Estudo da ocorrência de arsênio, cobre, chumbo e zinco em drenagens na área da mina Cerro Rico em Lavras do Sul – RS - Brasil

Abstract

A mining is a basic activity in the world economy, and in Lavras do Sul the activity has been present since century XVIII. However, as exploration and processing of gold, generated many wastes, many of them toxic. How the region was a intense mining area for a while, the risks of contaminated the water by heavy metals, it became necessary research about that, taking into account the well-being of the population and environmental integrity. That way, were made analysis to determinate the presence and concentration of lead, copper, zinc and arsenic for the fact that’s elements are toxic in the aquatic environments, and their direct relationship with gold mining activities, in the springs and sediments in the Cerro Rico, for this was used the Inductively Coupled Plasma Atomic Emission Spectrometry (ICP OES). In addition, physical and chemical tests were performed to categorize the quality of the waters. The data obtained by the analysis are treated by a computer simulation, for relevant reactions to the environment, using the Phreeqc software. That’s results indicated that total alkalinity and a Biochemical Oxygen Demand (BOD) presented inadequate results for a water class (3) analyzed. All the results were compared to the limits established by FEPAM and CONAMA. Were detected the presence of Pb, Cu, Zn and As in the water samples, mainly represented, by species H2AsO4-, HAsO42-, Cu2+, Cu+, CuOH+, Pb2+, PbOH+, Zn2+ and ZnOH+, which present in concentrations classified chemically how subsaturated, except for CuOH+. However, only copper has exceeded the limits set by legislation. The sediment analysis showed the presence and concentrations above the reference values adopted by FEPAM, for copper, for lead and for zinc, while arsenic was not detected by the method used. The largest accumulations were of copper, followed by lead and zinc. Concludes that the verify area around the Cerro Rico’s mine is contaminated, by copper, lead and zinc, and that these are present in the environment, mostly, on the sediments.