Efeitos de metais pesados presentes na água sobre a estrutura das comunidades bentônicas do alto Rio das Velhas

Abstract

Rio das Velhas and its tributaries drain a region of high populational and industrial density in Minas Gerais State. The quality of these waters, assessed by Biotic Indexes and by the Water Quality Index (WQI), ranges from Excellent to Very bad, due to the discharge of industrial, agricultural and domestic effluents. The goal of this dissertation is to investigate, using results of physicochemical, bacteriological and zoobenthos analysis, the effects that the heavy metals discharged into Rio das Velhas and monitored by IGAM exert, altogether, on the communities of benthonic organisms of this river. The data used are from a historical series, from 1985 to 2004, produced by CETEC and GEOSOL, for FEAM and IGAMs monitoring programs. This research aims to identify and describe, using biotic indexes, such alterations, correlating them with the metal content and with WQI. The author has verified that the WQI keeps a positive correlation with the biotic indexes BMWP, richness, Shannon- Wiener diversity and Pielou equitability but its not sufficient to explain all its variations. A metal index, developed by the author, keeps, on the other hand, a strong negative correlationwith the above mentioned biotic indexes. The author concludes that the heavy metals discharged into Rio das Velhas and on its tributaries alter and impact the structure of benthonic macroinvertebrates.