Assessment of microplastics and associated ecological risk in the Hirakud Reservoir, Odisha, India

Abstract

Microplastic has emerged as a global threat owing to its chronic ubiquity and persistence. Microplastics’ small size expedites their ingestion at each trophic level causing biomagnification and bioaccumulation, which has raised public concerns. The present study isolated, quantified and characterized the abundance, shape, size, color, and chemical composition of the microplastics from water and sediments of the Hirakud Reservoir through a scanning electron microscope and FTIR. The ecological risk associated with the microplastics was assessed using the species sensitivity distribution (SSD) method to derive the Predicted No-Effect Concentration (PNEC) value and risk quotient (RQ). The abundance of microplastics in the surface water and sediments of the Hirakud Reservoir was estimated at 82–89 particles/L and 159–163 particles/kg, respectively. Fiber-shaped microplastics dominated both surface water (46.21%) and sediment samples (44.86%). Small-sized microplastics (53–300 μm) prevailed in all samples. Color delineation exhibited an abundance of transparent microplastics. Chemical characterization indicated the dominance of polypropylene (38%), followed by high-density polyethylene, low-density polyethylene, and polystyrene. The calculated PNEC value was 3,954 particles/m3, and the RQ was estimated to be 0.02073–0.04122 indicating negligible ecological risk to freshwater species in all the sampling sites. HIGHLIGHTS Microplastics were detected in all the sampling sites.; Transparent and fibrous microplastics dominated all sampling sites.; Aquaculture and tourism were found to be the possible contributors to microplastics.; FTIR analysis showed a higher abundance of polypropylene microplastics in the reservoir.; The calculated Risk Quotient indicated negligible ecological risk.;

Keywords

• freshwater pollution
• hirakud reservoir
• microplastics
• risk assessment