Extraction of heavy metals from contaminated soils: I. sequential extraction in surface soils and their relationships to DTPA extractable metals and metal plant uptake

This study was aimed to evaluate the quantity and bioavailability of five metals from five contaminated soils. A selective sequential fractionation procedure was used to separate the metals into six groups: water soluble, exchangeable, carbonate, Fe‐Mn oxide, organic, and residual. The residual fraction was the most abundant only for Pb in most soils, suggesting that Pb was probably more stable and less bioavailable in these soils. Lead, Cd, and Cu were not detected in the water‐soluble fraction of most soils. Although the greatest amounts of Zn and Cu in the non‐residual fraction were in general associated with the Fe‐Mn oxide fraction, and Ni with the organic fraction, an appreciable percentage of these metals were concentrated in the exchangeable or the carbonate bound fraction. As metal behavior in the environment is dependent upon its solubility and mobility in soils, the potential hazard of these metals in these contaminated soils was assessed in this study.