Germination and seedling development of selected Mediterranean aromatic plants in heavy metal contaminated soils: A preliminary study for the recovery of mining sites in Sardinia

Mining has caused serious contamination issues worldwide. Abandoned mines release toxic elements into the environment and generate pollution, with potential consequences for plant and human health. The aim of this research was to explore the influence of heavy metal contaminated soils from former mining sites in Sardinia (Italy) on the germination and seedling development of six aromatic plant species common to the Mediterranean area. Contaminated soils were retrieved from two sites in Sardinia (Italy): site 1 (Montevecchio, MV) was polluted by As, Cd, Cu, Pb, Sb and Zn, while site 2 (Su Suergiu, SS) by As, Pb, Sb and Zn. A significant impact was observed on most of the germination and seedling parameters between species and treatment. Su Suergiu soil had a dramatic effect on Achillea millefolium, Artemisia dracunculus and Thymus vulgaris, showing > 85 % rate of seedling death after germination. Based on germination and biomass parameters, Salvia officinalis emerged as the most tolerant species in both contaminated soils, as evidenced by the lowest seedling death rate (<5 %) and the highest vigor. Labile As, Sb and Zn in SS soils had a clear negative impact on the seed germination and seedling development. Overall, Ocimum basilicum and Salvia officinalis were identified as potential candidates for the remediation and agricultural redevelopment of heavy-metal contaminated soils.