Small-scale Gold Mining in the Puyango River Basin,Southern Ecuador: A Study of Environmental Impacts andHuman Exposures |
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Authors: | Email author" target="_blank">Oscar?BetancourtEmail author Alberto?Narváez Marc?Roulet |
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Institution: | (1) Fundación Salud Ambiente y Desarrollo (FUNSAD), P.O. Box 17-07-9382, Quito, Ecuador;(2) HYBAM UMR 154 LMTG, Institut de Recherche pour le Développement (IRD), La Paz, CP, 9214, Bolivia |
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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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Keywords: | mining environmental impacts mercury lead manganese Ecuador |
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