may represent calcium lead phosphate hydroxide (PbxCa10-x (PO4)6(OH)2)) by ICDD (2012) (Fig.1). It
was consistent with the study of Laperche et. al.. that they may represent mixed Ca-Pb phosphates [24].
Furthermore, the intensity of peaks at 2.52Å (2θ=35.53°), 2.49Å (2θ=36.01°) and 3.77Å (2θ=23.50°)
increased in nHA-treated soil. They were lead dihydrogen phosphate, Pattersonite and lead phosphate,
reapectively. This showed that one of the mechanism of metals immobilization by nHA was the
dissolution of HA and the precipitation of new metal phosphate minerals.