The interaction of heavy metals and metalloids in the soil–plant system in the São Domingos mining area (Iberian Pyrite Belt, Portugal)

Abstract

São Domingos belongs among the most important historic Iberian Pyrite Belt Cu mines. The anthrosoil is contaminated by a very high content of heavy metals and metalloids. The study was focused on evaluating the interaction of some chemical elements (Ca, Mg, Fe, Mn, Cu, Pb, Zn, Ag, Cd, Ni, Co, As, Sb) in the system soil vs. five autochthonous dominant plant species: Pinus pinaster Aiton, Quercus rotundifolia Lam., Agrostis sp., Juncus conglomeratus L. and Juncus effusus L. The plants are heavily contaminated by Cu, Pb, As and Zn. The bioconcentration factor proved that they exhibit features of metal tolerant excluders. The trees are accumulators of Ag, whereas the graminoids are hyper-accumulators of Ag and Juncus effusus of Co. The translocation factor confirmed that the selected elements are immobilised in the roots except for Mn and Zn in Pinus pinaster and Mn in Quercus rotundifolia and Juncus conglomeratus. The bioaccumulation of Mn, Zn and Cu at low pH increases. The increased content of Ca and Mg in the soil inhibits, in the case of some metals and metalloids, their intake to plants. Although the studied plants, despite their fitness and vitality at the contaminated sites, are not suitable for phytoextraction (except Co and Ag), they can be used for phytostabilisation at the mining habitats.