Archives of Current Research International

Petroleum hydrocarbon contamination presents persistent environmental concerns because hydrocarbons can remain in soil and water matrices. This study evaluated post-remediation hydrocarbon concentrations at selected sites in Gokana Local Government Area, Rivers State, Nigeria. Soil samples were collected from a long-term remediated dryland site (LRDL), a pristine dryland control (PDL), a pristine wetland control (PWL), and an unremediated wetland site (URWL). Total hydrocarbon content (THC), total petroleum hydrocarbons (TPH), and polycyclic aromatic hydrocarbons (PAHs) were determined. Data were analysed using one-way analysis of variance, and results were expressed as mean ± standard deviation. The URWL site recorded the highest THC and TPH concentrations, at 297.9 and 223.4 mg/kg, respectively. In comparison, the LRDL site recorded 1.400 mg/kg THC and 1.050 mg/kg TPH, while PDL recorded 0.800 and 0.600 mg/kg, and PWL recorded 4.530 and 3.398 mg/kg, respectively. The URWL site also contained high concentrations of n-C39 (68.67 ppm), n-C38 (36.05 ppm), and n-C9 (29.96 ppm). Total PAH concentration was highest in URWL (1.277 mg/kg), followed by PWL (0.019 mg/kg), LRDL (0.006 mg/kg), and PDL (0.003 mg/kg). The findings indicate that the long-term remediated dryland had hydrocarbon concentrations close to those of the pristine dryland, whereas the unremediated wetland retained substantially higher concentrations. Continued post-remediation monitoring and site-specific management are recommended.