title: In vitro lead bioaccessibility and phosphate leaching as affected by surface application of phosphoric acid in lead-contaminated soil.
abstract: Phosphate treatment of lead-contaminated soil may be a cost-effective remedial alternative for in situ stabilizing soil Pb and reducing Pb toxicology to human. The leaching behaviors of the P added to soil surface and the effect on subsurface Pb bioaccessibility must be addressed for this remedial technology to be acceptable. A smelter-contaminated soil containing an average of 2,670 mg Pb kg(-1), collected from the Jasper County Superfund Site located in Jasper County, Missouri, was surface treated with 10 g P kg(-1) as phosphoric acid (H(3)PO(4)). Following a simulated column leaching and 90-day treatment of field plots, respectively, bioaccessible Pb, P, and pH in soil profile were measured. Surface treatment using H(3)PO(4) effectively stabilized soil Pb and reduced leachable Pb and the bioaccessibility. Phosphate leached into deeper profile significantly lowered bioaccessible Pb in subsurface. Reduction of Pb bioaccessibility increased as a linear function of increasing soil P. Although surface H(3)PO(4) treatment resulted in an enhanced leaching of added P and may increase potential risk of surface and groundwater pollution, the P leaching under field conditions is very limited. Lime addition following the treatment may reduce the leachability of added P and further immobilize soil Pb.
authors.affiliation: Department of Geological Sciences, College of Veterinary Medicine, and Department of Soil & Atmospheric Sciences, University of Missouri, Columbia 65211, USA. yangj@lincolnu.edu
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: D E
authors.initials: DE
authors.lastname: Mosby
authors.forename: S W
authors.initials: SW
authors.lastname: Casteel
authors.forename: R W
authors.initials: RW
authors.lastname: Blanchar
mesh_terms: D000818:Animals; D001682:Biological Availability; D006801:Humans; D007854:Lead / Q000493:pharmacokinetics* / Q000633:toxicity; D010758:Phosphorus / Q000737:chemistry* / Q000494:pharmacology; D011634:Public Health; D012989:Soil Pollutants / Q000493:pharmacokinetics* / Q000633:toxicity; D012995:Solubility; D014872:Water Movements; D014873:Water Pollutants / Q000493:pharmacokinetics* / Q000633:toxicity
chemical_list: D012989:Soil Pollutants; D014873:Water Pollutants; D010758:Phosphorus; D007854:Lead