Impacts of Phosphate Amendments on Lead Biogeochemistry at a Contaminated Site

In this study a field demonstration was conducted at a Pb-contaminated site to evaluate the effectiveness of P-induced Pb immobilization

Xinde Cao; Lena Q. Ma; Ming Chen; Satya P. Singh; Willie G. Harris

2002

Scholarcy highlights

  • In this study a field demonstration was conducted at a Pb-contaminated site to evaluate the effectiveness of P-induced Pb immobilization
  • Phosphate was applied at a 4.0 molar ratio of P to Pb with three treatments: T1, 100% of P from H3PO4; T2, 50% P from H3PO4 + 50% P from Ca(H2PO4)2; and T3, 50% P from H3PO4 + 5% phosphate rock
  • Lead immobilization was attributed to the P-induced formation of chloropyromorphite, which was identified in the surface soil, subsurface soil, and plant rhizosphere soil
  • Visual MINTEQ model and activity-ratio diagram indicated that lead phosphate minerals controlled Pb2+ activities in the P-treated soils
  • Augustine grass, possibly via the formation of chloropyromorphite on the cell walls of roots. This field observation suggested that P amendments are efficient in reducing Pb mobility via in situ formation of insoluble chloropyromorphite minerals at a field setting
  • Application of combined H3PO4 with phosphate rock may provide an effective alternative to the current phosphate remediation technologies for contaminated soils

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