... main source of Pb contamination in urban soils The concentrations of Cu, Zn, Pb and Cr in non -urban soils are much lower than those in urban soils, and are not polluted by Cu, Zn, Pb and Cr Anthropogentic ... objective of this study was to determine the total Cu, Zn, Pb and Cr concentrations and chemical speciation of urban soils in Nanjing, China Materials and methods 2.1 Description of study area Nanjing ... of Cu, Zn, Pb and Cr concentrations in urban soils, and that soil horizons were scraped, filled, mixed, etc repeatedly can interpret vertical variability of Cu, Zn, Pb and Cr concentrations in...