Geochemical Fingerprinting of Oil Spill Sources in the Niger Delta Using Molecular Biomarkers: An Original Forensic Framework

Attribution of individual oil spill events to specific source facilities or formations in the Niger Delta is currently hindered by the lack of a validated forensic geochemical framework capable of distinguishing crude oil types, pipeline condensates, and artisanal refinery products on the basis of molecular biomarker signatures. This study develops an original forensic geochemical framework for oil spill source attribution in the Niger Delta using comprehensive molecular biomarker analysis and multivariate chemometric classification. Reference oil samples were collected from producing wells and storage facilities spanning five different reservoir formations in Delta, Rivers, and Bayelsa states, creating a chemical reference library of one hundred and twelve samples. Environmental oil samples collected from documented spill sites were analysed by gas chromatography-mass spectrometry for diagnostic biomarkers including hopanes, steranes, diasteranes, and aromatic hydrocarbons. A suite of diagnostic ratios was computed and evaluated for source discrimination power using principal component analysis, hierarchical cluster analysis, and linear discriminant analysis. A Bayesian probabilistic matching algorithm was developed to assign posterior probabilities of source identity to unknown spill samples against the reference library. Weathering correction algorithms based on laboratory weathering experiments are incorporated to account for evaporation and biodegradation effects on biomarker ratios in field samples. The validated framework is tested on twelve blind test samples with known sources, achieving correct source attribution in ten of twelve cases. Keywords: oil spill forensics, molecular biomarkers, Niger Delta, source attribution, chemometrics.