bioaccumulation of metals by aquatic organisms. However, in order to construct these models, the accumulation strategies have to be defined for each metal/organism couple in controlled conditions. This study aims at modelling the waterborne bioaccumulation of Ni and the influence of the water's geochemical properties on this process in a crustacean that is widely distributed in Europe, Gammarus pulex. In the laboratory, G. pulex was exposed to several Ni concentrations (from 0.001 to 100 mg L−1) in aquatic microcosms. Our results show that G. pulex is very tolerant to Ni (LC5048 h = 477 mg L−1 Ni). Time course experiments enabled the construction of a biodynamic model by determining the uptake (ku) and elimination (ke) rate constants. When the exposure concentration exceeded 1 mg L−1 Ni, the metal uptake reached a maximum due to a limited number of binding sites for Ni. Therefore, the organism's maximal capacity to accumulate the metal (Bmax) and the half-saturation constant (K) were determined to establish the saturation model. We showed that the two models are comparable for the lowest exposure concentrations (