Mineralogical and environmental features of the asturian copper mining district (Spain): A review

Persistence and bioavailability of heavy metals in soils adjacent to ancient Cu mines continues to be a possible threat to human health. However, there have been very few studies to determine this risk. Asturias (Northwest of Spain) is a Cu metallogenic province with abundant epithermal-type deposits, whose paragenetic sequences also include As, Co, Ni, Sb and Hg minerals. Several Cu mines have been worked in this region since prehistoric times and the six most significant ones are studied in this work to provide new insights into the potential for both contemporary and past contamination due to Cu mining to impact human health. The main characteristics of each deposit were defined by means of optical and scanning-electron microscopy, X-ray diffraction and Electron Probe Micro Analysis. These characteristics were used to better interpret the environmental results, obtained from samples of mining wastes, soils and waters, which were analyzed by means of X-ray fluorescence and ICP-MS. Many of these mines are almost forgotten, but their negative effects will endure over time, since they were abandoned long before the introduction of environmental regulations to control metal release. An inheritance of derelict mine facilities and spoil heaps still remains in the sites of this district. The spoil heaps are the main pollution sources and concentrations of up to 2.1% Cu and 0.4% As, among others, were found in the surrounding soils. The potential adverse health effects of the exposure to these elements have been assessed, finding significant risks for potential receptors, such as farmers or local residents.