Compared with the spectra of PN550, two more peaks appeared in the spectra of PN550 + Zn, which may belong to hydrozincite. Thus the formation of hydrozincite could be one of the mechanisms for Zn immobilization on PN550. In WS350 + Zn and WS550 + Zn, as sylvine is soluble, only quartz was maintained on WS350 and WS550. Although WS350 and WS550 had considerable sorption capacities of Zn2+, none of the Zn species could be detected from the two samples by XRD analysis. This may be caused by the poor crystallinity of Zn species formed on WS350 and WS550. As the characterization way of XRD has the requirement on sample crystallinity, the method of XAFS was applied in Zn species identification.