Avaliação da influência da mineração nas características geoquímicas do Arroio João Dias em Minas do Camaquã, RS

Abstract

Minas do Camaquã is a locality belonging to the 3rd district of the city of Caçapava do Sul, located in the south-central region of the state of Rio Grande do Sul. This location became famous for its copper mining activity, which lasted for over a century from 1865 until 1996. Arroio João Dias is a water body that has part of its course very close to the copper mining of Minas do Camaquã. In the region there is a water catchment dam and a tailings dam. The present work had as main objective, to make an environmental diagnosis of this water body through geochemical analyzes. The methodology covered physical and chemical analyzes of the surface water and river sediments of Arroio João Dias. Concerning surface water, physicochemical parameters such as temperature, pH, electrical conductivity, turbidity, total alkalinity and total hardness were raised. In addition to these parameters, the presence of heavy metals present in raw water was evaluated. In relation to river sediments, the particle size analysis, organic matter content and element content determination in the sediments were performed. The results showed that the water has neutral pH and turbidity values within natural water standards at all collection points. The alkalinity, hardness and electrical conductivity parameters showed decay at points P2 and P3, which were most affected by mining. The sediment granulometry varied between the points where, P1 and P3 had a larger distribution in each fraction, while in points P2 and P4 the sand fractions were predominant. The sediments presented very low organic matter values. In the elemental analysis, water presented higher values of Al, Fe, Cd and Cu, while in sediments the most detected metals were Al, Fe, Mn and Cu. It was concluded with this study that there was a big difference between the conditions of Arroio João Dias with the conditions of the time when the copper mine was active.