An Analytical Investigation Study of Potential Human Health Risks Caused by Petroleum-contaminated Surface Water Containing Various Toxic Heavy Metals at the Okpoka Creek, Niger-Delta, Nigeria

Abstract

Surface water samples were collected from the Okpoka Creek, Niger-Delta using the grab samples method and were analytically investigated for petroleum contamination. The liquid-liquid extraction of petroleum hydrocarbons was carried out following standard procedures of U.S EPA 3510; 1664 method and ASTM D3695 -95(2013). The US EPA 3005A method was adopted for acid wet digestion (Aqua regia mixture of concentrated HNO3 and HCl  in ratio 1:3) for toxic heavy metal (HMs) determination. Total petroleum hydrocarbons (TPHs) was analytically identified and quantified with the representative extract (sample) using Gas chromatography mass spectrometry detection (GC-MSD) Agilent Technologies 7890A in adherence to the standard analytical method of U.S EPA 8270;625. Atomic absorption spectrophotometer (AAS) Buck Scientific 210VGP in adherence in to the manufacturer’s specifications was employed for HMs. The recorded elevated levels of the TPHs were significantly above the permissible limit of DPR/EGASPIN and HMs were also overwhelmingly above permissible limits of relevant regulatory agencies. The elevated concentrations of these contaminants of concern provided evidences of severe contamination in the study site and severe threats to environment and human health.