Assessment of metal(loid)s availability and their uptake by Pinus halepensis in a Mediterranean forest impacted by abandoned tailings

Abstract

Tailings are frequently source of pollution in mining areas due to the spread of metal(loid)s from their bare surfaces via wind, water run-off and/or leaching. For this reason, areas surrounding tailings may be affected by high concentrations of those toxic chemical elements. The aim of this study was to determine the influence of soil parameters on metal availability in a Mediterranean forest affected by mining contamination and the potential employment of Pinus halepensis as a suitable plant species for phytostabilising mining polluted sites under semiarid climates. Five tailing sites, including their surroundings were selected. At the same sampling area, additional soil samples were taken in less impacted zones (up to 1km and 3km far from tailings). The highest total concentrations occurred indistinctly at some forest samples closed to tailings (e.g. ∼12,000mgkg−1 Pb) or tailing ones (∼790mgkg−1 As). The alkaline soil pH and some carbonate minerals conditions low CaCl2-extractable metal(loid) concentrations and therefore low risk of pollutants leaching. CaCl2-extractable As and metal concentrations did not correlate with the corresponding concentrations in pine needles indicating that this procedure might not be suitable to predict metal(loid) availability in pine trees. Needles of pine trees from the less impacted areas showed lower Mn and Zn concentrations (40–100mgkg−1 Mn, 25–55mgkg−1 Zn) in relation with the ones taken from the tailings. P. halepensis Miller looks a suitable plant species to be employed in the phytostabilisation of tailings due to the higher root systems, which may provided a better soil retention, and its relative low metal accumulation.