Dissolved and particulate metals in Mirim Lagoon, Brazil-Uruguayan border

Abstract

Mirim Lagoon is shared between Brazil and Uruguay. It benefits an approximate population of 1 million people and supplies the Taim wetlands (Biosphere Reserve-UNESCO) with water. In spite of having unusual features, such as a large size, its localization near an international border and its ecological and economic importance, Mirim Lagoon has been scarcely studied. The present work thus has as its goal to assess its hydric quality, through dissolved (Cu, Cr, Zn, Pb, Ni, Cd, Fe, Mn, Al, Hg e As) and particulate metal concentrations (Cu, Cr, Zn, Pb, Ni, Cd, Fe, Mn e Al), as well as to discuss the use of iron and aluminium as geochemical normalizers. Natural processes such as meteorological and hydrodynamical events presented a direct influence upon dissolved and particulate metal concentrations, surpassing that of anthropic origin. Iron was the main geochemical carrier in the suspended matter, being more indicated as a geochemical normalizer than aluminium. Mirim Lagoon can be considered to be little impacted regarding metal concentrations, except for zinc and cadmium, emphasizing the need for further investigation.