EN
The assessment of total petroleum hydrocarbons (TPH) status as well as the aliphatic profiles of sediments from the Okpu and Iyiowa-Odekpe segments of the River Niger in South-Eastern Nigeria was conducted during the year 2021 – 2022. Composites samples taken from sediments at five (5) different locations (ST-A, ST-B, ST-C, ST-D, & ST-E) for the months of June, September, December, and February, were extracted with dichloromethane (DCM) using soxhlet extractor followed by a silica gel clean up and fractionation into aliphatic and aromatic fractions. Analysis of aliphatic fraction (Total Aliphatic Hydrocarbons –TAH - and aliphatic components) were done with gas chromatography-flame ionization detector (GC-FID); while the polycyclic aromatic hydrocarbons (PAHs) were determined with gas chromatography-mass spectrometry (GC-MS). The summations of TAHs and PAHs gave the TPHs concentrations that ranged from 108.04 – 1091.46mg/Kg with a mean of 440.0234 ± 54.78mg/Kg. The mean value for the raining season (515.10±281.73 mg/Kg) was significantly higher than that of the dry season (364.94 ± 205.54 mg/Kg). The range of values were also much higher than the Nigerian Department of Petroleum Resources (DPR) target value of 50mg/Kg but considerably much lower than the intervention value (5,000mg/Kg) set by the same body. Source diagnostic indices of aliphatic hydrocarbons gave range of: even to odd numbered n-alkane ratio (0.7183 – 1.7184), carbon preference index – CPI (0.65041 – 1.4520), sum of low molecular weight to high molecular weight n-alkane (1.0559 – 8.8077), nC31/nC19 (0.16867 – 1.1461), sum of long chain hydrocarbons to short chain hydrocarbons (0.1686 – 1.1470), and pristane/phytane ratio (0.6523 – 2.5284); suggesting that the TPHs in sediments were from mixed origin – anthropogenic and biogenic. Inputs from biogenic sources were however, dominated by marine sources. Developmental plans and actions that will reduce these anthropogenic inputs are necessary to protect the aquatic lives and sustain public health.