ABSTRACT
Sediments of rivers receiving industrial and urban effluents are often polluted, and this has prompted investigation. This study assessed the physicochemical properties and heavy metal concentration of sediments from Warri River. Nine Sediment samples were collected from January 2022 to March 2022. Sediment samples such as pH, electrical conductivity (EC), total organic carbon (TOC), total nitrogen (N), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), total hydrocarbon content (THC), sand, silt and clay were analysed using various recommended routine laboratory analysis. The concentration of Iron (Fe), Lead (Pb), Chromium (Cr), Cadmium (Cd), Copper (Cu), Zinc (Zn), Mercury (Hg), Arsenic (As), and Manganese (Mn) were determined using Atomic Absorption Spectrophotometer. The results of the physicochemical properties in sediments such as pH, Electrical conductivity, organic carbon and organic matter content showed a highly significant difference (p<0.01) between the sampled stations from Warri River, total nitrogen and silt showed a significant difference (p<0.05) while sand and clay showed no significant difference (p >0.05) between the three sampled locations from Warri River. Heavy metals such as Fe, Pb Cr, Cd, Cu, Zn, Mn and total hydrocarbon content (THC) in sediments from Warri River were 86.27±7.99 mg/kg, 0.00±0.00 mg/kg, 0.78±0.16 mg/kg, 0.00±0.00 mg/kg, 10.59±2.06 mg/kg, 38.85±11.87 mg/kg, 2.67±2.80 mg/kg, 34.33±3.38 mg/kg for Agbaro (station 1), 508.33±9.80 mg/kg, 0.53±0.15 mg/kg, 2.23±0.16 mg/kg, 0.08±0.08 mg/kg, 55.71±26.11 mg/kg, 323.21±57.12 mg/kg, 49.87±4.56 mg/kg, 230.65±66.28 mg/kg for Ubeji (station 2) and 775.41 ±217.82 mg/kg, 0.47 ±0.20 mg/kg, 3.20±1.21 mg/kg, 0.12±0.13 mg/kg, 66.93±38.52 mg/kg, 374.85±101.67 mg/kg, 64.99±12.38 mg/kg, 59.38±37.27 mg/kg for Udu (station 3) respectively. Heavy metal content such as Manganese (Mn) showed a highly significant difference (p<0.01) between the sampled stations from Warri River, Iron (Fe), Lead (Pb), Chromium (Cr), Copper (Cu), Zinc (Zn) and Total hydrocarbon content (THC) showed a significant difference (p<0.05) while Cadmium (Cd) showed no significant difference (p >0.05) between the three sampled locations from Warri River. Mercury (Hg) and Arsenic (As) were not detected (ND) in bottom sediments from Warri River. The result showed that the concentration of heavy metal were in the following decreasing order: Fe > Zn > Cu > Mn > Cr > Pb > Cd. Heavy metals in sediments exhibited positive and significant correlation with each other as well as with silt and clay. Heavy metal levels in the sediments of the river showed an elevated concentration of all the metals especially at Ubeji (station 2) and Udu (station 3). This is a pointer to the fact that there is unregulated discharge of contaminated effluent into the natural receptor of Warri River without prior treatment by industries and communities within the study area. Efforts should be made by regulating and enforcement agencies in carrying out their duties of monitoring and compliance of the various industries with established effluent limitation guidelines to achieve a cleaner environment in Nigeria.
