Microplastic Contamination in Ulhas River Flowing Through India's Most Populous Metropolitan Area

In addition to providing drinking water and a means of transportation, urban rivers also support inland fisheries, agriculture, and industry. Urban rivers, however, are continually being influenced by anthropogenic stressors, such as plastic pollution, and are thus predicted to play a significant role in the worldwide ocean plastic pollution problem. The management of urban rivers remains one of the major challenges due to the lack of knowledge on the degree of riverine microplastics (MPs), particularly in nations like India. Therefore, the current study investigates on MP pollution in the Ulhas River, which runs through Mumbai, India's most populous metropolis, and contributes significantly to MPs entering the Arabian Sea. MPs were extracted from sediment samples collected across the Ulhas River basin and then identified using FTIR-ATR, Raman spectroscopy, and SEM-EDX. MP particles were detected in every sediment sample taken from the Ulhas River, and their concentration ranged from 40 to 600 particles kg(-1) of sediment. LDPE, HDPE, polypropylene, polystyrene, polyethylene, polyester, and nylon were found to be the primary polymers. When combined with demographic estimates and land use patterns, the estimated pollution load index (PLI), polymeric risk (H), and pollution risk index (PRI) show that five of the nine sub-basins are expected to represent significant ecological risk and are therefore referred to as hotspots of MP pollution. The majority of MPs in the Ulhas River originate from secondary sources. Examining MPs using SEM-EDX indicates their ageing, disintegration, and association with biofilm. The information obtained from this study's data is useful for establishing water quality standards, monitoring and controlling pollution efficiently, and serving as a foundation for further research.

Automated summary

In addition to serving as a source of drinking water and transportation, urban rivers provide support for inland fisheries, agriculture, and industry. However, these rivers are heavily impacted by human activities, including plastic pollution, and are predicted to contribute significantly to the global ocean plastic pollution problem. The management of urban rivers remains a major challenge due to limited knowledge on the extent of riverine microplastics, especially in countries like India.