Study on Immobilizing Soil Exogenous Lead Using Phosphate Rock

The effect of phosphate rock (PR) on exogenous Pb fractions in yellow cinnamon soil (S1) and latosol soil (S2) were studied by Tessier's sequential extraction procedures after PR was applied into the two soils at four levels of 0, 50, 500 and 2000 mg.kg(-1). The results indicated that the content of exchangeable Pb in two soils decreased significantly with the rising of PR amount, which reached the minimum of 2.95 mg.kg(-1) for yellow cinnamon soil and 3.57 mg.kg(-1) for latosol soil under the treatment of 2000 mg P.kg(-1) soil (PR3). Both of the residual fractions of Pb in the two soils reached the maximum under the treatment of 2000 mg P.kg(-1) soil, 38.5 mg.kg(-1) for yellow cinnamon soil and 66.1 mg.kg(-1) for latosol soil. To sum up, the content of exogenous exchangeable Pb decreased and the residual fraction augmented conversely for both soils after the two soils being applied with testing PR. In conclusion, the result reflected that Pb had been immobilized effectively by PR in two tested soils.