Impacto ambiental en los recursos naturales de una zona afectada por la actividad minera en Boliviaevaluación geoquímica de suelos y sedimentos

Résumé

The current methods used in Bolivia to extract gold using the amalgamation process with mercury result in environmental contamination and a risk to human health. The objective of this study was to determine Hg, As, Cu, Cd, Pb and Zn concentrations in soils and sediments from three mining districts. Results showed As and Hg concentrations were higher in the topsoil than in the sub-surface soils in the Sunchullí-Viscachani area, indicating active As/Hg atmospheric deposition, where concentrations exceeded the threshold levels. In addition, concentrations of Cd and Zn largely exceeded the threshold levels in the Katantica and Sural mining districts. In addition, the Sunchullí and Viscachani lagoon sediments were contaminated by Hg, As, Cd, Zn and Cu, whilst Katantica lagoon showed high concentrations of Zn, Cd and Hg, and high levels of As, Zn and Cu were reported in the Sural lagoon. Our results showed that the Cu, Pb, As and Hg concentrations in sediments in the Sunchullí river; As, Hg and Cu in the Pelechuco river, and As and Hg in the Rayo Rojo river all come from direct mine discharges into the rivers. These high concentrations of metals and metalloids must cause an impact on the aquatic ecosystems and human health. Therefore, there is a need to study the availability and speciation of metals and metalloids in soils and sediments to better understand the cycling of these elements and their transfer to the food chain.