Environmental assessment and remediation options for a historic mine site located in a semi urban area in the north of Spain

摘要

Asturias, in Northwestern Spain, has abundant abandoned Hg mines. As consequence of extractive and metallurgical activities where operations have been usually developed with little control on effluents and emissions, pollution is severe in some areas. In some of those sites, spoil heaps constitute important pollution sources where ecotoxic elements are dispersed through the environment by different pathways. In the humid climatological conditions of the region, weathering of wastes stored in spoil heaps is intense and occasionally surrounding soils and surface waters are intensively affected by pollution. According to the environmental risks that these unreclaimed mine sites suppose for human beings and ecosystems, remedial options must be considered. Containment of wastes in an on-site safe landfill has been made recently for the biggest spoil heap located at the site of La Pena - El Terronal (Mieres). Mercury anomalies in the atmosphere at the site of the mine and spoil heap remain after the isolation of the wastes. As content in surface waters increased notably during wastes mobilization, but they are decreasing with time, reaching maximum values of 5.1 mg.l~(-1) in 2003 (previously to the isolation of wastes, As values reached up to 7.9 mg.l~(-1)).