Particle Size Characteristics, Levels of Heavy Metals and Polycyclic Aromatic Hydrocarbons in Sediments of Major Waterbodies in Owerri, Imo State, Nigeria

Chemical composition of aquatic habitats, including the concentration of chemical contaminants at the aquatic sediments is of great concern to the quality of aquatic environment. A study was carried out to assess variability in particle size distribution (PSD), concentrations of heavy metals (HM) and polycyclic aromatic hydrocarbons (PAHs) across major water bodies in Owerri Municipal. Stratified random sampling technic was employed; the two rivers put together were stratified into eight (8) sampling stations (SS) comprising of three (3) locations along Nworie River (SS1-3) and five (5) locations along Otamiri River (SS4-8). Samples were collected in triplicates. Samples were analyzed in a laboratory, and data generated were subjected to descriptive statistics and analysis of variance using SPSS version 23. Significant means were separated using Duncan Multiple Range Test at 5 % probability level. Results revealed that the sediments vary in PSD; the highest amount of sand (71.8 %), silt (77.6 %), and clay (62.7 %) were observed at SS1, SS4, and SS3, respectively, while the lowest percentage of sand (6.5 %) and clay (20.1 %) were observed at SS3 and (SS1 and 8), respectively. The concentrations of the HM and PAHs varied significantly (P≤0.05); the highest mean concentrations of As, Cd, Cr, Fe, Mn, Ni, Pb, Se, and PAHs were observed at SS4, SS1, SS3, SS1, SS3, SS6, SS1, SS8, and SS1, respectively. Among the various sampling stations, SS1 had the greatest ecological hazard potential to the aquatic ecosystem. Regular monitoring and pollution mitigation strategies are required to reduce pollution and safeguard the environment.