Remediation of Petroleum-Contaminated Soils using Stipagrostis plumosa, Calotropis procera L., and Medicago sativa under Different Organic Amendment Treatments

Aims The contamination of soils and groundwater by toxic, hazardous organic pollutants is a widespread environmental problem. The use of vegetation for the treatment of contaminated soils is an attractive and cost-effective alternative, especially for petroleum-contaminated soils. Materials & Methods Three species including Calotropis procera L., Stipagrostis plumosa, and Medicago sativa were selected. To evaluate the abilities of S. plumosa, M. sativa, and C. procera in the degradation of petroleum hydrocarbons, a greenhouse study was conducted with two trial factors: (1) Urban waste compost and (2) biochar (each 0, 1, and 2%). At the end of the experiment, aerial and underground parts of the plants were collected, and some important soil properties and plant morphological characteristics were measured. The total amount of hydrocarbons was measured by gas chromatography, Flame Ionization type, Agilent 7890A model. Findings The results showed that the strongest hydrocarbon reduction by C. procera, S. plumosa, and M. sativa was 62.5%, 57.3%, and 53.5%, respectively. The results also demonstrated that control/biochar 2% had the highest/lowest (21922/14511 mg/kg) hydrocarbon level left in the soil. Therefore, biochar 1% or 2% is the best treatment for the remediation of petroleum-contaminated soils. C. procera L. is a good potential candidate to be cultivated for the phytoremediation of petroleum-contaminated soils. Conclusion Overall, using the amendment seedbed including biochar and urban waste compost treatments is suitable to promote phytoremediation of petroleum hydrocarbons. Biochar and urban waste compost provide optimal conditions for plant growth and at least help to promote the process phytoremediation. Regarding plant species diversity in Iran and petroleum contamination, application of phytoremediation may apply with effective and applied solution in soils contaminated.