Bioacumulação e biossorção de cobre e mercúrio por Salvinia biloba Raddi (Salviniaceae)

Abstract

This study evaluated the potential for biocumulation and biosorption of copper and mercury by the aquatic macrophyte Salvinia biloba Raddi (Salviniaceae), as a function of different concentrations of copper and mercury ions in the solution, the time of exposure of the biomass to the contaminant, and different pHs, as well as identify the effects of these metals on morphological and anatomical characteristics of this species. Bioaccumulation was evaluated under concentrations of 1, 3, 5 μg.mL-1 of copper and 0.05, 0.1, 0.2 μg.mL-1 of mercury, as well as by the control treatments (0 μg.mL-1 of copper and mercury), at three-day intervals (zero, 3, 6, 9, 12 and 15 days) at pHs 5, 6, 6 and 6.5. For the biosorption the same design was used, altering the time intervals (zero, 4, 8, 12 and 24 h). The content of bioaccumulated and biosorbed mercury and copper was determined by atomic absorption spectroscopy, and for the mercury used the cold steam generation technique. The results showed high values of copper and mercury bioaccumulated and biosorbed by biomass of S. biloba. The concentration of copper and mercury in the solution showed significant effects for both bioaccumulation and biosorption. It was observed that as the concentration of these ions increases in the solution, the higher the bioaccumulated and biosorbed value of S. biloba. The exposure time of the biomass to the metals and the different pHs did not influence in isolation the bioaccumulation and the biosorption of these metals. However, for copper, the interaction between the different concentrations and pHs had joint effects on S. biloba bioaccumulation. Regarding the bioaccumulation of mercury, the interactions were significant for the exposure time and the concentrations, as well as between the different pHs and the different concentrations. Few symptoms of toxicity and anatomical and morphological variations were observed in the plants submitted to the different treatments with copper and mercury. It is evidenced that S. biloba has potential of bioaccumulation and biosorption of copper and mercury, being able to be used as phytoremediation species in natural or anthropic aquatic environments contaminated by these metals.