Evaluation of Heavy Metals in Waters Influenced by Mining in the Poopó and Antequera River Basins, Oruro – Bolivia

University essay from Lunds universitet/Avdelningen för Teknisk vattenresurslära

Abstract: A study of heavy metals in surface and groundwater was conducted in Poopó and Antequera River basins in Bolivia. Problems with high levels of heavy metals in waters on the Bolivian high plateau have been known for many years and are to a great extent the cause of the mining industry in the region. In this study, ten sampling sites of surface waters and twelve observation wells monitoring the groundwater were measured in September and October 2009, which is the end of the dry season. The results show that in the Poopó River, the water is mainly affected by two factors; a thermal spring and a mining processing plant with its waste deposits. The water quality upstream of these contributions is good regarding most elements. The levels of Al, As, Cd, Fe, Pb and Zn are high in Poopó River, where the arsenic concentrations are believed to be mostly of natural means originating from the thermal spring. When it comes to Cd, Pb, Ni and Zn the major input to Poopó River is acid rock drainage or the contribution from the mines close to the village. The groundwater downstream of Poopó Village is of quite poor quality, especially near a pond close to a train station. It was found to have high levels of Cd, Cu, Ni and Zn. Further out on the plains there is no anthropogenic contamination, but the concentrations of As is very high. This is due to the arsenic rich geology. In the Antequera River basin, the water quality in the river and groundwater upstream of a tailings dam is relatively good and could be used as drinking water, but only if it is treated for the high levels of arsenic. Downstream of the large mine tailings the water quality in both the surface waters and groundwater is very poor in the consideration of the heavy metals of Cd, Al, Cu, Fe, Ni and Zn. As is believed originate naturally from the arsenic rich geology.

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