Concentrations, Origin, and Associated Exposure Risk of Polycyclic Aromatic Hydrocarbons in Soil Depths from Selected Petroleum Tank Farms in Western Delta, Nigeria

Abstract

This study determined the background occurrence, distribution, and exposure risks of the sixteen priority polycyclic aromatic hydrocarbons (16-PAHs) in soils from the vicinity of petroleum tank farms in Western Delta, Nigeria. The samples were collected in the fifteen petroleum tank farms at 0–15 cm, 15–30 cm, and 30–45 cm depths. After extraction by ultrasonication with n-hexane/dichloromethane and clean-up in silica gel/alumina packed column. The concentration of PAHs was determined using gas chromatography fitted with mass spectrometry (GC–MS). The Σ16-PAHs ranged from 4.49 to 447.86 mg kg^-1 for all sites and depths. The concentration of the Σ16-PAHs in the samples exceeded the Department of Petroleum Resources (DPR) target values, and 38% depicts PAHs concentrations above the DPR intervention values, this suggests the presence of high molecular weight petroleum products such as diesel and heavy oil, and soils from the tank farms' are polluted with a considerable amount of soils within PAHs. The total cancer risk falls within the low to moderate category. The principal sources of PAHs are petrogenic and low-high-temperature combustion processes. This study provided empirical data on the pollution load, origin, and associated risks of PAHs in soils in some petroleum tank farms. Appropriate clean-up actions are needed to mitigate the accumulation of PAHs in soil and biota and the ecological and human exposure risks in the surrounding aquatic and terrestrial environments.

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Keywords:

• Concentrations
• PAHs
• soil pollution
• exposure risks
• tank farms

Acknowledgments

Thanks to Apex Analytics LTD, 6 Chief Wopara Street, off Market Road, Rumuomasi, Port Harcourt, Nigeria for the laboratory and technical support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author’s contributions

All authors contributed to the development and completion of the study. This study was conceptualized and designed by Onoriode O. Emoyan. All authors were involved in the collection, preparation, and analysis of samples for the determination of PAHs. The compilation and statistical analysis of PAHs results by Onoriode O. Emoyan and Godswill O. Tesi. The first draft of the manuscript was written by Onoriode O. Emoyan, and Godswill O. Tesi. All authors commented on previous versions of the manuscript, and the review and editing of the final manuscript was carried out by Onoriode O. Emoyan. All authors read and approved the final manuscript.

Availability of data and materials

All data generated for this study are included in this article and its Supporting Information.

Additional information

Funding

This study was funded by the authors.