Chapter 11 Antimony contents in plant species growing in an Sb-mining district (Tuscany, Italy)

We analyzed the antimony contents in 59 plant species (a total of 67 samples) from six sites in an Sb-mining area, each with a different Sb content in the soil. The plants were both cultivated and wild species, mostly herbaceous and tap-rooted, Dicotyledones, composites, grasses and legumes. The Sb concentration in plants is highly correlated with the concentration of total, soluble and extractable Sb in the soil, while the ability of the species to concentrate antimony is correlated only with the concentration of extractable Sb. Accumulation in roots is most responsive to the increase of available antimony in soils passing from the cultivated sampling sites to the mineral processing tailing pond. The most common site of Sb accumulation in the plant shifts from the roots to the leaves as the Sb content in the soil increases. Nevertheless, it appears to be largely species-specific. Antimony levels are high in plants from the tailing pond, above 1000 mg/kg in some wild species (Achillea ageratum, Silene vulgaris and Plantago lanceolata), while they are very low in crops and vegetables. Plant species traits, such as root morphology, life span, habitus and systematic rank, are important, although their influence is not statistically significant. All the plant species with the highest concentrations of antimony are herbaceous, almost all Dicotyledones, tap-rooted and mostly perennials, composites and legumes. The potential risk of the entry of antimony into food chains is discussed. The possible effects of plants on the environmental distribution of the element and the possible exploitation of some plant species as phytoremediators are also considered.