Evaluation of Uptake and Accumulation of Heavy Metals by Lettuce in Soil Treated with Inorganic Wastes of Lead and Zinc Factories

The lead-zinc industries are known to be one of the high-risk industries in terms of the environmental issues. In this research, 15 samples of waste (cake) from Zanjan Lead and Zinc Factory were collected and six samples were selected for adding to soil according to type and concentration of heavy metals. Then, lettuce was planted in soil samples treated with different cakes. After harvesting the plants, the plant growth indices, concentration of heavy metals in plant roots and leaves, and available concentration of heavy metals in the cultivated soil were measured. This research was carried out as a completely randomized design, in which, six types of cakes were tested at three levels (0.25, 0.5 and 1%) with three replicates and three control samples (without adding the cakes). Results indicated that the highest amount of pollution for total concentration of heavy metals was related to Cd (168333 mg/kg), Zn (100000 mg/kg), Fe (91666 mg/kg), Mn (25566 mg/kg) Pb (13483 mg/kg) and Ni (7966 mg/kg), and for available concentration of heavy metals was related to Mn (21400 mg/kg), Zn (16400 mg/kg), Cd (4520 mg/kg), Pb (2371 mg/kg), Ni (194 mg/kg) and Fe (11.2 mg/kg). Available concentration of heavy metals in soils treated with cakes was reduced by uptake of these metals by lettuce