Environmental geochemistry of a highly polluted area: The La Union Pb–Zn mine (Castilla-La Mancha region, Spain)

Abstract This paper presents the results of a study concerning the total and extractable concentrations of eight elements (As, Cd, Cr, Cu, Ni, Pb, Se and Zn) in soils and sediments from La Union mine (Toledo province, Castilla-La Mancha region, central Spain). It also presents the extent of the heavy metal contamination produced by the mining activities. Our results show that the study area can be considered as a heavily polluted site as consequence of the mining process carried out locally. This is demonstrated by the total concentrations of all studied elements, which are much higher than the World's and the Castilla-La Mancha's averages for soils. The elements that present the highest concentrations (total and extractable) are zinc and lead. Sediments show higher mean total concentrations than soils for all the studied elements. They also show the highest extractable concentrations due to the influence of the stream in the weathering of this type of materials. The areas affected by high concentrations of arsenic and heavy metals depend on the studied element, reaching the maximum extension and importance for lead and zinc. In the study area, the environmental damage can be increased by the low pH obtained since it implies an increase in the mobility of most of the studied elements.