Fitorremediação de ambiente aquático contaminado por atividades antrópicas em Pelotas/RS

Abstract

Anthropogenic activities are responsible for the disturbance of natural and urban ecosystems, and among them, the most impacted are the aquatic environments. An alternative to recover these areas is phytoremediation, a technology that uses plants as the main decontamination agents. The aquatic macrophytes are plants that have the capacity to remove different compounds, and, therefore, the aim was to evaluate in different studies the in situ phytoremediation potential of Hydrocotyle ranunculoides, Enydra anagallis and Sagittaria montevidensis, macrophytes species of Santa Bárbara Stream, Pelotas/RS. First, the concentration of nutrients and heavy metals in Santa Bárbara stream was determined by digestion in nitric and perchloric acid and quantification in ICP-OES and a Pearson correlation analysis, factorial analysis and principal components were performed to identify the probable sources of contaminants thus constituting the initial study (Paper 1). Agricultural activities, the atmospheric deposition of vehicular emissions and the release of domestic and industrial effluents as the possible sources of contaminants were pointed out. Subsequently, each species of plant (H. ranunculoides, E. anagallis and S. montevidensis) was analysed individually, constituting the Paper 2, 3 and 4, respectively. The analysis of the concentration of the elements in the roots and shoots of the plants was performed by digestion in nitric and perchloric acid and quantification in ICP-OES and phytoremediation indexes were calculated (bioconcentration factor, translocation factor, plants effective number and phytoremediation potential). The results allowed to detect potential for the removal of heavy metals and nutrients by the three species studied and, in general, the most appropriate techniques to be applied are phytoextraction and rhizofiltration, considering the ability of plants to accumulate the elements of the environment and translocate to the shoots; and to filter the elements and maintain the highest contents in their roots, respectively. H. ranunculoides was highlighted by the phytoextraction potential, among other elements, of phosphorus and arsenic, and rhizofiltration of copper, cadmium, chromium, nickel, lead, and vanadium. E. anagallis was identified as having phytoextraction potential of cadmium and phosphorus and the potential of rhizofiltration, among others, of chromium, copper, lead and vanadium. S. montevidensis demonstrated the ability to filter, among other elements, vanadium, arsenic, copper, lead and cadmium. Thus, it is highlighted the importance of these species in removing the contaminants and the possibility of use in the recovery of other water bodies affected by anthropogenic activities.