Risk Assessment of Polycyclic Aromatic Hydrocarbons and Total Petroleum Hydrocarbons in Oilfield Produced Water and Sea Water at Gulf of Guinea Oilfield, Nigeria

Physiochemical and health risk assessment was conducted on seawater and oilfield produced water collected at Gulf of Guinea Oilfield Location, Nigeria. Analytical parameters such as pH, conductivity, dissolved oxygen, salinity and total dissolved solids were determined, while polycyclic aromatic hydrocarbons (PAHs) and total petroleum was detected and evaluated concentration using gas chromatography-flame ionization detector (GIC-FID). Baseline assessment showed that pH was basic (alkaline), conductivity, salinity, and total dissolved was low indicating less reactive ions, dissolved oxygen was okay across water source. Concentration of PAHs and TPHs results showed that oilfield produced water was highest compared to seawater (seaboard and portside), which was low. Carbon preference index (CPI) conducted on TPHs showed that TPHs had phytoplankton and man-made contribution in chemical composition. Risk assessment conducted on PAHs showed that non-carcinogenic assessment was highest in causative impact compared to carcinogenic assessment, as inhalation exposure was a major contribution less than ingestion (oral) and dermal. Risk assessment conduced on aliphatic and aromatic TPHs showed that carcinogenic assessment had high impact via aromatic than aliphatic while non-carcinogenic assessment had high impact via aliphatic than aromatic. Exposure pathway from risk assessment of PAHs and TPHs showed that inhalation had high carcinogenic and non-carcinogenic health impact compared to dermal and ingestion pathways. Specific care must be taken into consideration when working in an offshore environment as inhalation of these pollutants can cause respiratory and tumours related health issues over a prolong period from oilfield produced water compared to seawater portside and starboard.