Contamination by potentially toxic metals from urban rivers located in an area covered by the Guarani Aquifer in Southern Brazil

Abstract

The present study aimed to evaluate the concentration of heavy metals considered globally alarming, such as cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn), in the surface water and in the sediment of urban rivers located in an area covered by the Guarani Aquifer, in Lages, southern Brazil. The water and sediment samples were collected in September and October 2016 in three urban rivers. The quantification of the metals was performed through an atomic absorption spectrometer. The levels of Cd, Cr, Cu, Pb and Zn in the control points (P1 and P7) presented a concentration below the level I proposed by Brazilian legislation 344/2004 of the National Environment Council (CONAMA), while the other points presented concentrations higher and above level I, evidencing an increase of metals in the rivers from upstream to downstream of the urban area of ​​Lages. Cr concentrations above level II proposed by Brazilian legislation at the mouth of the Carahá River were also found, and this value may have adverse effects on aquatic biota. The results show that urban rivers in the area covered by the Guarani Aquifer in Lages have been contaminated by toxic elements associated with anthropogenic activities.