Effect of artesanal gold mine activities on metals and metalloids contents in soils and sediments from apolobamba, Bolivia

© 2016 Nova Science Publishers, Inc. Artisanal and small-scale gold mining activities in Apolobamba area, northwest of La Paz, Bolivia, may produce serious environmental concern and great risk to human health. The current methods used to extract gold through the amalgamation process result in metal contamination of soil and water, as well as a negative effect on health of miners and inhabitants. Two main sources of contamination has been identified, the large amount of Hg used for gold extraction and the arsenic in the arsenopyrite from gold ores; also other metals, such as Zn, Pb, Cu and Cd, are associated to mining operations and may contribute to environmental pollution. The objectives of this work were to characterize the contamination of Hg, As, Cu, Cd, Pb and Zn in soils and sediments, and to assess the risk to human health and environment in different cooperatives mines in the highlands of Bolivia. In order to achieve these objectives, soils and sediments samples were collected, and physicalchemical properties and Hg, As, Pb, Cu, Zn and Cd analysed. Results showed that As and Hg concentrations were higher in top soils than in subsurface soils in the Sunchulli-Viscachani area, indicating active As/Hg atmospheric deposition, whose concentrations exceeded the soil Hg and As threshold levels. Oppositelly, concentrations of Cd and Zn largely exceed the thresholds levels in Katantika and Sural mining districts. These data indicated that a potential risk for human and environment could be taking place. In addition, Sunchullí and Viscachani lake sediments were contaminated by Hg, As, Cd, Zn and Cu, while Katantica lake showed high concentrations of Zn, Cd and Hg, and in the Sural lake were reported high levels of As, Zn and Cu. Results showed that Cu, Pb, As and Hg concentrations in sediments from the Sunchulli River; As, Hg and Cu in the Pelechuco River, and As and Hg in the Rayo Rojo River come from mine direct discharges into the rivers. These concentrations may cause a serious problem for aquatic life, related ecosystems and human health. Therefore, there is a need to study metals and metalloids availability and speciation in soils and sediments to better understand the cycling of these elements and transfer of metals/metalloids from soils into the food chain in the area.