Microplastic contamination and risk assessment in the biotic and abiotic components of freshwater Manasbal Lake, western Himalaya, India

Abstract Microplastics (MPs) have emerged as ubiquitous and persistent pollutants that impact all compartments of urban and mountain environments. However, studies combining abiotic and biotic components to assess MPs abundance and characterisation from remote mountain catchments of the Himalaya are still limited. This study examined abundance, types, and ecological risks of MPs in abiotic (surface water, water column, snow) and biotic (fish) components of Manasbal Lake, an ecological hotspot in the Kashmir Valley, western Himalaya. MPs were extracted using density separation and subsequently examined microscopically to determine their abundance, shape, color, and size. The concentration ranges were observed at 59–188 MPs/L in surface water, 8–15 MPs/L in water column, 11–18 MPs/L in snow, and 7–13 MPs/individual in fish samples. The MPs shape, color and polymer composition of biotic and abiotic components were dominated by fibers, transparent color and polyethylene terephthalate (PET) type, respectively. Most of the MPs observed were in the size range of 0.1–1 mm, with significant contributions from local pollution sources. We observed higher abundances of MPs away from stream inlets or residential areas, suggesting complex hydrodynamics and wind-driven surface transport in the lake. Risk assessment indices reveal that fibers exhibit the highest risk levels, posing a significant risk to the lake ecosystem. Further, a comparative analysis with other regional western Himalayan Lakes highlights the dominance of fiber MPs, emphasizing the need for multidisciplinary research efforts to address the growing concern for MPs contamination. This study underlines the necessity for integrated catchment-scale land-use planning while advancing our understanding of MPs pollution dynamics in lake ecosystems of the western Himalaya.