Study of Zn, Cu and Pb content in plants and contaminated soils in Sardinia

Trace elements in soils exist as components of several different fractions. In this work we have analyzed the relationship between these fractions. Specifically, total and extractable (with EDTA, calcium chloride and deionized water) Zn, Pb and Cu concentrations have been studied. In addition, their correlation with the concentration of these elements in plant leaves has been investigated. Soil and plant samples have been taken from Sulcis-Iglesiente, in southwest Sardinia (Italy), an area rich in mining tailings. This has made that the concentrations of the trace element under study in soils were varied. Three plants have been studied: Dittrichia viscosa, Cistus salviifolius and Euphorbia pithyusa subsp. cupanii. Soil samples beneath each of them at depths of 0-30 and 30-60 cm have been considered. The highest concentration of trace elements in the leaves of the studied species have been found for Zn. In general, the calcium-carbonate content and the crystalline and amorphous forms of iron in the soil have determined the concentration of metal in plant leaves. The soil concentrations that have been found with the extraction methods are uncorrelated with Pb and Cu concentrations in plants, but Zn is correlated with the fraction extracted with EDTA and calcium chloride