In Situ Stabilization of Soil Lead Using Phosphorus and Manganese Oxide

Abstract

In addition to the formation of insoluble lead (Pb) compounds, adsorption is another potentially important process controlling the bioavailability of Pb in soils. Less attention has been given to manganese (Mn) oxides, even though they are known to adsorb Pb more strongly than any other metal (hydr)oxides. This study was conducted to evaluate the effects of P and Mn oxide on bioavailable Pb in five metal-contaminated soils or mine spoils from Kansas and Missouri. Cryptomelane was used as the representative Mn oxide. Nine treatments were used: zero P, 5000 mg of P as triple superphosphate (TSP) or phosphate rock (PR), 2500 and 5000 mg of Mn oxide/kg, and combinations of Mn oxide and P as TSP or PR. Changes in bioavailable Pb over time were measured using a modified physiologically based extraction procedure (PBET), and mineralogical changes were observed using X-ray diffraction. The addition of P or cryptomelane reduced bioavailable Pb in all five materials. The addition of P and cryptomelane together was...