The leaching flux was estimated based on previous study (Bengtsson et al., 2006) which collected the leaching water at 20-cm depth rather than 80-cm depth in Hou et al. (2014). Then the leaching flux was recalculated based on the previous data, the b of Freundlich parameter derived from pH, and the total concentration of heavy metal in the topsoil of YRD. The annual net fluxes for a certain heavy metal were calculated by using the following equations