Heavy Metal Pollution Assessment in Surface Water and Groundwater in the Ponce Enriquez Mining Area, Ecuador

Abstract

Mining activities have been carried out in the Ponce Enriquez area (Ecuador) since more than 40 years. However, illegal and anti-technical mining practices have caused pollution and environmental degradation of the water resources. This study aims to assess the pollution degree of surface water and groundwater in the Tenguel and Siete watersheds. Concentrations of Pb, Fe, Zn, Mn, Cr, Cu, As, and Cd in 18 samples from rivers and wells were assessed. The level of water contamination was evaluated by the Metal Index (MI). As a result, an enrichment in the concentration of Cu, Pb and As was evidenced, which exceeded the maximum permissible limit of the Ecuadorian regulations, up to 128, 12 and 10 times, respectively. Regarding the MI, 60% of the surface water samples were seriously affected, with the Siete river being the most polluted among the water courses in the zone. The overview of the pollution degree in Ponce Enriquez water resources can serve as an input for decision makers on water protection issues.