Transportation of microplastics from the rural area into the urban area of the Kosasthalaiyar River in the metropolitan city of Chennai

Abstract

Microplastics are smaller plastic polymers (less than 5 mm) distributed in different habitats from terrestrial to aquatic environments worldwide. In freshwater bodies the microplastic accumulates in various sources includes surface runoff, wastewater treatment plant effluents, tourism, improper disposal of wastes, wind actions and anthropogenic activities. The Kosasthalaiyar River is one of the three major rivers in the metropolitan city Chennai, which runs through a large industrial area. It has the large catchment area of 3625 km2. In this study, the surface water samples (Sample Stations, n = 31) were collected in the month of October, 2022 are analysed for microplastic contamination. The highest microplastic accumulation was found in the Tamaraipakkam Dam. The microplastics were classified according to the size, colour and shape. The fibre particles were dominant (78%), followed by film (12%), fragment (7%) and foam (3%). Transparent microplastics were found to be predominant with 42% abundance. The microplastic particles greater than 0.5 mm were isolated and examined under the FTIR spectroscopy and Scanning Electron Microscopy (SEM). High Density Polyethylene dominated to about 44%, followed by Polypropylene (28%). The SEM image illustrated significant morphological alterations of the Microplastics particles. Seasonal sampling is essential to assess further for the contamination range in the Kosasthalaiyar river.