Potentially toxic metal environmental pollution in sediments of a model hydroelectric plant water reservoir in Brazil

The main electric energy source in Brazil comes from hydroelectric plants, which involve the construction of large water reservoirs. The Brazilian center-west region occupies 25% of the national territory, with the Cerrado (native tropical savanna) as predominant biome. This region has many hydroelectric plants, in addition to agriculture and livestock. It has resulted at sediment inputs containing pesticides and heavy metals into water reservoirs, affecting plants and animals. The aim of this work was to evaluate the heavy metal environmental pollution indices in sediments of a model hydroelectric plant water reservoir located in the center-west region of Brazil. The sediment samples were prepared using acidic digestion in microwave oven for the determination of the metal concentrations by inductively coupled plasma optical emission spectrometry (ICP-OES). The cadmium (Cd), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) concentrations in sediments of the model water reservoir were compared with maximum limits stipulated by the Conama Resolution n. 454/2012. Moreover, the geoaccumulation indice (Igeo) and contamination indice (CI) were determined. According to Igeo values, the water reservoir direct influence area was classified from moderately to extremely polluted due to high metal concentrations in the study sediments. From CI values was concluded that the environmental pollution indice varied from moderate to high, corroborating the Igeo classification.