Determinação dos metais Cr, Cu, Fe, Mn, Ni, Pb e Zn em solo de Paracatu de Baixo - subdistrito de Mariana, MG 8 anos após rompimento da Barragem de Fundão

Abstract

On November 5, 2015, in the municipality of Mariana, MG, the Fundão dam, which stored waste from iron ore processing, ruptured, releasing approximately 34 million m³ of ore tailing into the environment. Among the areas affected by the mud is the subdistrict of Paracatu de Baixo, which belongs to the territory of Mariana. Considering that, even after partial destruction of the location, some residents still reside there, the main goal of this study were to verify the existence and concentration of ecotoxic metals (Cu, Cr, Zn, Pb, Fe, Mn and Ni) in areas affected by the waste, through analysis of differences between the concentrations found for these elements and the values allowed by legislation. The methodology used to develop this work is characterized as exploratory descriptive. Six soil collections were carried out at a depth of 20cm, 4 collections in areas affected by waste and 2 in non-impacted areas. Each collection point consisted of 5 subsamples. The subsamples from each point were subsequently homogenized and 50g from each sampled point were sent for analysis at the Laboratório de Química Instrumental do Instituto de Ciências Agrárias from Universidade Federal de Minas Gerais (LQI-ICA-UFMG) on the regional campus of Montes Claros, MG. Quantifications of the metals: Pb, Cu, Cr, Ni Fe, Mn and Zn were carried out in a Varian Atomic Absorption Spectrophotometer (AAS 240 FS) in flame mode. The results showed that, 8 years after the dam collapse, iron and manganese still occur in all collection areas and present the highest values among the metals analyzed. The concentration of these metals is significantly higher in areas impacted by waste than in unaffected areas. Chromium, nickel and copper had no quantified values at any of the collection points. Of the areas analyzed, only two did not show the presence of lead metal, both were contaminated by waste and zinc was present in all areas collected, with no significant relationship in concentration with impacted areas or not. All metals evaluated presented concentrations lower than the Quality Reference Values (VQRs) recommended by Deliberação Normativa COPAM 166/2011, with the exception of iron and manganese metals, which do not have reference values in this deliberation.