Microplastic Pollution in Urban-Dal Lake, India: Uncovering Sources and Polymer Analysis for Effective Assessment

The prevalence of microplastic contamination has become a major problem worldwide, with the potential to harm aquatic ecosystems and human well-being. This study investigated the occurrence of microplastics (MPs) in sediment samples obtained from Dal Lake, situated in the northwest Himalayas, India. Thirty-two sediment samples collected from different sites inside the lake were thoroughly analyzed using a stereomicroscope. The research showed that the average concentration of microplastics (MPs) in the sediment was 416 ± 38 MP/kg (mean ± standard error, n = 32) based on the weight of the dry sediment. The most frequently seen colours of MPs were blue, white, black, red, and orange. The majority of the total consists of fiber-shaped particles, accounting for 86.5%, while fragments make up 11%, and films make up 2.5%. Raman spectroscopy revealed the high occurrence of Polyamides, namely Nylon, comprising 62.5% of the sample. Small amounts of Polyethylene, Polyvinylchloride, and Polypropylene were also detected. The findings of this research suggest that tourism, fishing activities, and untreated wastewater are major contributors to the presence of microplastics (MPs) in the lake. In addition, local community habits, such as the use of packaging materials, automobiles, and cosmetics, also contribute to microplastic pollution. Sediment quality was assessed using hazard indicators such as the Polymer Hazard Index (PHI), Pollution Load Index (PLI), and Potential Ecological Risk Index (PERI). The occurrence of high levels of PHI (> 1000) in some regions is attributed to the presence of high-risk polymers such as polyamide (PA) and polyvinyl chloride (PVC). The sediments were classified as medium-risk according to the PERI values, whereas the PLI values revealed a relatively low contamination level (< 10), falling into Hazard Category I. The results of this research provide a crucial understanding of the categories, dispersion, and sources of microplastics (MPs) in Dal Lake. This understanding serves as the basis for focused efforts to protect the lake's biological balance and ensure the well-being of humans, both now and in the future. Graphical abstract: [Figure not available: see fulltext.]