Cited by 280Heavy metals in environmentEnvironmental and Analytical Chemistry StudiesChromium effects and bioremediation

Impacts of phosphate amendments on lead biogeochemistry at a contaminated site

Cao, Xinde, Ma, Lena Q., Chen, Ming, Singh, Satya P., Harris, Willie G.·2002·Environmental Science & Technology

Abstract

Soil amendments can be used to cost-effectively reduce the bioavailability and mobility of toxic metals in contaminated soils. 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. Phosphate amendments effectively transformed soil Pb from the nonresidual (sum of exchangeable, carbonate, Fe/Mn, and organic) to the residual fraction, with residual Pb increase by 19-48% for T1, 22-50% for T2, and 11-55% for T3, respectively. Lead immobilization was attributed to the P-induced formation of chloropyromorphite [Pb10(PO4)6Cl2], which was identified in the surface soil, subsurface soil, and plant rhizosphere soil. Occurrence of chloropyromorphite was evident 220 days after P addition for T1 and T2 treatments and 330 days for T3. Visual MINTEQ model and activity-ratio diagram indicated that lead phosphate minerals controlled Pb2+ activities in the P-treated soils. Phosphate treatments significantly reduced Pb translocation from the roots to the shoots in the St. Augustine grass (Stenotaphrum secundatum), 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. Lead immobilization shows a long-term stability. A mixture of H3PO4 and phosphate rock yields the best overall results for in situ Pb immobilization, with less soil pH change and less P leaching. 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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Crossref · 10.1021/es020697j

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  • A field study at a Pb-contaminated site showed that phosphate amendments significantly reduced Pb mobilization through formation of chloropyromorphite [Pb10(PO4)6Cl2].

    “A field study at a Pb-contaminated site showed that phosphate amendments significantly reduced Pb mobilization through formation of chloropyromorphite [Pb 10 (PO 4 ) 6 Cl 2 ] (Cao et al., 2002).”

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Authors
Cao, X., Ma, L. Q., Chen, M., Singh, S. P., & Harris, W. G.
Affiliations
University of Saskatchewan (CA)
Venue
Environmental Science & Technology
Published
2002-11-13
Volume
36
Issue
24
Pages
5296-5304
ISSN
  • 0013-936X (ISSN-L)
  • 1520-5851
OpenAlex
W2031703337
Cited by
280
References
27
Citations by year
2026: 8 · 2025: 9 · 2024: 3 · 2023: 10 · 2022: 5 · 2021: 12 · 2020: 18 · 2019: 11 · 2018: 22 · 2017: 14 · 2016: 19 · 2015: 16 · 2014: 20 · 2013: 12 · 2012: 16
FWCI
5.55
Type
journal article
Language
en
Open access
closed
Locations
  • Environmental Science & Technology (publishedVersion)
  • PubMed (publishedVersion)
Funders
U.S. Environmental Protection Agency
Topics
  • Physical Sciences › Environmental Science › Pollution › Heavy metals in environment
  • Physical Sciences › Environmental Science › Water Science and Technology › Environmental and Analytical Chemistry Studies
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Chromium effects and bioremediation
Keywords
phosphate amendment, lead immobilization, phosphate rock, soil remediation, lead bioavailability, lead translocation, Stenotaphrum secundatum, lead phosphate minerals, soil pH, phosphorus leaching, contaminated soil
MeSH terms
Calcium, Environmental Pollution, Poaceae, Hydrogen-Ion Concentration, Lead, Microscopy, Electron, Microscopy, Electron, Scanning, Minerals, Phosphates, Phosphorus, Soil, Soil Pollutants

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