Gentle remediation at the former "Pertusola Sud" zinc smelter: Evaluation of native species for phytoremediation purposes

The master plan for a soil clean-up of the former zinc smelter “Pertusola Sud” (Crotone, Italy) considered gentle remediation options for a specific area where both by-products and industrial wastes had been disposed in the past. Although the soil is severely contaminated by metals (Cd, Cu, Ge, Hg, In, Pb, Tl and Zn) and metalloids (As and Sb), several plant species grow spontaneously in this area. Plants and soil samples were collected and analysed for trace element concentrations. In the shoots of Dittrichia viscosa the Cd concentration (112 mg kg−1) exceeded the hyperaccumulation threshold. Phragmites australis and Silene bellidifolia concentrated about 30 and 40 mg kg−1 of Tl in their shoots, respectively. Sb accumulation in leaves of Acacia saligna, Eucalyptus camaldulensis and P. australis was more than 20 times higher than herbs. The highest Zn concentration in shoots was recorded in D. viscosa (1172 mg kg−1). The phytoremediation potential of plants was evaluated considering the concentration of metals and metalloids in the plant tissues and also the bioconcentration factor (BF) and translocation factor (TF). The plant requirements for Sb phytoextraction were verified for P. australis (1.66 BF, TF 9.02), and for E. camaldulensis (BF 1.11, TF 1.71) and Galactites elegans (BF 2.30, TF 1.37) for Tl. Scirpoides holoschoenus could be considered for phytostabilization and recommended to restore a green cover on bare soils at the Pertusola Sud site.