Abstract
Rivers act as temporary sinks of microplastics and a key medium allowing microplastics to enter the ocean. In this study, microplastics pollution in river shore sediment of the Indian Himalaya, including the Brahmaputra River and the Indus River was discussed. Sampling campaigns were performed in years 2018 and 2019. Sample pretreatment was performed using Na2WO4·2H2O for density separation and H2O2 for oxidation of organic material. Microplastics analysis was performed by using FTIR microscope. The smaller size of microplastics 20–150 μm were more abundant (531–3485 MP/kg in the Brahmaputra River and 525–1752 MP/kg in the Indus River) than microplastics in size range between 150 μm and 5 mm (20–240 MP/kg in the Brahmaputra River and 60–340 MP/kg in the Indus River). Microplastics were found in sediments of all sampling sites. Fragmented, secondary microplastics were dominant in the river shore sediment of the Indian Himalaya. This study contributes towards filling research gap of microplastics in India's freshwater source and highlights the importance of in-depth complete studies of microplastics in the rivers that act as pathways and sinks for microplastics.
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•Microplastics in shore sediment of Brahmaputra River and Indus River were studied.•Fragmented, 20 ̶150 μm size microplastics dominated the samples.•Polypropylene and polyethylene were most abundantly found.•Anthropogenic activities and hydrological factors impacted microplastics distribution.•Surface morphology of microplastics showed mechanical and oxidative weathering.