Lead (Pb) Contamination of a Historical Mining and Smelting Site in Europe: Fractionation and Human Bioavailability

Abstract

Nine soil and three tailing samples collected from a historical Pb mining and smelting site including a vicinity area in Europe were investigated for the chemical fractions and human bioavailability. A five-step sequential extraction procedure was performed to characterize the forms of Pb. A simple bioavailability extraction test (SBET) was conducted as an assessment to determine the bioavailability of Pb in human gastrointestinal condition. Total concentration of Pb in soil and tailing samples ranged from 383 to 73800 mg/kg. Eleven from twelve samples had exceeded the USEPA standard of 400 mg/kg. Fractionation of Pb showed that seven from twelve samples were mainly associated with a reducible fraction (Fe-Mn oxides) for 37.8 to 71.6%. Carbonate fractions were found dominantly in three soil samples of 62.0%, 57.4%,and 68.6%, repectively, with high pH and high total concentration of Pb. A residual fraction was prevalent for tailing samples. Low pH in tailing samples may influence the mobility of Pb and increasing of soil pH seemed to increase Pb content in the carbonate fraction. Extremely high values of Pb from human bioavailability assessment (SBET) (more than 60%) indicated that long-term exposure of these soils could pose a potential health effect to the local population.