|
(T/MF141) Dynamics of the accumulation of cadmium and mercury by the microalga Chlorella vulgaris (Chlorophyceae). OlivaTeles, Luis1, Alpendurada, Maria2, Ribeyre, Francis3, Vieira, Maria1, 1 2 3 ABSTRACT- In this study we report the results of contaminating suspensions of the microalga Chlorella vulgaris (Beijerinck), growing in synthetic freshwater, with several chemicals (CdCl2, HgCl2, CH3HgCl) at several concentrations and for different exposures times. Thus it was possible to evaluate the capacity and dynamics of accumulation of these heavy metal contaminants in C. vulgaris in culture medium that was not nutritionally enriched. In general, at each level of contamination of the toxic products used the bioconcentration factor (concentration of metal in algae / concentration of metal in medium) stabilised when the concentration of the metal in the algae was maximal. Beyond this limit, although the metal concentration in the water and in the medium had not stabilised the development was such as to maintain relatively constant the relationship between the two values, and this leads to the conclusion that in this phase, the metal concentration in the algae is in equilibrium with that in the medium. Most probably, the dilution of the metal in the algae which occurs beyond the maximum concentration of the metal is a result, not of changed equilibrium condition, but of the continued increase in the biomass of the algae in a closed environment in which there is a limited amount of contaminant. At equilibrium phase the bioconcentration factor is dependent on the nature of the heavy metal contaminant, but is relatively independent of the level of contamination of these toxic products. Key words: bioaccumulation, cadmium, mercury, Chlorella vulgaris |
