Quantification of Polycyclic Aromatic Hydrocarbons (PAHs) in Soil Adjacent to the Ogini Flow Station Associated Gas Flare, Delta State, Nigeria

Abstract

Gas flaring, a common practice in the oil and gas industry, contributes to
environmental pollution through the release of pollutants, including polycyclic
aromatic hydrocarbons (PAHs). The PAHs levels in soil adjacent to the gas flare
in the Ogini flow station were evaluated. The soil samples were analysed using gas
chromatography-mass spectrometry (GC-MS) for the determination of 16 PAHs
USEPA priority pollutant. The research findings show that the most common
contaminant among the 16 priority PAH compounds tested was
benzo(g,h,i)perylene with a mean concentration of 39.58 mg/kg at the topsoil layer,
followed by indeno(1,2,3-cd)pyrene with a mean concentration of 36.87 mg/kg.
However, the samples collected at the shorter distance to gas flare areas (STN 1 to
STN 3) recorded high concentrations of PAHs levels in the soil. The values
recorded at these stations were above the US EPA Integrated Risk Information
System (IRIS) and the intervention value of polluted soil by the Environmental
Guidelines and Standards for the Petroleum Industry in Nigeria (EGASPIN). The
texture of soil samples in these areas plays a significant role in the retention of
PAHs pollutants, as demonstrated at station three (200 m), where total PAHs were
significantly high at the topsoil (0–15 cm) due to the sandy-clay-loam texture of the
soil, with total PAHs of 278.50 mg/kg and drift drastically to 7.20 mg/kg at the
bottom soil (15–30 cm) of loam sand texture, respectively. Hence, the Niger Delta
environment needs holistic monitoring of PAHs emissions to prevent negative
environmental impacts.