Investigating the Effectiveness of Aquatic Plant Species as Bioindicators for Detecting Petroleum Hydrocarbon Pollution in the Marsh Ecosystems of Ogoniland, Niger Delta, Nigeria

The Niger Delta region, particularly Ogoniland, has faced extensive environmental pollution due to petroleum activities, raising concerns about the contamination of aquatic ecosystems. This study aimed to investigate the levels of Total Petroleum Hydrocarbons (TPHs), Polycyclic Aromatic Hydrocarbons (PAHs), and n-Alkanes in four aquatic plant species Eichhornia crassipes, Phragmites karka, Typha domingensis, and Nymphaea lotus from Ogoniland and evaluate their potential as bioindicators for petroleum contamination. Samples of these aquatic plants were collected from the polluted area and analyzed using Soxhlet extraction for TPHs, spectrofluorometry for total petroleum hydrocarbon quantification, and gas chromatography for PAHs and n-Alkanes. The results revealed that Eichhornia crassipes accumulated the highest concentration of TPHs at 18.7 ± 1.2 µg/g dry weight, followed by Typha domingensis (18.1 ± 1.2 µg/g), Phragmites karka (17.5 ± 1.1 µg/g), and Nymphaea lotus (15.8 ± 1.0 µg/g). Similarly, Eichhornia crassipes also showed the highest PAH levels at 112.5 ± 8.4 ng/g, whereas Nymphaea lotus had the lowest PAH concentration at 101.2 ± 7.5 ng/g. The study found a predominance of high molecular weight PAHs and identified a biogenic origin for most n-Alkanes, with Phragmites karka reflecting some anthropogenic influences. These findings suggest that Eichhornia crassipes is the most effective bioindicator for petroleum contamination among the studied species, highlighting the value of aquatic plants in environmental monitoring. Future research should focus on the long-term effects of petroleum pollutants on these plants and assess how seasonal variations might influence contaminant levels.