Effect of Multi-Walled Carbon Nanotubes, Salicylic Acid, and Drought Stress on Mazut Biodegradation Efficiency in a Pb- and Zn-Polluted Soil Under Cultivation of the Pinto Bean Inoculated with Piriformospora indica

Abstract

Abstract Aims: Today, remediation of soils contaminated with heavy metals and petroleum compounds is one of the major environmental problems. This research was done to investigate the effect of multiwall carbon nanotubes (MWCNs) and foliar application of salicylic acid (SA) on biodegradation of mazut in the Pb- and Zn-polluted soil under cultivation of the pinto bean inoculated with Piriformospora indica (P.indica). Methods: Treatments included applying MWCNs (0 and 2 % (W/W)) in the soil that was naturally polluted with Pb and Zn, foliar application of salicylic acid at the rate of 0 and 1.5 mmol/lit on the plants inoculated with P.indica under drought stress. In addition, the studied soil was polluted with mazut at the rate of 0% and 6% (w/w). After 3 months, plants were harvested and the plant Pb and Zn, the soil Pb and Zn, and the biodegradation of mazut in the soil were also measured. Results: Addition of MWCNS and foliar application of salicylic acid at the rate of 1.5 mmo/lit significantly decreased the soil Pb by 14.3 and 13.3%, respectively. Plant inoculation with P. indica significantly increased the biodegradation of mazut in the Pb- and Zn-polluted soil by 15.9%. However, drought stress had a negative effect on degradation of mazut in the soil. Conclusion: Regardless of plant expose to drought stress, using MWCNs and foliar application of SA has a positive effect on biodegradation of petroleum hydrocarbon in the soil.