Heavy metals in wheat grown in sewage irrigation: a distribution and prediction model

The distribution of and prediction models for heavy metals in wheat were evaluated in Tianjin, China. The results indicated that there were high heavy metal concentrations (Zn, Cd, Cu, Pb, Cr, and Ni) in the wheat and that the Cd concentration (0.062mg.kg-1) in the seeds actually exceeded the national safety standard. The accumulation factors for the wheat's seeds were of a decreasing order: Zn>Cd>Cu>Pb>Cr>Ni. The Cd concentration in the wheat's seeds corresponded closely with the Cd concentration in the soil (r = 0.74). The predicting model was appropriate for predicting the concentration of Cd and Zn in wheat, and the r was 0.735 and 0.625, respectively.