Assessment of pollution from produced water discharges in seawater and sediments in offshore, Niger Delta

Abstract

This paper assesses the pollution effects of produced water discharges in seawater and sediments offshore, Niger Delta. Twenty (20) seawater samples were analyzed for their physicochemical properties (i.e., hydrocarbon content, heavy metals and other inorganic constituents), while twenty (20) sediment samples were analyzed and assessed for heavy metals and organic hydrocarbon constituents of produced water [e.g., polycyclic aromatic hydrocarbon (PAH), benzene, toluene, ethyl benzene, xylene (BTEX), phenols and total petroleum hydrocarbon (TPH)]. Principal component and cluster analyses, index of geoaccumulation (Igeo) and pollution load index (PLI) were used to infer the source, extent of pollution and distribution of these contaminants. Results show that the offshore waters were contaminated with TPH, nitrite, sulfate, phosphate, nickel and zinc in the dry season, whereas benzene, toluene, ethyl benzene, xylene (BTEX), polycyclic aromatic hydrocarbon (PAH), cobalt, nitrite, total nitrogen, sulfate, phosphate and zinc were the contaminants in the wet season. The sediments were also contaminated by barium, chromium, copper, iron, nickel, lead, vanadium, zinc, petroleum hydrocarbon in the dry season and by benzene, toluene, ethyl benzene, xylene (BTEX), polycyclic aromatic hydrocarbon (PAH), phenols, arsenic, cadmium, chromium, copper, iron, nickel, lead, vanadium, zinc with total petroleum hydrocarbon (TPH) in the wet season. Based on these findings, it is clear that the composition and quality of seawater and sediments offshore are being altered by hydrocarbon constituents and heavy metals from produced water discharges.