Assessing the Hydrocarbon Tolerance and Phytoremediation Trait of Ricinus communis L. in Polycyclic Aromatic Hydrocarbon Spiked Soils

International Journal of Chemistry | Vol. 4, No. 5, May 2013 | pp. 33–40

DOI: 10.46882/2013/IJC/000056

Article Type: Original Research Paper

Title: Assessing the Hydrocarbon Tolerance and Phytoremediation Trait of Ricinus communis L. in Polycyclic Aromatic Hydrocarbon Spiked Soils

Names of Authors: O. F. Olawal¹, G. de Metru²*

Authors’ Affiliations:
¹Department of Plant Biology, University of Ilorin, Ilorin, Nigeria.
²Department of Plant Sciences, Wageningen University, Wageningen, Netherlands.

Abstract: Persistent organic pollutants like polycyclic aromatic hydrocarbons (PAHs) accumulate inside industrial soil sub-surfaces, requiring cost-effective vegetative extraction strategies. This controlled study investigates the growth kinetics and remediation efficiency of Ricinus communis L. (Castor bean) cultivated in soils artificially spiked with varying concentrations of phenanthrene (100 to 500 mg/kg) and pyrene (50 to 250 mg/kg). Plant structural indices, remaining soil PAH concentrations, and root zone microbial populations were quantified over a 90-day developmental period. R. communis demonstrated strong physiological tolerance, maintaining high root-to-shoot biomass ratios across all phenanthrene loading levels. High-Performance Liquid Chromatography (HPLC) profiling showed a 78.4% reduction in soil phenanthrene and a 62.5% reduction in pyrene concentrations within the rhizosphere of cultivated systems, compared to minimal attenuation in unplanted controls. Soil microbiological testing revealed a five-fold expansion of heterotrophic degradation bacteria within the castor root matrix. This confirms that root exudates actively stimulate microbial proliferation, accelerating the degradation of complex polycyclic aromatic structures in contaminated industrial terrains.

Keywords: Ricinus communis; Phenanthrene; Pyrene; Soil phytoremediation; Rhizosphere effect; Microbial degradation

Manuscript Timeline: Received: September 02, 2012; Revised: October 12, 2012; Accepted: November 05, 2012; Published: May 02, 2013.

Citation: Olawal, O. F., & de Metru, G. (2013). Assessing the Hydrocarbon Tolerance and Phytoremediation Trait of Ricinus communis L. in Polycyclic Aromatic Hydrocarbon Spiked Soils. International Journal of Chemistry, 4(5), 33–40.

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