Investigation of microplastic pollution in Torghabeh River sediments, northeast of Iran.

Rivers are the route of transfer of microplastics from upstream to downstream areas and seas. Microplastic tracing in river sediments can provide a better reflection of long-term microplastic pollution. This study aimed to investigate the occurrence and distribution of microplastic contamination in the Torghabeh River sediments in Khorasan Razavi (Iran). Sediment samples were collected from four sites along the river. Microplastic particles were classified according to type, shape, and color. The average microplastic concentration was 8 ± 2.82 particles per 100 g of dry sediments. Most of the microplastics detected in river sediments were in the form of filaments and fragments. A total of 32 polymers were identified and isolated from sediments. According to Raman spectroscopy results, polystyrene had the highest abundance compared to polyester, polyethylene, and other polymers. The predominant shape of the microplastics in the river sediment was filament and fragmented. It can be concluded that the areas that were exposed to human activity contained more microplastic contamination. The present investigation can also provide baseline information for the study of riverine ecosystems.