Characterization and risk assessment of microplastics pollution in Mohamaya Lake, Bangladesh

Microplastics (MPs) have recently gained attention as emerging environmental contaminants, yet knowledge of their distribution, sources, and risks in freshwater lakes remains limited. This study examined the occurrence and risk of MPs in water and sediment samples from eight locations in Mohamaya Lake (Bangladesh) collected in April and May 2023. MPs were identified using stereomicroscopy and FTIR, revealing concentrations of 20-95 particles/L in water and 550-1900 particles/kg (d.w.) in sediment, with mean values of 50.62 ± 9.95 particles/L and 1068.75 ± 521.49 particles/kg (d.w.). Dominant MPs were blue fibers, 0-0.5 mm in size, with HDPE, PET and LDPE as the most common polymers. This study used four indices (nemerow pollution index-NPI, contamination factor-CF, pollution load index-PLI, and polymer hazard index-PHI) to assess MP pollution, revealing light to high contamination levels. While NPI indicated light pollution, CF, PLI, and PHI highlighted areas of moderate to high risk, with certain polymers showing high to extreme toxicity. This study deepens understanding of MP contamination in Bangladesh's freshwater lakes, underscoring the need for research on ecotoxicology, regulation, and associated challenges.