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Environmental Drivers and Bioaccumulation Pathways of Microplastics in Freshwater Fish from the River Yamuna, India

Microplastics 2026
Sneha Siwach, Padma Dolkar, Atul Yadav, Apoorva Atri, Meenu Chaurasia, Pankaj Yadav, Themchuirin L., Sonia Nongmaithem, Vyakhya Singh, Aviral Singh, Ram Krishan Negi

Summary

Scientists found tiny plastic particles (microplastics) in every single fish they tested from India's Yamuna River, with the most pollution found in fish from heavily urban areas near Delhi—and even in fish muscle tissue, the part people actually eat. This matters because it shows plastic pollution is working its way through the food chain and directly into fish that end up on dinner plates, raising concerns about how much plastic we might be consuming when we eat freshwater fish from polluted rivers.

Polymers
Study Type Environmental

Microplastic (MP) contamination is an emerging threat to aquatic ecosystems. However, species-specific bioaccumulation patterns across trophic guilds in tropical river ecosystems remain scarcely understood. This study assessed the occurrence, organ-level distribution, polymer composition, and ecological risk of MPs in 220 fish representing 12 species, spanning across multiple trophic guilds, sampled from four sites along a pollution gradient of the river Yamuna, India. MPs were detected in all examined species, confirming extensive distribution across the river ecosystem. A total 1678 MPs were recovered, with significantly higher abundance in fish from the highly urban Delhi stretch than in those from upstream regions (Kruskal–Wallis, H = 11.03, p = 0.011). The highest species-specific MP load was recorded in omnivorous Oreochromis niloticus from Sonia Vihar (436 MPs), whereas the carnivorous species Xenentodon cancila exhibited the lowest accumulation (37 MPs). Surface- and mid-water herbivores and omnivores accumulated more MPs than benthic carnivores and detritivores. Nonetheless, spatial pollution gradients exerted a stronger influence on MP accumulation, compared to trophic guilds. The gastrointestinal tract exhibited the highest MP abundance (751 MP particles), followed by gills (605) and muscle tissues (322), confirming ingestion as primary uptake route, and suggesting possible tissue translocation. Fibers dominated in the assemblage (77.8%), while transparent (44%) and blue (19.5%) were most abundant colors. ATR–FTIR analysis confirmed 10 diverse polymers, with polyethylene (≈24%) and polypropylene (≈21%) together accounting for nearly half of the identified particles. The Polymer Hazard Index analysis classified the recovered MP mix as Category IV (high ecological hazard). These findings identify the Delhi stretch of the Yamuna as a high MP contamination zone and highlight the combined influence of urban pollution and fish ecology on MP bioaccumulation.

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