Molecular Fingerprinting and Source Apportionment of Petroleum Hydrocarbons in Sediments of the Bonny Estuary, Rivers State, South South Nigeria

The Bonny Estuary serves as both a major petroleum export corridor and a critical ecosystem supporting artisanal fisheries and coastal livelihoods, yet the sources and extent of hydrocarbon contamination in its sediments are inadequately characterised using modern molecular analytical approaches. This study performs molecular fingerprinting and source apportionment of total petroleum hydrocarbons, polycyclic aromatic hydrocarbons, and petroleum biomarker compounds in surface sediments from twelve stations across the Bonny Estuary, Rivers State, South South Nigeria. Sediment samples are extracted using pressurised liquid extraction and analysed by gas chromatography-flame ionisation detection for total petroleum hydrocarbons and resolved and unresolved complex mixtures, and by gas chromatography-mass spectrometry for polycyclic aromatic hydrocarbon congeners and hopane and sterane biomarker compounds. Diagnostic ratios including fluoranthene to pyrene, phenanthrene to anthracene, chrysene to benzo[a]pyrene, and pristane to phytane are used for petrogenic versus pyrogenic source differentiation. Hopane biomarker fingerprinting is applied for crude oil source identification and weathering assessment. Positive matrix factorisation receptor modelling is applied to polycyclic aromatic hydrocarbon and biomarker data to quantify relative contributions from vessel traffic, pipeline spills, and combustion sources. Ecological risk assessment uses sediment quality guidelines to calculate mean probable effect quotients for individual polycyclic aromatic hydrocarbons. Findings provide the first comprehensive molecular-level contamination profile of this economically critical estuary and support the Niger Delta Environmental Survey's ongoing remediation documentation. Keywords: petroleum hydrocarbons, sediment contamination, molecular fingerprinting, Bonny Estuary, source apportionment