Microplastics in the high-altitude Himalayas: Assessment of microplastic contamination in freshwater lake sediments, Northwest Himalaya (India)

In this study, we assess the magnitude, type, and sources of microplastic (MP) in lake bottom sediments collected from freshwater Anchar Lake, located in the Kashmir Valley, Northwest Himalaya. The MP identification was done on twenty-four lake bottom sediment samples under a stereo-microscope, and their polymer compositions were characterized using an Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. The study reveals that 606 +/- 360 (average +/- SD, n = 24) numbers of MP were present per kilogram of dry sediment samples, with fibers (91%), fragments/films (8%), and pellets (1%) dominating the shape groups. Polyamide (PA, 96%) was the dominant polymer composition present in the sediment samples, followed by polyethylene terephthalate (PET, 1.4%), polystyrene (PS, 1.4%), polyvinyl chloride (PVC, 0.9%), and polypropylene (PP, 0.7%). Polymer Hazard Index (PHI) and Pollution Load Index (PLI) were used to evaluate the quality of sediments. It was noted that high PHI values (>1000) were due to the presence of PVC polymer. According to PLI values, sediments in the Anchar lake are less contaminated with MP. We conclude that MP in the Anchar Lake have a complex source derived mostly from the automobile, textile, and packaging industries.

Automated summary

This study assesses the quantity, type, and sources of microplastics in lake bottom sediments from Anchar Lake in the Northwest Himalaya. The analysis reveals that the sediments are significantly contaminated with microplastics, with the dominant polymer composition being polyamide. The presence of PVC polymers results in a high Polymer Hazard Index. However, according to the Pollution Load Index, the sediments in Anchar Lake are relatively less contaminated. The microplastics in the lake predominantly originate from the automobile, textile, and packaging industries.