Microplastics Contamination in Water and Sediments: Seasonal and Spatial Distributions from the Urban Wetlands of Coimbatore, Tamilnadu, India

Plastics are becoming widespread and universal contaminants after they are reduced in size (< 5 mm) to form microplastics (MPs). MPs contamination in freshwater ecosystems poses a severe threat to biota. The present study investigated the seasonal and spatial distributions of MPs in significant urban wetlands such as Ukkadam (UD), Selvampathy (SP) and Singanallur (SN) in Coimbatore, Tamilnadu, India. The results indicated that MPs ranged from 10 to 33 particles/L, 6 to 34 particles/L, and 9 to 30 particles/L in the surface water of UD, SP, and SN, respectively. Moreover, the UD, SP, and SN shoreline sediments contained 17 to 45 particles/0.5 kg, 14 to 47 particles/0.5 kg, and 15 to 45 particles/0.5 kg, respectively. The MPs length ranges were between 0.17 and 1.6 mm and 0.16 and 1.1 mm in surface waters and shoreline sediments, respectively. The colour distribution of the MPs in the examined environmental matrices was dominated by blue, transparent, and black, whereas fibres and fragments were the most common shapes of the MPs. The dominant polymers of the MPs were polyethylene terephthalate and polypropylene from the environmental matrices of the studied wetlands. Among the seasons, the monsoon season influences the abundance of MPs in both water and sediments of the UD, SP, and SN wetlands. Spatial influences from each lake reveal the transfer of MPs from urban environments. The present findings reveal the seasonal and spatial influences on the abundance, shape, colour and polymer nature of MPs in Coimbatore’s wetlands, reflecting the risk of MPs pollution.