Characterization of Macro Litter and Microplastics Abundance in the Ogunpa River, Ibadan: Intimation for Solid Waste Management and Environmental Policy

This study characterized macro litter and microplastics abundance in the Ogunpa River with the intimation for solid waste management and environmental policy. Types of plastics and anthropogenic activities around the sampling points were observed using an observational checklist. Water samples were collected from five sampling locations along Ogunpa River for eight weeks during the wet season while particulate fractions of plastic litter and water quality were determined using standard procedures. Water quality was compared with the limits recommended by World Health Organization (WHO) and National Environmental Standards and Regulations Enforcement Agency (NESREA). Data were analysed using descriptive statistics and Pearson Correlation at p<0.05. Field observations revealed that indiscriminate disposal of solid wastes including plastics led to the high rate of plastic pollution in the river. A total of 3,569 macro litter and plastics were identified and categorized as: plastics (70%), metal (7%), paper/cardboard (5%), rags (4%), rubber (3%), glass/ceramics (4%), medical and agro-based waste (4%) and wood (3%). The mean microplastic was 45.0±0.8 particles/L (range = 32 to 60 particles/L) while the most common shapes found were fibers and fragments. The major polymer identified were polyethylene, polystyrene, polyester, nylon, and polypropylene. Total Suspended Solids (mg/L) and Nitrate (mg/L) values were higher than the recommended limit by NESREA and WHO. A significant positive correlation existed between microplastic concentration in water and Total Suspended Solids. Microplastics were found in high concentration along Ogunpa River and human activities along the river could serve as a source of microplastic pollution. It is essential to raise public awareness of waste disposal and implement stricter waste management policies at the local communities.