Spatiotemporal dynamics of microplastics burden in River Ravi, Pakistan

Microplastics (MPs) are emerging pollutants with detrimental effects on aquatic organisms and human health. The massive generation of plastic waste on land leads to MPs pollution in the aquatic environment. Some reports highlight the abundance of MPs in Pakistan however, no detailed research has been documented about the presence of MPs in the riverine environment. In this regard, the present study highlights the spatial distribution of MPs in River Ravi during monsoon and post-monsoon seasons. The MPs in water and sediment samples were isolated through wet peroxide oxidation digestion, density separation, and filtration followed by microscopic quantification and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The results showed that in water samples, the average concentrations of MPs in monsoon and post-monsoon seasons were 768 ± 869 MPs/m3 and 1324 ± 1925 MPs/m3, whereas, sediments depicted 5323 ± 3792 MPs/kg-dry weight and 2637 ± 2701 MPs/kg-dry weight, respectively. Similarly, fiber was the most abundant type of MPs, and Polypropylene (PP), Polyethylene (PE), Polyester (PES), and Polystyrene (PS) were the most dominant polymer types in both environmental matrices. In terms of their sources, urban sprawl, industrialization, improper solid waste management, and overuse of plastic products are positively correlated with MPs level in River Ravi. Moreover, this is the first study on the spatiotemporal distribution of MPs in River Ravi from Pakistan and indicates the high burden of MPs pollution. Consequently, it will provide scientific information to policymakers and river managers to deal effectively with plastic pollution.