Soil lead bioavailability and in situ remediation of lead-contaminated soils: A review

The environmental risk from soil lead (Pb) is related to its bioavailability. Soil Pb bioavailability depends on the solubility of Pb solid phases and other site-specific soil chemistry, suggesting that in situ stabilization of soil Pb can be accomplished by changing soil Pb chemistry. This paper presents a review of soil Pb bioavailability and an evaluation of in situ stabilization methods that can be used to reduce Pb bioavailability. A promising in situ approach involves the amendment of Pb-contaminated soil with phosphorus (P) in various forms or P with other amendments. Two general categories of P are insoluble forms, such as phosphate rock or synthetic apatites, and soluble forms typically present in commercially available fertilizer products or phosphoric acid. Numerous indirect assessment techniques show marked reductions in soil Pb biovailability upon addition of P and other amendments to Pb-contaminated soils. The techniques include physiologically based extraction tests, plant uptake of Pb, and other soil Pb extraction method. More directly, animal feeding studies also show reductions in soil Pb biovailability. In situ stabilization of soil Ph using P and other soil amendments is an emerging technology integrating soil chemistry, agricultural practices, and engineering that is gaining public and regulatory acceptance. (C) 2004 American Institute of Chemical Engineers Environ Prog, 23: 78-93, 2004.