Geochemistry analysis of rare earth elements of southern Italy soils.

Soil pollution has become an important environmental issue in developed countries due to urban-industrial development. Among other pollutants, heavy metals are especially dangerous because of their persistence and toxicity. In general, the mobility and availability of heavy metals are controlled by absorption and desorption characteristics of soils, in particular they can be associated with soil properties including pH, organic matter content. The aims of this study were to determine contents of Ag, Be, Bi, Cd, Co, Cr, Cu, Ni, Pb, Sn, Tl, Zn related to intervention values imposed by Italian government and to establish relationships between heavy metals and some soil properties in an olive orchard of southern Italy. Soil heavy metals content, pH, electrical conductivity and organic matter content were determined in 100 soil samples. Soil pH ranged from 5.73 to 7.45 i.e. strong acid to mild alkaline, organic matter contents ranged from 0.027 to 23.78 g/kg, electrical conductivity ranged from 106.80 to 654 µS/cm. These results indicated that the sampled soils covered a wide range of pH, organic matter and electrical conductivity being suitable for studying the influence of these soil properties on availability and plant uptake of heavy metals. Correlation matrix was used to identify the relationship between heavy metal contents and soil properties. The Italian government established intervention values for some toxic elements in soil. Among these, five elements exceeded the regulatory threshold value (Limit A of Italian Law no. 152/2006) in analysed soils.