Determination of microplastics and physicochemical parameters in Nwaorie River, Owerri Municipal, Imo State

Microplastic pollution has emerged as a major environmental concern due to its persistence, ecological toxicity, and potential risks to aquatic organisms and human health. This study investigated the occurrence of microplastics and evaluated the physicochemical properties of water samples obtained from Nwaorie River, Owerri Municipal, Imo State, Nigeria. Water samples were collected from upstream, midstream, and downstream regions of the river using standard environmental sampling procedures. Physicochemical parameters including pH, conductivity, turbidity, temperature, hardness, alkalinity, acidity, dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), nitrate, phosphate, chloride, sulphate, and total coliform count were determined using standard analytical methods. Microplastic particles were identified using light microscopy and categorized into microfragments, microfibres, and microbeads. The results showed conductivity (144.01 ± 2.16 µs/cm), hardness (148.36 ± 0.23 mg/L), acidity (43.55 ± 0.64 mg/L), BOD (123.4 ± 1.56 mg/L), COD (123.43 ± 1.59 mg/L), phosphate (8.72 ± 0.42 mg/L), and total coliform count ((1.43 ± 0.04) × 10² cfu/mL), all of which exceeded WHO/EU permissible limits. Conversely, turbidity, temperature, nitrate, chloride, sulphate, and total suspended solids remained within acceptable regulatory standards. Microplastic particles including microfragments, microfibres, and microbeads were detected across upstream, midstream, and downstream regions of the river, indicating widespread plastic contamination within the aquatic ecosystem. The occurrence of microplastics and elevated pollution indicators suggests significant anthropogenic influence arising from sewage discharge, urban runoff, domestic activities, and indiscriminate disposal of plastic wastes around the river environment. The findings from this study highlight the growing environmental burden of microplastic pollution and deteriorating water quality within Nwaorie River, emphasizing the need for improved waste management practices, environmental monitoring, and pollution control measures to protect freshwater ecosystems and public health.