Distribution and Bioaccumulation of Petroleum Hydrocarbon in Tympanotonus fuscatus from Contaminated Coastal Sediments in Rivers State, Nigeria

Background: The Niger Delta region of Nigeria, one of Africa’s largest wetlands and a focal area for hydrocarbon exploitation, plays a significant role in the country’s economy due to its extensive oil and gas reserves. However, decades of petroleum exploration, production, and frequent oil spills have led to widespread environmental degradation and contamination of terrestrial and aquatic ecosystems. Persistent releases of petroleum hydrocarbons have contaminated soils, water bodies, and vegetation, disrupted ecological balance and diminished biodiversity across the region. Aim of the work: This study assessed petroleum hydrocarbon contamination and bioaccumulation in Tympanotonus Fuscatus from coastal sediments in Rivers State, Nigeria, between July and December 2023. Material and methods: The study area lies within the geographical coordinates 4°49′51.9″N 7°02′29.2″E, 4°49′51.9″N 7°02′29.2″E to 4°49′51.9″N 7°02′29.2″E, defining the spatial extent of the sampling locations. Average precipitation for all seasons is 3200 mm. T. Fuscatus var. radula samples were collected randomly. The Bioaccumulation Factor (BAF) was computed. Composite sediment samples were gathered and examined, and TPH levels in sediment were analyzed. Hydrocarbon extraction and analysis for fish was. Gas chromatographic analysis for fish was carried out with Quality assurance and quality control (QA/QC) procedures. Results: Sediment total petroleum hydrocarbons (TPHs) exhibited marked spatial heterogeneity, with the highest concentrations at Station 2 (3.0±0.316 mg/kg). Hydrocarbon accumulation in T. Fuscatus varied among stations, with Station 3 recording the highest mean concentration (1.25±0.06 mg/kg), highlighting both bioavailability and environmental influences. Selective bioaccumulation of specific hydrocarbons was evident, with benzene reaching (0.002±0.001 mg/kg) at Station 2 and n-pentadecane and n-hexadecane displaying bioaccumulation factors (BAFs) up to 520. Human health risk assessment demonstrated that non-carcinogenic risks (Hazard Quotient, HQ, and Hazard Index, HI) were below the threshold of unity for both adults (0.035–0.036) and children (0.082–0.084). However, lifetime carcinogenic risk (CR) estimates ranged from 2.04×10⁻⁵to 2.07×10⁻⁵for adults and 4.76×10⁻⁵to 4.84×10⁻⁵for children, within the USEPA acceptable range but closer to the upper bound for children. Toxicokinetic differences between aromatic hydrocarbons (benzene, toluene, ethylbenzene, xylene) and n-alkanes (C6–C16). Conclusion: The study underscores the need for continued monitoring of hydrocarbon contamination, targeted mitigation strategies, and dietary advisories to protect aquatic ecosystems and local communities reliant on fish consumption, particularly children and subsistence fishers, from cumulative health risks associated with petroleum hydrocarbon exposure.