Phytoremediation of soils polluted with crude petroleum oil using Bassia scoparia and its associated rhizosphere microorganisms

• Bassia scoparia is a promising candidate for remediation of soils polluted with petroleum oil.
• Bassia scoparia is efficient in sulfur remediation and bioaccumulation.
• Phytoremediation reduces the toxicity of polycyclic aromatic hydrocarbons (PAHs).
• Moderate concentrations of PHs activate the oil-degrading microorganisms in soil.
• The oil-degrading microflora in the plant rhizosphere can remediate sulfur pollution.

The ability of Bassia scoparia (L.) A. J. Scott to remediate petroleum-contaminated arid land sandy soil was studied with natural and sterilized soils, and with supplemental nutrients and water. The species showed good tolerance of petroleum hydrocarbons (PHs) in soils reaching 2–3% (oil:soil by mass) pollution levels. After five months of phytoremediation, the average degradation rate of petroleum hydrocarbons ranged between 31.2 ± 1.15–57.7 ± 1.29% for natural soil and 28.7 ± 1.04–51.1 ± 1.53% for pre-sterilized soil. The highest breakdown of PHs for both saturated and poly-aromatic fractions was achieved when plants were present. Changes in saturated and aromatic fractions were monitored and measured using gas chromatography and high performance liquid chromatography. Moderate concentrations of PHs activated specialized oil-degrading microorganisms which in turn promoted the efficiency of phytoremediation. Polluted soils planted with B. scoparia also showed a significant reduction in sulfur levels. The potential demonstrated for remediation of petroleum hydrocarbons and sulfur by B. scoparia suggests it may be a useful tool for remediation of arid land soils contaminated with crude oil.