Distribution and characterization of microplastics in Narmada River: Insights from differently impacted anthropogenic zones of upper and middle basin in Central India

The Narmada River is a vital water source for irrigation, drinking, and hydroelectric projects in India. It passes through rural, agricultural, semi urban, and tourist intensive areas, making it vulnerable to anthropogenic pressure. We proposed that the abundance of microplastics (MP) and the diversity of polymers vary across these anthropogenically disturbed regions, with tourist and semi-urban contributing more than rural agriculture regions. To test this, we assessed the upper and middle river basin (in surface water and sediments). Morphological characterisation (shape, size, colour) was performed using a stereomicroscope and particle size analyser, while chemical composition was determined by ATR-FTIR and µFTIR. The average concentration of MPs is 4738 ± 5303 particles/m³ in surface water and 290071 ± 199929 particles/m³ in sediments, respectively. Nineteen distinct polymers including hazardous polymers like polyurethane and poly vinyl chloride were identified revealing complex chemical footprint. In surface water, polypropylene, polyethylene, and polyethylene terephthalate were dominant, whereas in sediments, polyethylene and polyethylene terephthalate were more prevalent. Fibers dominated surface water, while fragments dominated sediments. Additives like dibutyl sebacate and ethyl hexyl epoxy soyate were also identified. Polymer hazard index (PHI) and potential ecological risk index (PERI) also predicted the risks imposed by the hazardous polymers. Tourist locations with anthropogenic disturbances have a higher MP abundance in surface water, while both semi-urban and tourist locations contribute to MP pollution in sediments. These findings demonstrate that anthropogenic activities strongly influence MP pollution in the Narmada River and highlight the urgent need for region-specific management strategies.