Investigation of Cadmium Uptake and Distribution in Different Sectors of Common Vegetables in the Country

The purpose of this study was to determine the influence of different levels of cadmium concentration of the soil on accumulation of cadmium in various parts of seven different types of common vegetable crops: lettuce, spearmint, coriander, cress, onion, parsley and leeks. A factorial experiment in a completely randomized design with three replicates and three treatments was conducted. The treatments included three levels of cadmium concentration in soil 50 mg.kg-1, 100 mg.kg-1 and control with no cadmium. The soil used in this study was prepared by using a sieve with a 2mm mesh and adding nitrate cadmium plastic pots were employed to cultivate vegetables. At the end of the growing season, samples were prepared from different parts of the plants to measure cadmium concentration. The SPSS software was employed to analyze the data. The results showed that cadmium concentrations were higher than 0.05 to 0.1 mg/kg and 0.2 mg/kg, the rates that Institute of Standards and Industrial Research of Iran and FAO/WHO, respectively, announced as safe for human consumption. Cadmium was found in stems: of lettuce, spearmint, coriander, cress, onion, parsley and leeks from highest to lowest; in leaves: of lettuce, cress, onion, coriander, parsley, spearmint and leeks; from highest to lowest; and in; roots: of cress, lettuce, spearmint, coriander, parsley, onion and leeks from highest to lowest. The results indicated that the highest amount of cadmium concentration among the different parts of the vegetables was founded in lettuce stem (6.8 mg/kg) and the lowest amount in leek root (0.77 mg/kg), both higher than what has determined as safe for human consumption. All treatments were considered as unsafe treatment while no sign of toxicity was found in control sample. The high accumulation of cadmium in lettuce, cress and onion, the vegetables that are consumed more, is critical due to their potential to accumulate this element in their leaves. These vegetables cannot be safe for consumption by human if is grown in soils with high concentration of cadmium.