Professional Assessment of Phytoremediation Potential of Wetland Plants in Oil-Contaminated Freshwater Habitats of the Niger Delta

Oil spill contamination of freshwater habitats in the Niger Delta continues to devastate aquatic and riparian plant communities, and professional evaluation of indigenous wetland plant species for phytoremediation presents a cost-effective biological treatment option. This study conducted a professional assessment of the phytoremediation potential of four indigenous wetland macrophytes: Phragmites australis, Typha australis, Eichhornia crassipes, and Nymphaea lotus, in freshwater habitats contaminated by crude oil in Bayelsa and Delta States. Field sites with documented crude oil contamination history were selected in partnership with the National Oil Spill Detection and Response Agency. Plant tissue and water samples were analysed for total petroleum hydrocarbons, heavy metals (lead, cadmium, zinc), and biological oxygen demand. Bioconcentration factors, translocation factors, and petroleum hydrocarbon removal efficiency were calculated from paired contaminated and clean site measurements. Eichhornia crassipes showed the highest total petroleum hydrocarbon removal efficiency from surface water (68% reduction in planted mesocosms over 8 weeks). Phragmites australis demonstrated superior heavy metal translocation from root to shoot tissue (translocation factor greater than 1.2 for zinc and lead). Typha australis showed effective total petroleum hydrocarbon reduction in sediment (42% decline). None of the four species alone provided complete remediation. The study recommends a polyculture phytoremediation system combining Eichhornia and Phragmites as the most effective biological intervention for Niger Delta freshwater oil contamination, with an implementation road map for the National Oil Spill Detection and Response Agency.

Keywords: phytoremediation, wetland plants, oil contamination, Niger Delta, bioconcentration factor