Consequences of abandoned Cu-Co mining in Northern Spain in surface watercourses

摘要

Prehistoric tools at the Texeo Mine indicate it is one of the oldest Asturian mining sites. The ore deposit was formed by metasomatic replacement related to fracture systems in Carboniferous limestones. The mineralization comprises major Cu-Co-Ni sulphides and arsenides, with minor concentration of precious metals. The mine site has been the most important source of Cu in the region since Roman times and nowadays, approximately 40,000 m~3 of wastes from mine and metallurgical operations containing average concentrations of 9,263 mg centre dot kg~(-1) Cu, 1,100 mg centre dot kg~(-1) As, 549 mg centre dot kg~(-1) Co, and 840 mg centre dot kg~(-1) Ni are accumulated on site, posing a threat to the environment, due to the potential release of toxic elements. A sequential systematic sampling has been undertaken in wastes, soils and waters, to outline anthropogenic anomalies, which have been found especially for As and Cu in soils, whereas concentrations up to 5 mg centre dot l~(-1) Cu have been detected in surface water downstream the mine works. Computer based risk assessment for the site gives a carcinogenic risk associated to the presence of As in waters and soils, and a health index risk for long exposures mainly associated to the presence of high contents of Cu in soils.