Especiación de Mercurio y Transformaciones Microbianas en el Distrito Minero de Almadén
Abstract
Speciation of Hg and conversion to methyl-Hg were evaluated in mine wastes, sediments, and water collected from the Almadén District, Spain, the world's largest Hg producing region. Our data for methyl-Hg, a neurotoxin hazardous to humans, are the first reported for sediment and water from the Almadén area. Concentrations of Hg and methyl-Hg in mine waste, sediment, and water from Almadén are among the highest found at Hg mines worldwide. Mine wastes from Almadén contain highly elevated Hg concentrations, ranging from 160 to 34,000 µg/g, and methyl-Hg varies from <0.20 to="" 3100="">
Isotopic tracer methods indicate that mine wastes at one site (Almadenejos) exhibit unusually high rates of Hg-methylation, which correspond with mine wastes containing the highest methyl-Hg concentrations. Streamwater collected near the Almadén mine is also contaminated, containing Hg as high as 13,000 ng/L and methyl-Hg as high as 30 ng/L; corresponding stream sediments contain Hg concentrations as high as 2300 µg/g and methyl-Hg concentrations as high as 82 ng/g. Several streamwaters contain Hg concentrations in excess of the 1000 ng/L World Health Organization (WHO) drinking water standard.
Methyl-Hg formation and degradation was rapid in mine wastes and stream sediments demonstrating the dynamic nature of Hg cycling. These data indicate substantial downstream transport of Hg from the Almadén mine and significant conversion to methyl-Hg in the surface environment.
Resumen
En este estudio se evaluó la especiación del mercurio y su conversión a metil-mercurio en residuos de minas, sedimentos y agua del distrito de Almadén, España, la mayor región productora de mercurio del mundo. Se encontraron altas concentraciones de mercurio y metil-mercurio en los diferentes elementos analizados, siendo algunas de las más altas a nivel mundial. Se detectaron tasas elevadas de metilación de mercurio en los residuos de un sitio específico en Almadenejos.
Se registró contaminación en arroyos cercanos a la mina de Almadén, con altas concentraciones de mercurio y metil-mercurio, superando los estándares de la OMS para agua potable. Se observó una rápida formación y degradación de metil-mercurio en los residuos de minas y sedimentos de arroyos, lo que indica un transporte importante de mercurio desde la mina y una significativa conversión a metil-mercurio en el ambiente superficial.