Abstract:

The experiment was conducted to study the dose-response relationship of soil lead (Pb) and cadmium (Cd) concentration with their uptakes by Pakchoi (Brassica chinensis L.), as well as their environmental critical values in Pakchoi production area for food security. The results showed that: (1) generally, the contents of Pb and Cd in the edible parts of Pakchoi increased along with the concentrations of soil Pb and Cd in two soil types (Alluvial soil and Paddy soil). Compared with the control, the highest contents of Pb in the edible parts of Pakchoi increased by 18.31 and 9.49 times, and the highest contents of Cd increased by 15.4 and 10.04 times in the two types of soil, respectively; (2) Pb and Cd in the Paddy soil were easily enriched by the crop than in the Alluvial soil. Pb and Cd concentrations in the edible parts of Pakchoi in the Paddy soil were 2.54 and 1.92 times higher than those in the Alluvial soil, respectively, under the same treatment level; (3) based on the National standards for maximum levels of heavy metal contaminants in foods (GB-2762-2005), the environmental critical values of soil Pb and Cd in the Paddy field were calculated as 36.54 mg?kg-1 and 0.3 mg?kg-1, respectively, which were equal or lower than those in National standards of soil security (HJ332-2006). The environmental critical values of soil Pb and Cd in the Alluvial field were calculated as 110.21 mg?kg-1 and 1.09 mg?kg-1, respectively, which were higher than those in National standards of soil security (HJ332-2006).