Speciation of lead, zinc and cadmium in contaminated soils from Mežica valley

Abstract

A knowledge of the total amount of heavy metals in soil is not enough to assess the environmental impact and decide on suitability of polluted soils for agronomic use. Six-step sequential extraction procedure was used to determine the distribution of Pb, Zn and Cd among various fractions of soils from six locations in Mežica valley. Phyto-available heavy metals: water soluble heavy metal species and fraction exchangeable from colloids to soil solution, accounted in average for 0.23-1.14% of Pb, 0.36-3.88% of Zn and 0-8.2% of Cd. The majority of heavy metal species was found to reside in non phyto-available carbonate fraction, fraction bound to Fe and Mn oxides, fraction bound to organic matter and residual fraction. Among soils tested the significant variations in distribution of heavy metals among different soil fractions were observed, presumably due to differences in soils characteristics.

Keywords

• contaminated soil
• lead
• zinc
• cadmium
• speciation