The Use of Phosphorus and Other Soil Amendments for in Situ Stabilization of Soil Lead

Key words: in situ stabilization, bioavailable PB, soil remediation This study was conducted to evaluate the effects of P, Mn oxide, and time on bioavailable Pb in five metal-contaminated soils or mine spoils in the absence or the presence of plants, and to evaluate the effect of those treatments on phytoavailability of Pb, Cd, and Zn. The addition of P or Mn oxide reduced bioavailable Pb compared to control, as measured by a modified physiologically based extraction procedure (PBET). The maximum reduction in bioavailable Pb was always observed with the addition of P and manganese oxides together. X-ray diffractometry analyses support the PBET results, indicating that more " pyromorphite-like minerals " may have formed in the presence of both P and Mn oxides. Synergistic effects from the presence of Mn oxide with P in reducing Pb bioavailability were still evident after extensive cropping of the soils. Several mechanisms, alone or in combination, may have been responsible for this synergistic effect. The concentrations of Pb, Cd, and Zn in sudax and Swiss chard plant tissues were reduced in the presence of soluble P, and soluble P or insoluble P with Mn oxides. This new improved in situ technique to remediate Pb-contaminated soil and mine wastes has advantages over standard methods.