Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in sediment cores of
the microtidal coastline of Lagos lagoon were investigated for the occurrence, sources and depositional
contamination history. Sediment core samples were collected using the Wildco @ hand corer (50 cm)
SS kit and extracted using a 40 mL mixture of hexane and acetone (1:1), and cleaned-up using 10 mm
ID chromatographic column before the concentration of aliquots. In this investigation, 16 US EPA
priority PAHs and PCB congeners were analysed in aliquots of sediment cores using Agilent 7820A
gas chromatograph coupled to a 5975C inert mass spectrometer (with triple-axis detector) with an
electron-impact source. PAHs and PCBs were detected at varying concentrations across the 50 cm depth
of each sediment core. The total PAH concentrations ranged from 1.43–5.90 mg/kg, and were more
widely distributed than the total PCBs. The total PCB concentrations ranged from BDL – 6.41 mg/kg.
The PAH diagnostic ratios used identified the sources of the PAHs as pyrogenic rather than petrogenic.
About 52% of the samples had concentrations above the ERM limit for total PCBs, suggesting that
adverse effects on biota may occur in the long term. In general, the PAHs and PCBs concentrations
detected in sediment cores of the Lagos lagoonal system may pose a considerable ecotoxicological risk
to estuarine organisms
