Mercury Speciation and Microbial Transformations in Mine Wastes, Stream Sediments, and Surface Waters at the Almadén Mining District, Spain

• Published in: Environmental science & technology Vol. 38; no. 16; pp. 4285 - 4292
• Main Authors: Gray, John E, Hines, Mark E, Higueras, Pablo L, Adatto, Isaac, Lasorsa, Brenda K
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15-08-2004
• Subjects: Applied sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Contaminated sediments; Continental surface waters; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Freshwater; Geologic Sediments - microbiology; Humans; Mercury; Mercury - chemistry; Mercury - metabolism; Methylmercury Compounds - analysis; Methylmercury Compounds - chemistry; Methylmercury Compounds - metabolism; Mines; Mining; Natural water pollution; Pollution; Pollution, environment geology; Risk Assessment; Rivers; Sediments; Soil and sediments pollution; Spain; Waste Disposal, Fluid; Water Supply - standards; Water treatment and pollution; Europe; Spain; Almaden Spain; Isotopic analysis; Drinking water; Tracer technique; Pollutant behavior; Sediments; Heavy metal; Transport process; Industrial waste; Surface water; Water quality; Stream; Water pollution; Acid mine drainage; Methylation; Mining industry; Mercury; Speciation; Mining waste
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es040359d

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 ng/g. 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 mines 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.