Effect of Organic Amendments on Biodegradation of Diesel Oil in Pb and Cd Polluted Soil Enriched with Vermicompost Under Ornamental Sunflower Cultivation

Background: Remediation of heavy metals contaminated soils is a crucial issue. This study was conducted to evaluate the effect of nano Fe-oxide and multiwall carbon nanotubes (MWCNs) on diesel oil bio-degradation in the soil polluted with Pb and Cd  and enriched with vermicompost under ornamental sunflower cultivation. Methods: Treatments were soil application of MWCNs at the rates of 0, 1, and 2 % (W/W); 0, 15, and 30 t/ha vermicompost; 0 and 0.5 % (W/W) nano Fe-oxide in soils polluted with Pb and Cd as well as 0, 4, and 8 % (W/W) diesel oil. After harvesting, the Pb and Cd concentrations of plant and soil were determined using AAS. Furthermore, the diesel oil bio-degradation in the soil was measured. Results: Using 1 and 2 % (W/W) MWCNs significantly increased the diesel oil bio-degradation by 15.3 and 17.4%, while the Pb concentration in soil decreased by 13.1 and 15.8%. In addition, the Cd concentration, decreased by 14.2 and 16.1%, respectively. The Pb and Cd concentrations in plant showed the similar trends. Using vermicompost significantly increased the diesel oil bio-degradation. Conclusion: Using nano-Fe oxide and MWCNs significantly increased the biodegradation of diesel oil in soils polluted with Pb and Cd.