ABSTRACT
This study assessed the physicochemical properties and polycyclic aromatic hydrocarbon of surface water from Ossiomo River, Edo State. A total of 36 samples were collected from three sampled stations. Surface water samples were collected at each stations from November 2021 to January 2020. Surface water samples such as pH, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), total solids (TS), dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), hardness, total nitrogen (N), alkalinity, chloride (Cl -1), sulphate (SO4), nitrate (NO3) and phosphate (PO4) were analysed using various recommended routine laboratory analysis. Polycyclic aromatic hydrocarbon (PAH) compounds were analysed using the Gas Chromatography Flame Ionization Detector (GC FID). The mean concentration of physicochemical properties in surface water were 6.17±0.15 (pH), 36.67±5.13 (EC), 19.33±1.15 (TDS), 73.33±86.66 (TSS), 77.11±56.36 (TS), 4.36±0.28 (DO), 1.78±0.19 (BOD), 6.69±1.33 (COD), 1.64±0.25 (Ca), 0.43±0.13 (Mg), 0.96±0.04 (Na), 0.60±0.04 (K), 6.43±0.12 (hardness), 0.00±0.00 (N), 5.06±0.75 (alkalinity), 6.81±1.65 (Cl -), 1.61±0.62 (SO4), 1.05±0.20 (NO3) and 0.04±0.01 (PO4) respectively. Among the physical and chemical properties analysed, pH, Electrical conductivity, Total dissolved solids, Total suspended solids, Total solids, Dissolved Oxygen, Biological Oxygen demand, Calcium, Sodium, Potassium, Hardness, Nitrogen, Alkalinity, Chlorine, Sulphate, Nitrate and Phosphate showed no significant difference (p > 0.05) between the three sampled stations from Ossiomo River while Chemical oxygen demand and Magnesium exhibited a significant difference (p<0.05) between the sampled stations along the stretch of Ossiomo River. The Principal Component Analysis (PCA) showed a cumulative variations of 94.559% of the total variance in the data set. Positive and significant correlations were observed indicating that these elements may have originated from lithogenic and anthropogenic sources. Five PAHs compounds were found at stations 2 in the surface water at very low concentrations in the order; Benzo(a)anthracene > Benzo(b)fluoranthene > Benzo(ghi)perylene > Anthracene > Benzo(a)pyrene respectively while other PAHs compounds were not detected (ND). However, the very low PAHs value detected in station 2 of this study calls for serious pollution concern, as this water body serves as a drinking source to communities living around the river. There is the need for compliance of environmental laws to prevent the river from further deterioration.
