Mercury fractionation in sediments downstream of the abandoned mine

Abstract. Asturias (Northern Spain) has been an important mercury mining area during the twentieth century. The mining and smelting of ore has been the responsible for the large release of mercury to the aquatic and terrestrial environments in the area. The present work sought to evaluate the fractionation of mercury in stream sediments from the Caudal River basin in central Asturias by using sequential extraction. A novel five-step sequential extraction procedure was used to assess Hg partitioning. Total mercury concentrations varied between 12 and 443 mg.Kg-1. Sequential extractions revealed that both Elemental Hg and bound to sulfide Hg constituted the major forms of mercury in the samples. Key words: sediment, mercury mine, sequential extraction, mercury fractionatio