Determination of Cr, Cu, Ni, Pb and Zn in the sediments of Mangueira Lagoon/RS/Brazil

Abstract

The Mangueira Lagoon is 123 km long and 7.6 km wide at its widest point, with an average depth of 2.5 m. By the fact that this lagoon is one of the youngest geological formations on Earth (only 4.5 thousand years), little is known about the geology of its sediments. This work describes the concentration of the toxic metals Cr, Cu, Ni, Pb and Zn in surface sediments samples of Mangueira Lagoon. The sediment samples were collected and underwent pseudo-acid digestion (aqua regia / perchloric acid). The extracts obtained were analyzed by atomic absorption spectroscopy in flame. Cu and Zn were detected at all points during the test. Zn is a major element, ranging from 2.5 mg kg-1 ± 0.3% to 4.1 mg kg-1 ± 2.4%, followed by Cu with values between 2.0 mg kg-1 ± 8.5% to 2.5 mg kg-1 ± 4.2%. Considering the parameters established by the CCME (Canadian Environmental Quality Guidelines), TEL (Threshold Effect Level) and PEL (Probable Effect Level), the concentrations of toxic metals found in the surface sediment were low and showed low environmental impacts. These results constitute a contribution to a better understanding of the processes that occur in the region, serving as a basis for future work.