Environmental monitoring of the role of phosphate compounds in enhancing immobilization and reducing bioavailability of lead in contaminated soils

Jin Hee Park, Nanthi S. Bolan, Jae Woo Chung, Ravi Naidu, Mallavarapu Megharaj

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)2234-2242
Number of pages9
JournalJournal of Environmental Monitoring
Volume13
Issue number8
DOIs
Publication statusPublished - Aug 2011
Externally publishedYes

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