The Ribeira de Iguape River, one of the most important rivers in the Brazilian southeastern state of São Paulo, has sources in the Paraná state, drains from Northwest to Southeast between São Paulo and Paraná states through the Ribeira Valley and reaches the Atlantic Ocean at Iguape, in the Southern coast of the first state. During almost the entire 20th century, the Ribeira de Iguape River experienced intense activity related to mining (gold and lead-silver mining). As consequence, it is estimated that the Ribeira de Iguape River received the discharges of residues rich in As, Cd Pb, Cu and Zn, for approximately 40 years. In many studies carried out during the mining and ore processing period, around 1980 decade and the beginning of the 1990 decade, were ascertained high concentrations of Pb in water and sediments of the Ribeira de Iguape River, in their influent rivers and Cananéia-Iguape Estuarine Complex. More recently, studies have demonstrated that the concentrations of metals in sediments and waters from Ribeira de Iguape River have been decreasing. However, studies found that bioaccumulation of metals in Ribeira de Iguape River bivalves still remains, suggesting that such organisms may transfer metals through the biological web, so risks could persist to the biota associated to this river. In this study samples of bottom sediments will collect at five sampling sites distributed along the river, with the purpose of evaluating the environmental quality (availability and toxicity of Pb, Cd, Cr, Zn and Cu in bottom sediments).
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