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Characterization of weathered microplastics in freshwater and fish from the Central Himalayas

Environmental Monitoring and Assessment 2026
Ganesh Chiranji, Syed Talia Mushtaq, Kishor Kunal, Tasaduq Hussain Shah, Farooz Ahmad Bhat, Iqbal Jeelani Bhat, Imtiyaz Qayoom

Summary

Even remote, high-altitude lakes and rivers in the Himalayas aren't safe from plastic pollution—researchers found tiny plastic fibers (mostly from things like clothing and packaging) in both the water and the fish living there, with fish from one lake showing especially high levels. Since these fish are commonly eaten, this suggests microplastics can make their way from far-flung freshwater sources into our food, and the worn, cracked surfaces of these plastic bits may make it easier for them to absorb other harmful substances before reaching our plates.

Study Type Environmental

Microplastic (MP) contamination has emerged as a pervasive environmental issue globally, yet information from high-altitude Himalayan freshwater ecosystems remains scarce. This study combines spatial distribution analysis with morphological characterization (SEM-EDS) to assess polymer weathering of microplastics in surface waters and the freshwater fish Tor putitora (Golden Mahseer) from three Himalayan systems of Uttarakhand, India-Bhimtal Lake, the Ladhiya River (Chalthi), and Pancheshwar (Saryu-Kali confluence). Surface water (100 L/site) and fish (n = 30/site) samples were processed following standardized digestion and filtration protocols. Representative MP particles from water and fish tissues were characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS). Microplastics were detected in all samples, ranging from 2.4 ± 0.8 particles L⁻ in water to 3.2 ± 1.1 particles g⁻ in fish tissues. Fish from Bhimtal Lake exhibited the highest loads (6.8 ± 0.4 items/individual). Fibers dominated (74-82%), primarily black and blue, with most particles < 500 µm. FTIR analysis identified five major polymer types-nylon, polyethylene, polypropylene, polyethylene terephthalate, and polystyrene while SEM-EDS revealed surface cracking, pitting, and elevated O and Si, indicating oxidative degradation and inorganic adsorption. The integrated spatial-morphological approach demonstrates polymer weathering signatures and trophic transfer pathways in Himalayan rivers, identifying T. putitora as a sentinel species for inland plastic pollution. These findings provide a mechanistic understanding of microplastic transformation and highlight the urgent need for watershed-scale interventions to mitigate plastic contamination in high-altitude freshwater ecosystems. Spatial variation across sites was linked with polymer-specific surface degradation patterns to infer environmental transformation processes.

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