Unveiling microplastic menace: analyzing abundance, distribution, and sources across diverse land use types in South India

The investigation of microplastics (MPs) from the basin level is essential to understanding the fate and transport of MPs and for future modeling studies. This study explored the MPs in the Upper Ponnaiyar Basin, situated in Tamil Nadu, India, and examined their characteristics and sources in the terrestrial environment. The extraction of samples was performed using wet peroxide oxidation and subsequent density separation. The physical and chemical characteristics of extracted samples were analyzed using a stereomicroscope and Raman spectroscopy. The total concentration of MPs was found to be 1941.75 particles/kg, varying from 6.75 to 274.5 particles/kg. Urban regions contributed significantly higher concentrations of MPs compared to agricultural regions. The population showed a positive correlation to MPs concentration in agricultural regions. However, in rural and urban areas, the correlation was negative and non-existent, respectively. This observation indicated that the improperly disposed wastes in the urban and rural areas were disintegrated due to the heat and photo-induced fragmentation, highlighting the need to develop waste disposal systems in these regions. The results suggested an evident disparity in the distribution of MPs between the cultivated (24.75 +/- 10.45 particles/kg) and uncultivated (18 +/- 12.26 particles/kg) agricultural fields, which can be attributed to fertiliser, manure and ploughing. The findings of this study can serve as a reference for future studies.