Concentration of metals in the Doce river in Mariana, Minas Gerais, Brazil

Abstract

This research evaluated the concentrations of metals of Doce River water after the rupture of Fundão Dam, located at Bento Rodrigues District, in Mariana City, Minas Gerais, Brazil. Water samples were collected at a source upstream of the rupture site (P1), upstream of a containment embankment of the dumped sludge (P2) and downstream of the containment embankment (P3). Concentrations of lead (Pb), arsenic (As), nickel (Ni), copper (Cu), aluminum (Al) and manganese (Mn) in the samples were determined by spectrophotometry. The highest concentrations were observed at point P2, the concentrations found were (em mg L-1): Pb (0,097); As (0,911)1; Ni (1,078); Cu (1,115); Al (9,432) e Mn (1,638), and copper concentration, at this point, was 86 times higher than the maximum permissible value (MPV) by Brazilian legislation, for Class III water quality . At point P1, concentrations of Ni (0.051 mg L-1), Cu (0.062 mg L-1) and Al (0.465 mg L-1) were 2.0; 4.8 and 2.3 times greater than MPVs, respectively, and these results can be related to the local mineralogy. The high concentrations of these metals in river water are related to the environmental disaster of Mariana, Minas Gerais, with mine tailings. Environmental policy actions and area recovery are essential for rebalancing the chemical characteristics of this aquatic ecosystem.