Abstract:To compare the stabilizing effects of sodium phosphate and sodium dihydrogen phosphate on lead-contaminated soil. This study used two domestic standard methods—"Solid waste-Extraction procedure for leaching toxicity-Horizontal vibration method"(SELH) (HJ 557-2009) and Solid waste-Extraction procedure for leaching toxicity-Acetic acid buffer solution method" (SELA)(HJT 300-2007).Using the above two methods to extract two kinds of lead-contaminated soil,which are stable with phosphate amendments(Na₃PO₄,NaH₂PO₄) was employed at a 3 and 8 P/Pb molar ratio in different incubation time(day:7,20,30). The SELA-Pb results show that Na₃PO₄ and NaH₂PO₄ amendment significantly reduced Pb mobilization. At the 30th day of culture, Na₃PO₄ was employed at a 8 P/Pb molar ratio, compared with the control group, SELA-Pb was reduced by 96.8%. The extraction results of SELH-Pb showed that the addition of Na₃PO₄ and NaH₂PO₄ increased the concentration of extractable lead in the soil compared to the control group, and addition of Na₃PO₄ in the YN and HN groups had a higher concentration of SELH-PB than addition of NaH₂PO₄. At the 30th day of culture, Na₃PO₄ was employed at a 8 P/Pb molar ratio, SELH-PB reached 3.72 mg/L. Under the conditions of this experiment, the two extraction methods have different extractable lead concentration trends within 7-30 days. The extractable lead concentration of the acetate buffer solution method shows a decreasing trend, while the horizontal shaking method extracts the lead concentration shows an upward trend. The addition of Na₃PO₄ and NaH₂PO₄increases the concentration of lead extracted by the horizontal shaking method in the soil, which has a certain risk to heavy metal lead contaminated soil, and Na₃PO₄ as a soil lead pollution remediation agent has a higher risk than NaH₂PO₄.