Occurrence and Distribution of Microplastics from Nepal’s Second Largest Lake

Abstract

Due to its harmful impact on biota, microplastic pollution is the top priority research in many countries. However, there is hardly any research on microplastic pollution in Nepal’s freshwater. Therefore, the present research was accomplished in Phewa Lake to evaluate the occurrence and distribution of microplastic contamination in shoreline sediments. The average abundance of microplastic varied from 55 to 122.5 items/kg dry weight (dw). The highest value appeared on densely populated eastern side of the lake and the western region reported the lowest concentration of microplastic. With regard to the shape, fibers dominated the sediments of Phewa Lake accounting for 62.03%. The dominant color was transparent (23.53%) followed by blue (21.39%). The size category 0.2–1 mm recorded the highest abundance of microplastic. Similarly, Fourier transform infrared spectroscopy (FTIR) reveal the dominant polymer type as polypropylene (PP) and polyethylene (PE). The outcome of this result adds a step toward filling the existing knowledge gap and providing a database on microplastic pollution in Nepal’s freshwater.

Microplastics research in Nepal: Present scenario and current gaps in knowledge

“… Filters were kept in a petri dish after use. Air blanks were kept to check for possible contamination [ 25 ] Collected 5 L surface water (0–20 cm) using a steel bucket, sieved through a 75-μm brass filter on-site, transferred to a glass bottle, and stored at 4 °C for analysis. Treated water sample with 20 mL 30 % H 2 O 2 and 20 mL Fe solution.…”

“… S no components Color Shape Size Abundance Type of polymers References 1 Lakeshore sediments (Phewa Lake) Transparent followed by red Fibers (78.11 %) 0.2–1 mm size (70.65 %) 100.5 ± 58.6 items/kg dry weight Polypropylene (PP) (42.86 %) followed by polyethylene (PE) [ 46 ] 2 Shoreline sediments (Phewa Lake) transparent (23.53 %) blue (21.39 %). Fibers 62.03 % 0.2–1 mm (highest) Range in between 55 and 122.5 items/kg dry weight Polypropylene (PP) and polyethylene (PE) [ 25 ] 3 Lake water (Phewa Lake) transparent (both seasons) Fibers 96.7 % (wet season) (93.04 % winter) <1 mm in size 2.96 ± 1.83 MP/L in winter and 1.51 ± 0.62 MP/L in wet season – [ 24 ] 4 Water and sediments (Koshi River) Blue and black Fibers (98 %) small MPs (<1 mm) accounted for approximately 60 % of all MPs. Mean abundances of microplastics in water and sediment were 202 ± 100 items/m3 and 58 ± 27 items/kg, dry weight, respectively Polyethylene (PE), polyethylene terephthalate (PET), polyamide, polystyrene (PS) and polypropylene (PP) [ 27 ] 5 Snow/Stream water (8440 m.a.s.l) - Fiber <5 mm 30 MP/L (snow) 1 MPs/L (stream water) Polyester [ ...…”

“…The abundance of microplastics is recorded in snow and stream water of Mount Everest [ 20 ]. Microplastics have been detected in air [ 21 , 22 ], soil [ 23 ], lake water [ 24 ], lake sediments [ 25 ], beach sediments [ 26 ], river water [ 27 ], Ships ballast water and seawater [ 28 ], table salt [ 21 ], drinking water [ 29 ], glaciers [ 30 ], human stool [ 31 ], sewage sludge [ 32 ], fishes [ [33] , [34] , [35] , [36] ], food items [ 37 ] and many living creatures. Microplastic pollution is distributed across the atmosphere, hydrosphere and pedosphere [ 38 ].…”

Bioplastics against Microplastics: Screening of Environmental Bacteria for Bioplastics Production

“…Plastics (polymeric materials) are highly functional materials that have become an essential part of the products we use in our daily life due to their ease of production and robustness. Around 360 million tons of plastics have been produced in 2020 around the world [1]. As more plastics are used, especially with their short-use life span, more waste surfaces.…”

“…As it was emphasized in Ref. [1], the worldwide use of disposable face masks during the pandemic time and still now is an additional source of microplastics in the environment. Plastics are majorly manufactured from petrochemical feedstock, accounting for 80% of the total produced plastics.…”