New Delhi: Microplastics have been detected in all freshwater fish species examined from Yamuna. Fish from the Delhi stretch have significantly higher contamination than those from upstream areas, a study by researchers from University of Delhi has revealed.Microplastics are small plastic particles less than 5 mm in size. The study assessed 220 fish representing 12 species collected from four locations along the river—Yamuna Nagar and Karnal in Haryana and Sur Ghat and Sonia Vihar in Delhi.“Microplastics were detected in all examined species, confirming extensive distribution across the river ecosystem. A total of 1,678 microplastics were recovered, with significantly higher abundance in fish from the highly urban Delhi stretch than in those from upstream regions. The findings identify the Delhi stretch of Yamuna as a high microplastic contamination zone and highlight the combined influence of urban pollution and fish ecology on microplastic bioaccumulation,” said the study.The downstream stretches of Delhi (Sonia Vihar and Surghat) showed the greatest microplastic loads, contributing a major proportion of the total microplastic detected, whereas upstream sites (Karnal and Yamuna Nagar, Haryana) recorded lower abundances. “This spatial gradient reflects the influences of urban wastewater discharge, textile effluents and increased suspended particulate load in Delhi’s metropolitan section,” the study added.The research titled “Environmental drivers and bioaccumulation pathways of microplastics in freshwater fish from the river Yamuna, India” revealed that the highest species-specific microplastic burden was found in the omnivorous Oreochromis niloticus (tilapia) from Sonia Vihar, where researchers recovered 436 microplastic particles, while the carnivorous Xenentodon cancila from Karnal recorded the lowest accumulation at 37 particles.The study found that the gastrointestinal tract contained the highest number of microplastics (751 particles), followed by the gills (605) and muscle tissues (322). According to the researchers, this indicates that ingestion is the primary route of exposure, while the presence of microplastics in muscle tissue suggests possible translocation to other organs.“The detection of microplastics in muscle tissues further highlights direct exposure risks for human consumers relying on these fish species as a protein source,” said the research.The analysis identified 10 diverse polymers, with polyethylene (24%) and polypropylene (21%) together accounting for nearly half of the identified particles. The Polymer Hazard Index classified the recovered microplastic mixture as Category IV, indicating a high ecological hazard.
