The contents of the common elements (i.e. K, Ca, Mg, Al, Fe, Zn, and P) in biochars were determined and listed in Table 1. The contents of most studied elements in biochars produced at 550 °C were higher than those in biochars produced at 350 °C, which suggested that the ash contents of biochars produced at 550 °C were higher than those of biochars produced at 350 °C. The high Ca contents in PN biochars and high K contents in WS biochars implied that, in addition to immobilizing heavy metal, PN and WS biochars could also supply large amounts of nutrient elements to the soil. When raw biochars were washed by HCl/HF solution, the contents of the elements substantially dropped, this means that the factor of ash which may influence the sorption of Zn can be excluded in de-ashed biochars. The pHs of raw biochars and the pHPZC of de-ashed biochars were also listed in Table 1.