QUANTIFICAÇÃO DE CONTAMINANTES METÁLICOS EM ESPÉCIES BIOINDICADORAS COMO FERRAMENTA EM ESTUDOS DE IMPACTO AMBIENTAL

Abstract

Several studies of metal contamination in aquatic environments have been made in recent years focusing on the use of biological indicators. The importance of trace metals varies according to their need for human life. The oxidation state (III) for chromium is beneficial in small quantities, participating in the metabolism of the human body, but in the oxidation state (VI) has carcinogenic. Lead is of great environmental interest, because it is present in considerable urban concentrations. The sources of contamination of these metals in aquatic environments can come from industrial waste such as: plating, printing, tannery and pigments. The study to evaluate the environmental pollution can be accomplished through biological indicators such as fish and plants, because the same suffer bioaccumulation and biomagnification of metals. The studied enviment in this work, stream of Guarapuava city PR, receives unhandled sewage load of tanning to more than thirty years. In previous studies conducted by the Group of Trace Analysis and Instrumentation (GATI) were determined high levels of chromium in the particulate for the same environment. Therefore, the aim of this study was to evaluate the level of pollution present in that stream through the quantification of Cr and Pb in plants and fish. The work consisted in the optimization of the analytical methodology used in the sample preparing and quantification technique. Fish and plants were prepared by wet acid digestion. The technique used for the quantification of metals was the anodic and cathodic stripping voltammetry with differential pulse polarography. Biological indicators collected from sources free of contamination were also evaluated to obtain a pattern of local background. The comparison of the values obtained with samples of the studied and pattern background was important to confirm the pollution in the stream due to the excessive discharge of industrial effluent. These discharges represent a risk to the balance of aquatic communities.