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Environmental Sources
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Monthly variation and transport of microplastics from the Soan River into the Indus River
The Science of The Total Environment2023
12 citations
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Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Score: 40
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0–100 AI score estimating relevance to the microplastics field. Papers below 30 are filtered from public browse.
The first year-long monthly study of the Soan River (Pakistan) found microplastics present in high concentrations throughout the year — peaking in August at over 641 items/m² during the monsoon — with PET fibers as the dominant form. Seasonal flow dynamics and riverbed morphology shaped the distribution patterns, and the urban character of the catchment drove contamination. As a tributary of the Indus, the Soan represents an important pathway for microplastics reaching one of Asia's major river systems and ultimately the ocean.
The presence of plastic and microplastic pollution in freshwater systems receives extensive concerns for its accumulative trend and potential ecological impacts. This is the first annual study that investigated the monthly profile of plastic pollution in the mouth of the Soan River. Plastic pollutants comprising microplastic content up to 91.7 % were abundantly found during different seasons around the year, ranging from 132.7 items/m to 641.3 items/m. The average abundance of plastics was significantly higher in August (641.3 ± 23.7 items/m) than in other months. Overall, fibers, large microplastics (L-MPs), and transparent items were dominant by shape (57.7 %), size (61.9 %), and color (24.6 %), respectively. The highest average number of fibers (374.3/m) and L-MPs (396 items/m) were recorded during May and remained higher in the surface water from December to May. Fragments (432.3/m) and S-MPs were observed higher (362.3 items/m) during the peak rainy month of the summer monsoon season (August). Variations in the abundance and morphotypes were seemingly not only influenced by the seasonal change but also might be due to hydromorphological characteristics of the river, especially riverbed morphology, and the flow of the water. Only 5.2 % of the total items found were identified using μ-FTIR (micro-Fourier Transformed Infrared Spectroscope) which consisted of 70.7 % plastic items. Spectroscopy revealed that polyethylene terephthalate was an abundantly found polymer that largely prevailed in the form of fibers, followed by polypropylene and polyethylene. Most of the fragments, foams, and films were composed of polypropylene, polystyrene, and rayon respectively. Being an urban river, the polymeric profile demonstrated that anthropogenic activities had a significant impact on polluting the river. These findings are a very important source to understand the profile of plastic pollution in the Soan River and also a significant reference for policy-making in controlling plastic pollution among the riverine networks.