Microplastic pollution in Kolavai Lake, Tamil Nadu, India: quantification of plankton-sized microplastics in the surface water of lake

The prevalence of microplastics (MP) (< 5 mm) in aquatic habitats has recently raised concerns owing to their influence on humans and aquatic organisms, as they absorb organic pollutants and pathogens from the surrounding media because of their higher surface-to-volume ratio. Freshwater systems are severely affected by the increased intake of discarded waste from diverse sources. This study focused on the microplastic-to-zooplankton ratio and its potential impact on the environment's food chain. The sampling sites of Kolavai Lake were divided into three zones (18 stations) to investigate the spatial distribution of microplastics and zooplankton biota. The average microplastic abundance was 6.1 ± 2.5 particles/L. Fourier transform infrared spectroscopy (FTIR) and SEM analysis were performed to understand the chemical composition and surface morphology of microplastics. Water samples collected along the Central and Southern Zones revealed a high abundance of microplastics, which might be due to anthropogenic activities. A negative correlation was observed between the abundance of microplastics and zooplankton. The microplastic-to-zooplankton ratio was found to range from 0.05 to 0.74. Furthermore, the impact of microplastics in the lake ecosystem was analysed using the size and shape descriptors for both zooplankton and microplastics. These findings suggest that microplastics built up in aquatic environments, particularly those with rich biota, could be a severe concern because of their capacity to infiltrate the food web.