Bioaccumulation and translocation of cadmium in wheat (Triticum aestivum L.) and maize (Zea mays L.) from the polluted oasis soil of northwestern China

A pot experiment was conducted to study the bioaccumulation and translocation of cadmium (Cd) in wheat (Triticum aestivum L.) and maize (Zea mays L.) grown in the Cd-polluted oasis soil in northwest China. The results showed that Cd in the unpolluted oasis soil was mainly bound to carbonate fraction (F2) and Fe-Mn oxide fraction (F3). However, a marked change of the Cd fractionation was observed with increasing soil Cd concentrations, where the concentrations of Cd in F1 (exchangeable fraction), F2 and F3 increased significantly (P<0.001 for F1, F2 and F3). The correlation analysis between the fraction distribution coefficient (FDC) of Cd in the soil and Cd concentration accumulated in the two crops showed that Cd in F1 fraction in the oasis soil made the greatest contribution on the accumulation of Cd in the two crops. Higher bio-concentration factors (BCF) of Cd were observed in the two crops' shoots compared with grains, and low translocation factors (TF) of Cd in the grains were observed for both crops. Cd had a higher accumulation in the edible parts of the wheat, but lower accumulation in those of the maize. Therefore, wheat grown in Cd-polluted oasis soil has a higher risk to human health, whereas maize has a lower risk suggesting that wheat is not suitable for cultivation as crop and consumption by humans in the Cd-polluted oasis soil, but that maize is suitable for plantation.