Effect of phosphate treatment on the solubility of lead in contaminated soil

Lead-contaminated soil was used for treatment testing with phosphate-based additives. Reactions controlling leached lead concentrations from soil befo re and after phosphate treatment were evaluated. The concentration of lead from untreated soil is controlled by a desorption reaction from hydrous met al oxides. Phosphate addition reduced lead solubility in the acidic PH rang e, but not in the alkaline range. The addition of chloride further reduced lead solubility. The phosphate-treated soil released lower concentrations o f lead in simulated digestion tests.