Assessment of Heavy Metal and Polycyclic Aromatic Hydrocarbon (PAH) Levels in Drilling Fluids and Effluents from Niger Delta Oil Fields

The Niger Delta region, located in southern Nigeria, West Africa, is a significant hub for oil production. However, drilling activities in this region generate substantial amounts of waste effluents, posing environmental and health risks. This study investigates the concentrations of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in drilling fluids and their effluents from Niger Delta oilfields. A total of 14 samples of produced water were collected from seven different oil drilling locations and analyzed for heavy metals and PAHs using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Gas Chromatography-Mass Spectrometry (GC-MS), respectively. The results revealed elevated levels of some heavy metals and PAHs, exceeding international standards. Specifically, the mean concentrations of Aluminum (Al) (0.522 mg/L), Boron (B) (1.004 mg/L), and Iron (Fe) (2.359 mg/L) exceeded the WHO’s acceptable threshold limits for metals in water. In contrast, Barium (Ba), Cobalt (Co), Strontium (Sr), and Zinc (Zn) were within acceptable limits. Notably, some heavy metals were detected in the effluents but not in the drilling fluid. These included Beryllium (Be) (1.365 mg/L), Chromium (Cr) (0.094 mg/L), Manganese (Mn) (0.085 mg/L), and Thallium (Tl) (0.016 mg/L). Conversely, Antimony (Sb), Arsenic (As), Cadmium (Cd), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Titanium (Ti), and Vanadium (V) were not detected in either the drilling fluid or the effluents. The analysis of PAHs in produced water samples revealed concentrations that exceeded EU standards by a significant margin, whereas the control sample showed relatively low concentrations. This study highlights the substantial environmental and health risks associated with heavy metal and PAH pollution in Niger Delta oilfields. These risks include potential harm to aquatic life, soil and groundwater contamination, and adverse human health effects. The findings emphasize the need for enhanced regulatory measures, improved waste management practices, and the adoption of eco-friendly drilling fluid alternatives. This study contributes to a better understanding of the impact of heavy metal and PAH pollution in Niger Delta oilfields and provides valuable insights for policymakers, oil companies, and stakeholders on the necessity of sustainable environmental management practices. Recommendations include regular monitoring, effective waste disposal strategies, and personnel training programs to mitigate heavy metal and PAH pollution in the region.