comparison of synthetic chelates and compost at enhancing phytoextraction of cd, ni and pb from contaminated soil under canola cultivation

abstract the plants which can be used to clean up the soil of heavy metals contamination are named phytoremedation. phytoremediation has received increasing attention because of its low environmental impact and cost-effectiveness. but, it is slowly process and needs long time. in such reson, chelating agents have been proposed to improve the efficiency of phytoextraction by increasing solubility of target metals from soil. synthetic chelates and low molecular weight organic acids are the most common chemical amendments that have been used in chemically assisted phytoextraction of metals from soils. the objective of this work was comparison of edta and sugarcane by product compost in enhancing phytoextraction of cd, pb, and ni by canola in an artificially contaminated soil. two levels of contamination (800 and 1600 ppm) were performed. the soil were placed in dark condition for 2 weeks and compost of sugarcan were applied in two levels (20 and 50 ton per hectar). a number of 5 canola seeds with grower power 95% germination were cultivated. two weeks after cultivation, the treatments included edta in numbers of (0,10,20mmol /kg soil) with irrigated water were added to the pots. eight weeks after cultivating the plants cut as well as the analysis of the soil and the plant in the laboratory was made. all treatments significantly increased the concentrations of cd, pb and ni in the shoots of plants compared with the control. therefore, the influence of edta and compost were observed more powerful for enhanced phytoextraction of the heavy metals. the effectiveness of edta and compost to stimulating the accumulation of cd, pb and ni in shoots plants were (4.3 and 4.1), (4 and 4.2) and (2.8, and 2.9) times more respectively, than the control. also, the results of this study indicated that all treatments were superior in terms of solubilizing soil pb, cd and ni for root uptake and translocation into shoots canola but, in different levels.