Mobility and Bioavailability of Lead in Contaminated Boreal Forest Soil

Abstract

Effects of pine (Pinus sylvestris) and liming (pH-change with CaCO3) on the mobility and bioavailability of Pb (lead) in boreal forest soil, previously used as a shooting range area, were examined in laboratory microcosms. Solubility and mobility of Pb were measured, and bioavailability of Pb was assessed directly using a luminescent bacterial sensor for Pb. Results showed that pine seedlings had a major role in the immobilization of Pb in the contaminated soil. The presence of pine seedlings reduced the amount of water soluble Pb by 0−56% in humic rich surface soil and by 12−93% in mineral soil (5−20 cm) and also decreased by 40−57% the mobility of Pb in the surface and mineral soil. Liming did not reduce the solubility, mobility or bioavailability of Pb in the soil. Significant positive correlation was found between the concentration of total water soluble Pb and the bioavailability of Pb in the soils. The concentration of bioavailable Pb was not, however, predictable from the concentration of total water soluble Pb; bioavailable Pb was only 4−6% of total water soluble Pb in humic surface soil and 13−43% in mineral soil.