Impact in soils caused by metal(loid)s in lead metallurgy. The case of La Cruz Smelter (Southern Spain)

Abstract

The old mining district of Linares (Southern Spain) was subject to intense Pb mining, minerallurgical and metallurgical activities for centuries, causing significant contamination of nearby soils. In this area the present study analysed the surroundings of the former lead smelter of La Cruz, where, in previous studies, soils with high metal(loid) contents were detected. To determine the intensity, spatial distribution and dispersion mechanisms of different trace elements, a geochemical prospecting campaign was designed in which 44 samples were collected from a 2.2 km2 surface area around the smelter. Of the 33 elements analysed, nine metal(loid)s (Cu, Pb, Zn, Ag, As, Sb, Bi, Cd and Tl) were found to have a high enrichment factor (EF). These elements show mean concentrations of 672, 6491, 464, 2.8, 75, 20, 2, 13 and 2.9 mg kg−1, respectively, values which largely exceed the levels of the environmental quality standards for soils established by both regional and European regulations. Multivariate analysis and geostatistical distribution maps enabled the most intensely contaminated areas to be characterised.The results obtained indicate that the main contamination zone is related to the smelter itself, with two different dispersal mechanisms: the first is linked to the gases and dust emissions generated by the metallurgical processes, and transported by the prevailing winds, in Southwest-Northeast direction; the second is associated with the leachate produced in the smelter residues. Additionally, two other secondary foci are formed by tailings ponds and mining residues. The contamination areas are known to affect a residential zone near the old smelter installations and land located Northeast of these areas, where there is an olive grove. The results of this study should therefore serve as a basis for the adoption of corrective measures to minimize the adverse effects on the soil from the old mining-metallurgical activities.