Contamination of soil and air by Polycyclic Aromatic Hydrocarbon (PAH) as a result of oil and gas production activities in Akwa Ibom State, Nigeria

Asuquo, Affiong Lovlyn (2023). Contamination of soil and air by Polycyclic Aromatic Hydrocarbon (PAH) as a result of oil and gas production activities in Akwa Ibom State, Nigeria. University of Birmingham. Ph.D.

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Abstract

Petroleum exploitation and production have enormous economic value globally, but with potential attendant potential negative impacts on the environment. One such impact is the emission of Polycyclic Aromatic Hydrocarbons (PAH) that are known for their carcinogenic and other potential toxic effects.
In this study, the concentrations, profile, and human exposure to fourteen PAH were studied in soil and air collected in the vicinity of a rural oil and gas exploration site in Akwa Ibom State, Niger Delta, Nigeria. Spatial and seasonal trends were also investigated. Soil and air samples were collected in both the wet and dry season at a variety of locations impacted by different steps in the process of oil and gas exploration and production.
Soil samples were extracted with a validated ultra-sonication method, with air samples extracted via an enhanced sonication method connected to a reflux column. Sample analysis was conducted via GC-MS.
The results revealed that \Sigma14PAH concentrations in air and soil were significantly higher at operational locations compared with those collected from non-operational locations (such as workers’ residences). PAH concentrations in soil decreased with increasing distance from activity locations, underscoring the importance of oil and gas activities. Analysis of variance indicated significantly higher (p <0.05) PAH concentrations in soil at some locations. A similar significant difference between sites for air was not observed, likely due to low sample numbers.
Average concentrations of \Sigma14PAH were higher in the dry season than in the wet season for both soil and air. Concentrations were significantly higher (p<0.05) between the wet and dry season at some locations for soil and air samples.
Concentrations of 3-4 ring PAH were predominant in both wet and dry seasons for soil and air samples in all locations. Comparing the profiles of PAH found in this study with those reported for other oil and gas impacted studies, suggests the influence of oil and gas production activities.
The carcinogenicity and relative importance of adult exposure through inhalation of air and ingestion of soil were evaluated in terms of benzo[a]pyrene equivalents. Exposure to soil via ingestion of soil particles was higher than via air inhalation. Generally, estimated cancer risks of exposure via soil ingestion of soil particle and air inhalation were within levels considered acceptable. To our knowledge, this is the first study in Nigeria where PAH have been investigated in the environment at locations in the vicinity of different oil and gas exploration field in both the wet and dry seasons.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):