title: Environmental monitoring of the role of phosphate compounds in enhancing immobilization and reducing bioavailability of lead in contaminated soils.
abstract: Lead is a highly toxic element and forms stable compounds with phosphate, which is commonly used to immobilize Pb in soils. However, few studies have monitored the long-term stability of immobilized Pb, which is a critical factor in determining the effectiveness of the in situ stabilization technique. Both soluble and insoluble phosphate compounds were tested for Pb immobilization, and its subsequent mobility and bioavailability in a contaminated soil from a shooting range. Adding tricalcium phosphate, hydroxyapatite, rock phosphate and potassium dihydrogen phosphate reduced the concentration of ammonium-nitrate-extractable Pb in the contaminated soil by 78.6%, 48.3%, 40.5% and 80.1%, respectively. Insoluble phosphate amendments significantly reduced leached Pb concentration from the column while soluble potassium dihydrogen phosphate compound increased P and Pb concentrations in the leachate. Rock phosphate reduced Pb accumulation in earthworms by 21.9% compared to earthworms in the control treatment. The long-term stability of immobilized Pb was evaluated after 2 years' incubation of the contaminated soil with rock phosphate or soluble phosphate compounds. Bioavailable Pb concentration as measured by simple bioavailability extraction test (SBET) showed the long-term stability of immobilized Pb by P amendments. Therefore, Pb immobilization using phosphate compounds is an effective remediation technique for Pb-contaminated soils.
authors: Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, Mawson Lakes, SA 5095, Australia.
authors: Jin Hee
authors: JH
authors: Park
authors: Nanthi S
authors: NS
authors: Bolan
authors: Jae Woo
authors: JW
authors: Chung
authors: Ravi
authors: R
authors: Naidu
authors: Mallavarapu
authors: M
authors: Megharaj
mesh_terms: D000327:Adsorption; D000818:Animals; D001682:Biological Availability; D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007854:Lead / Q000302:isolation & purification* / Q000378:metabolism; D009835:Oligochaeta / Q000378:metabolism; D010710:Phosphates / Q000737:chemistry*; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D010710:Phosphates; D012987:Soil; D012989:Soil Pollutants; D007854:Lead