Distribution of Heavy Metals in Environmental Samples Near Smelters and Mining Areas in Brazil

Abstract

The State of Minas Gerais possesses one of Brazil's important smelting resources. Aquatic contamination produced from mining activities and smelting of ores in the region may be harmful to the human population. However, no studies on levels of heavy metal have been carried out in the area. Thus, to assess the extent of pollution resulting from the metalliferous industry, river water, sediment, plant and fish samples were collected up- and down-river from the smelters and mining areas in Conselheiro Lafaiete and Ouro Branco and analysed to detect metal inputs. Samples of mineralized, contaminated and non-contaminated regions were also collected in the State of Minas Gerais to obtain control values. The metals examined included Fe, Al, Mn, Pb, Cu, Zn, Co, Cd, Ni, and Cr and were selected due to their toxicity and occurence in ores. Metal inputs in the samples analysed appeared to be related to effluent discharges into the rivers. High concentrations (in µg l−1) of Mn (697), Pb (153) and Cd (12.7) were found in river water collected from the smelting region when compared with control areas. The river sediments showed high concentrations (in µg g−1) of Mn (32276), Cd (1.4), Cu (70.6), Ni (170), and Cr (174). The concentrations of Mn and Cr in the plants were higher than those normally found in these materials. Chromium concentration in fish was found to be five times higher than the Brazilian recommended value for human intake.