Geoquímica de metais e metaloides em área de garimpos de ouro na Amazônia paraense.

Abstract

The Amazon is an important source of natural resources, rich in biodiversity, water resources and minerals, provides ecological services important to the world, such as storing fresh water and minimizing the effects of global warming. Therefore, studies that demonstrate the dynamics of potentially toxic elements (EPTs), such as metals and metalloids, in soil are of great relevance. The identification of the concentrations of these elements is indispensable for control and decision making in order to avoid environmental impacts and the health of plants and animals, including humans. The concentration of EPTs in Cachoeira do Piriá on soil samples under native forest and tailings of different types of gold exploration (Au), as well as chemical and granulometric attributes, and their relationships with EPTs were determined. In order to evaluate the degree of pollution, the enrichment factor (FE), contamination factor (FC), geoaccumulation index (Igeo), pollution load index (PLI), potential ecological risk (REP) and ecological risk multi-element combination (IR). High levels of EPTs were found in the rejects of the Au exploration areas, values higher than those of research (VI), defined by CONAMA, which characterizes polluted areas. The concentrations of As, Co, Cr, Ni, and Sb of the 18 elements evaluated only Ag, Cd and Si are at levels corresponding to the natural values, that is, soil quality reference values (VRQs) for the state of Pará. The concentration of As, Co, Cr, Ni e Sb are above VI while Hg and Mn are above the prevention values (VP) defined by CONAMA and above the world average. There was enrichment of the EPTs As, Ni, Sb, Ag and Mo. All the elements presented moderate to highly contaminated CF in at least one of the gold mines, demonstrating contamination by EPTs. The PLI indicated soil deterioration in all gold mines as well as extremely high RI for a large number of EPTs. From the pollution indexes determined for the areas of artisanal mining we can infer the need for immediate actions for remediation and reduce the environmental risks and the health of the local population.