Microplastic pollution in urban Lake Phewa, Nepal: the first report on abundance and composition in surface water of lake in different seasons.

Microplastics are man-made pollutants which have been detected in surface water and groundwater. Research on microplastic concentration in aquatic environment is attracting scientists from developing countries, but in Nepal no information regarding microplastic in freshwater system is available. Therefore, this study investigates the presence and abundance of microplastic in lake surface water of Phewa Lake, the second largest lake in Nepal. The average concentration of microplastic for surface water was 2.96 ± 1.83 particles/L in winter (dry) season and 1.51 ± 0.62 particles/L in rainy (wet) season. Significant difference with t = 4.687 (p < 0.01) in microplastic concentration was observed in two different seasons. Fibers (93.04% for winter and 96.69% for rainy season) were the commonly found microplastic type in lake water and transparent as the dominant color for the two seasons. Almost all the detected microplastic were found to be < 1 mm in size. Due to the small size of microplastic and unavailability of micro-Fourier transform infrared spectroscopy (μ-FTIR) and Raman spectroscopy in Nepal, polymer identification was not done. The findings from this study can provide a valuable baseline data on microplastics for the first time in Nepal's freshwater lake environment.