Avaliação da concentração de metais em peixes de diferentes níveis tróficos ocorrentes no Rio das Antas e no Rio Tega - RS

Abstract

The release of heavy metals into the aquatic environment causes a number of problems for this ecosystem particularly in regard to bioaccumulation and biomagnification in the trophic chain. In this context, the aim of this study was to analyze the concentration of lead (Pb), copper (Cu), chromium (Cr), mercury (Hg), nickel (Ni) and zinc (Zn) metals in the muscle tissue of native fish. of theTega and Antas rivers. The influence of the Tega River on the Antas River in relation to the concentration of metals in fish was evaluated due to the potential contamination by metal-mechanic industries installed in the contribution basin. The metals were also evaluated in relation to the trophic position of the target fish (Astyanax sp, Rhandia quelem, Loricariichtys anus, Hemiancistrus punctulatus, Hypostomus commersoni). Metal analysis was performed by inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed a high level of chromium concentration in all collected individuals, showing the contamination of the aquatic biota and risks to the consuming population of these species. Zinc concentration was high only in the Tega River lambaris (Astyanax sp) samples. Copper and nickel levels are below the limits established by the Ministry of Health, through Anvisa's RDC No. 42/2013 and Decree 55871/65, in all samples analyzed, while mercury and lead did not reach the detection limits of the equipment. Because they are metal compounds with cumulative capacity, they can affect human health when fish are consumed. Analysis detected the presence of copper and nickel in muscle tissue. However, mercury and lead were not found in these tissues. It was also evidenced that the chromium metal presented bioaccumulation in detritivorous individuals of the Antas and Tega Rivers, presenting similar concentrations. Copper and nickel metals did not show significant concentration differences in comparison with the target species. Zinc presented different concentrations in omnivorous individuals from the Antas River. In the Tega River, the copper, nickel and zinc metals showed significantvalues only for omnivores, showing greater bioaccumulation of these metals in these individuals.