Mercury Speciation Transformations in Mine Waste, Sediment, and Water at the Almaden Mercury Mine, Spain

摘要

Hg speciation and potential rates of Hg transformations were determined in mine wastes, sediments and waters of the Almaden mining region. Mercury in wastes was highly elevated with total Hg from 160 to 34,000 mug/g and methyl-Hg from 0.15 to 3,100 ng/g. Stream water samples near the mine contained total Hg < = 13,000 ng/L and methyl-Hg < = 30 ng/L, whereas sediment samples contained total Hg of < = 2,300 mug/g and methyl-Hg < = 83 ng/g. Mine wastes contained high MeHg, but exhibited rapid demethylation and little methylation activity, except at a site with greater soil organic matter and high rates of methylation, and methyl-Hg levels >3,000 ng/g. Methyl-Hg-C in wastes and other soils was degraded reductively suggesting the involvement of mer genes. Stream sediments exhibited relatively rapid rates of methylation and demethylation, and an oxidative pathway of methyl-Hg degradation. Total Hg and methyl-Hg in the Almaden area are among the highest observed at Hg mines worldwide and this Hg is being transported downstream.