Microplastic surge in the Ariyankuppam river, Puducherry, India: A study on abundance, characterization, and pollution load index

The increasing rate of microplastic (MP) pollution in the aquatic environment poses an escalating threat to marine ecosystems and several health concerns to humans. Ocean and Sea MP pollution has been a grave concern in recent decades, and rivers are considered one of the main channels that carry MP to the sea. Here, we investigated the MP abundance in the Ariyankuppam River, which flows through the Puducherry region in South India and merges with the Bay of Bengal. The water and sediment samples were collected from ten locations along the river over three months, from January to March 2024, coinciding with the post-monsoon phase in Puducherry, to understand the impact of seasonal variations on MP abundance. The average MP abundance of sediments and water was found to be 136.33 +/- 24.75 particles/Kg and 124.83 +/- 22.44 particles/L, respectively. A total of 7837 MP particles were detected, with approximately 52.2 % and 47.8 % originating from sediment and water samples. Fibers were major polymer forms, with an abundance of 79.4 % in sediment and 87.9 % in water samples. The classification of MP (0-3000 mu m) reveals predominance of smaller particles, mainly within 0-500 mu m and 500-1000 mu m. High-density polyethylene (HDPE) and Low-Density Polyethylene (LDPE) were the dominant polymer types in sediments and water samples collected from ten sites along the river. Our results found not much of a significant difference in MP abundances across the months in both sediment and water samples. The Pollution Load Index (PLI) assessment indicated a Hazard Level I (<10), a minimal risk level. These data will help the local government and other agencies take necessary measures for mitigation strategies to safeguard these vital water bodies.