ABSTRACT
This study assessed the quality index of surface water from Okpare Olomu River. Surface water samples were collected at each location from October 2023 to January 2024. Water physiochemical parameters such as pH, electrical conductivity (EC), organic carbon (OC), moisture content, available phosphorus (P), total nitrogen (N), cation exchange capacity (CEC), sand, silt, clay, colour, turbidity, total dissolved solids (TDS), total suspended solids (TSS), total solids (TS), dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), alkalinity, hardness, chloride (Cl-1 ), potassium (K), sodium (Na+), calcium (Ca), magnesium (Mg), sulphate (SO4), phosphate (PO43), and nitrate (NO3 ) and total nitrogen (N) were analysed using various recommended routine laboratory analysis. Concentrations of heavy metals were determined using Atomic Absorption Spectroscopy. The mean concentration of physicochemical parameters and total hydrocarbon content in water samples were 5.78±0.09 (pH), 20.32±3.61 (EC), 7.47±0.49 (Turbidity), 8.53±3.39 (TDS), 73.25±1.73 (TSS), 81.87±4.95 (TS), 5.59±0.47 (DO), 5.98±1.81 (BOD), 34.65±8.06 (COD), 8.46±1.87 (Alkalinity), 9.96±3.78 (Hardness), 6.15±2.55 (Cl), 1.69±0.55 (K), 1.09±0.20 (Na), 2.16±1.09 (Ca), 0.81±0.36 (Mg), 2.92±0.49 (SO4), 0.42±0.18 (PO4), 2.29±0.46 (NO3), 0.68±0.41 (Nitrogen),1.649±1.26 (Fe), 0.075±0.08 (Cr), 0.028±0.04 (Cd), 0.068±0.06 (Cu), 0.143±0.08 (Zn), 0.013±0.01 (Mn), 0.081±0.11 (Pb) and 3.354±1.26 (THC). The summative water quality index (WQI) observed in stations 1, 2 and 3 were 1113.24, 590.64, and 251.76 and 136.21 respectively and are classified as Grade E making it unsuitable for drinking water purposes. This is attributed to the elevated levels of Fe, Mn, Cr, Cd and Pb in the water. The summative comprehensive pollution index (CPI) observed in stations 1, 2 3 and 4 were 1.67, 2.20, 1.24 and 0.66 respectively. Ranging from slight pollution in station 4 to severe pollution in station 2 and attributed the pollution to elevated levels of heavy metals such as Fe, Cr, Cd and Pb. Overall, the values obtained in this study are however above or below maximum allowable limits (MAL) set by USEPA, WHO/FAO, EGASPIN, and NESREA. This study further buttress the need for the implementation of recommendations for the clean-up of the oil spills in Niger Delta region as the survival of human lives and other living components in this area are threatened
