Abstract
This study addresses the impact of small-scale gold mining on the environment and communities of the Puyango River basin in the southwest of Ecuador between 1999 and 2001. Our primary objectives were to measure mercury, manganese, and lead in the river, to identify pathways of population exposure, and biological indicators of human exposure. A multi-method design at the catchment scale was applied to the analysis of water, sediments, and particulate matter for mercury, lead, and manganese over two different seasons. A household survey was undertaken, and individuals were assessed for lead (blood samples), and for mercury (urine and hair samples). River water samples had high concentrations of particulate matter (700 mg/L). Mercury and lead levels in water at the gold processing plants were very high in both seasons (250 ng Hg/L and 160 μg Pb/L). Mercury and lead, there was a downstream gradient with the areas adjacent to the gold processing plants having the highest levels. In Portovelo, the Upper Basin city, 14% of the population reported occupational exposure to inorganic mercury. Although no one in Portovelo consumes water from the river, 10% of the population consume local fish. This contrasts the Lower Basin where 98% of the population consume fish, and 100% use river water for drinking and cooking. Lead blood levels over 20 μg/dl were found in 39.4% of the study population and blood mercury over 10 μg/L only in 10.0%. Urinary mercury over 4 μg/L was found in 66.5% of the examined persons. Hair methylmercury did not exceed the safe limit of 2 μg/g, the mean concentration was 1.2 μg/g. Mining activity and erosion contributes to heavy-metal contamination (mercury, lead, and manganese) throughout the Puyango Basin. The relation between environmental contamination is complex and further research is being conducted to understand these relations.
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Acknowledgments
This study was possible with the wide and steadfast participation of the communities of the Puyango Basin. It could not have taken place without the collaboration of community leaders Néstor Córdova, Ausberto Córdova, Ilter Sócola, Faustino Feijó, Juvenal Gallo, Nicanor Calderón, Amado Lapo, and Oscar Rodríguez. We always had the moral support of the municipal authorities of Zaruma, Portovelo, Puyango, and Las Lajas. Our work was facilitated due to the logistic support of the “John Dewey” School and Health Center of Portovelo. The technical support by our dear consultant Donna Mergler is inestimable. The staff of SERVIGEMAB in Loja deserves a special mention for the environmental studies. We thank Guadalupe Sierra and Beatriz Vargas of INH Ecuador, and Jean Remy Guimaraes and Olaf Malm of the Federal University of Rio de Janeiro for laboratory analysis. This study was financially supported by the International Development Research Center (IDRC) of Canada (Grant 04291/98-0232).
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Betancourt, O., Narváez, A. & Roulet, M. Small-scale Gold Mining in the Puyango River Basin,Southern Ecuador: A Study of Environmental Impacts andHuman Exposures. EcoHealth 2, 323–332 (2005). https://doi.org/10.1007/s10393-005-8462-4
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DOI: https://doi.org/10.1007/s10393-005-8462-4