Microplastic contamination in environmental matrices of multi-basin Dal Lake, Kashmir

Microplastic (MP) pollution threatens freshwater ecosystems due to its persistence and ecological risks. This study investigates MPs across environmental matrices of water, sediment, and fish (Cyprinus carpio var. communis and C. carpio var. specularis) in multi-basin Dal Lake through fluorescence microscopy and Raman spectroscopy to assess MP abundance, morphology, and polymer composition. Sediments contained substantially higher MP concentrations (385-9178 MPs/kgDW) than water (10-157 MPs/L) and fish (0-15 MPs/individual), with Gagribal basin identified as contamination hotspot. MPs were dominated by pellets and fragments in both water (74.74 % and 19.25 %) and sediment (68.05 % and 21.83 %), while fish showed different trend with pellets (46 %), fibers (34 %), and fragments (15 %) reflecting bioavailability and feeding behavior. Polymer analysis revealed water contained mainly polyethylene (PE, 54.38 %), polypropylene (PP, 24.56 %), and polystyrene (PS, 21.05 %), while sediments accumulated primarily PS (37.69 %) and Polyethylene terephthalate (PET, 25.65 %) and fish showed preferential accumulation of PE (39.7 %) and PET (33.82 %). A strong correlation between MP retention and clay and silt was observed, indicating that finer particles trap more MPs, making deposition grain size-driven rather than depth-dependent. Ecological risk assessments using pollution load index (PLI), polymer hazard index (PHI) and potential ecological risk assessment (PERI) indicated moderate pollution loads but notable polymer-specific hazards. Fish ingestion revealed that MP ingestion patterns closely mirrored basin-wise polymer composition, with smaller particles (<100 μm) being more bioavailable, raising concerns over trophic transfer and bioaccumulation. Basin-specific differences in MP abundance and polymer composition reflect both hydrodynamic processes (inflows and flushing) and localized anthropogenic pressures from sewage treatment plants, houseboats, and tourism. These combined drivers shape the spatial variability of MPs in Dal Lake and highlight the need for targeted policy interventions to curb MP pollution, given the potential risks to aquatic life and human health through contaminated water and fish consumption.