Microplastics in water, sediments, and fish at Alpine River, originating from the Hindu Kush Mountain, Pakistan: implications for conservation

Microplastics (MP) pollution is an emerging threat to life and the environment. These particles are not restricted to human-inhabited lands but also found in different mountains and glaciers where the human population is relatively low. These MPs make their way to the river ecosystem from glaciers, rains, and municipal and industrial effluents. The current study was designed to highlight MPs' pollution in water, sediments, and fishes of the Swat River: originating from the Hindu Kush Mountain Range. These samples were collected from eight different sites across the river. An average concentration of MPs detected in water samples (305.79 ± 289.66 MPs/m³), fish (12.54 ± 8.02 MPs/individual), and sediments (588.29 ± 253.95 MPs/kg). The highest concentration was observed among water samples at Mingora city and the lowest at the confluence point of the rivers near Charsadda being 753.71 ± 330.08 MPs/m³ and 57.64 ± 31.98 MPs/m³, respectively. MP concentrations in the sediment samples were also the highest at Mingora city (834.0 ± 367.21 MPs/kg), and lowest at Chakdara (215.0 ± 20.0 MPs/kg). Among the fish samples, Schizothorax plagiostomus contained the highest while Wallago attu contained the lowest MP concentrations corresponding to 17.08 ± 8.27 MPs/individual and 5.0 ± 2.36 MPs/individual, respectively. Fibers were the most prevalent MPs in all the matrices representing 80%, 92%, and 85% of the total MP count in water, sediments, and fish samples. These findings highlighted that freshwater ecosystem are not free from MPs and are as much vulnerable to anthropogenic activities as marine ecosystem. Therefore, need attention not less than marine ecosystem awareness, education, ecotourism, sustainable reduction in plastic use, and strict rules and regulations could be helpful to prevent the anthropogenic menace.