Assessment of the environmental risks associated with two mine tailing soils from the La Union-Cartagena (Spain) mining district

Abandoned former mine spoil accumulation ponds are important sources of contamination for the surrounding areas, including villages and agricultural land. Characterisation of the contamination in these sites is therefore needed to assess the environmental risk associated with the possible dissemination of the pollutants. With this aim, physico-chemical parameters, trace element (TE) concentrations, solubility and speciation and the ecotoxicity of soils from two different sites, one acidic and the other neutral, within the mining district of La Union-Cartagena (SE Spain) were determined. All the soils had very high total, soluble and extractable TE concentrations, and free ions, metal-sulphates and organo-metal complexes were the predominant metallic forms found in pore water. In the case of As, H(2)ASO(4)(-) dominated in the samples from the acidic site. The soils showed elevated toxicity for different plant species (bean, sunflower and lettuce growth, as well as lettuce and cress germination, were strongly inhibited) and aquatic organisms (mortality was very high for both Thamnocephalus platyurus and Vibrio fischeri), due to both their high salinity and TE content. These soils are therefore in need of remediation, to reduce the environmental risk that they pose. (C) 2014 Elsevier B.V. All rights reserved.