Soil and vegetation recovery in an area affected by residual pollution after remediation measures

Abstract

The present study evaluates the effectiveness of remediation treatments applied to residual polluted soils affected by the Aznalcóllar mining spill ocurred in 1998 (SW Spain). For this purpose, the influence of the treatments on the main soil properties and on the evolution of natural vegetation was studied. The results showed that amendments application improved the main soil properties and reduced soil toxicity, which led to a partial natural recovery of the vegetation cover and species richness in amended soils. Spergularia rubra and Lamarckia aurea, two of the main plant species present in the area and more strongly associated to high pollutant concentrations, showed a high bioaccumulation factor (BAF) for the main pollutants in the area (Pb and As) in shoots and, specially, in roots. Lamarckia aurea showed a remarkably high accumulation of these elements in roots, which is consistent with its distribution, strongly associated to areas where the vegetation growth is more restricted and where no other plant species are able to grow. Thus, both Spergularia rubra and Lamarckia aurea are important key species in this area, which may favour the subsequent colonization of the residual polluted soils by other less tolerant species to the pollutants present in these soils.