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First evidence of microplastic contamination in surface waters of Loktak Lake, a Ramsar site in the Eastern Himalayas

Scientific Reports 2026
Pallabi Borah, Naphibaniarlin Kshiar, Arun Jyoti Nath, Sneha Dutta Chowdhury, Demsai Reang

Summary

Scientists found tiny plastic particles (microplastics) in the water of Loktak Lake, a unique floating lake in India, with the most pollution near crowded areas like floating homes, markets, and fishing zones. Most of these plastic bits were very small, meaning they could easily be swallowed by fish or people, and some were made of PVC, a plastic type linked to cancer risk. While current health risk levels appear low based on today's exposure, this study is an early warning sign that plastic pollution is creeping into even remote, protected wetlands—something worth watching closely.

Study Type Environmental

Microplastic (MP) pollution in freshwater ecosystems is an emerging environmental threat yet remains poorly documented in ecologically sensitive wetlands. Here, we present the first integrated assessment of MP occurrence, distribution, polymer composition, and associated risks in the surface waters of Loktak Lake (Manipur, India), a globally unique floating lake system and Ramsar site. Surface-water samples were collected during the pre-monsoon season (March 2024) from the 0-20 cm surface layer from 13 geospatially distributed sites. MP abundance exhibited pronounced spatial heterogeneity, ranging from 8 to 82 particles L⁻¹ (mean 47 ± 23.8 particles L⁻¹). MP hotspots are concentrated near densely inhabited islands, floating hutments, market-associated zones, and active fishing areas. Spatial concentration variation was statistically supported through a strong monotonic association between MP abundance and the anthropogenic intensity. Size profiling showed a dominance of small particles, with particles < 2000 μm accounting for 91.38% of total MPs, highlighting high bioavailability potential. Predominant MP morphotypes included fibers and fragments. Polymer identification confirmed the presence of common consumer and activity linked polymers, including polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA), and polyvinyl chloride (PVC). EDX analysis revealed associated trace metals including Pb, Ru, and Pt, indicating potential polymer-metal interactions. An environmental risk evaluation integrating indices indicated elevated ecological concern in high-activity zones. The estimated human health risks (non-carcinogenic and carcinogenic) via ingestion remained within acceptable thresholds under current exposure assumptions. However, the presence of carcinogenic polymers such as PVC raises significant concern. This study provides a critical baseline to guide monitoring, wetland management, and targeted source-control interventions in Ramsar and high-value freshwater ecosystems.

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