Linking microplastic pollution and nutrient dynamics in the sediments of the Gokyo Lake Cluster, a high-altitude Ramsar site of Nepal

High-altitude freshwater ecosystems are increasingly at risk from emerging pollutants like microplastics, yet evidence from the Himalaya remains limited. This study evaluates microplastic contamination and nutrient dynamics in the sediments of Gokyo Lake Cluster, a Ramsar site in the Everest region of Nepal. Sediment samples were collected from 10 sites across three lakes and analyzed for microplastic abundance, shape, colors, size, and pollution indices. Concurrently, physicochemical parameters (pH, conductivity, nitrogen, phosphorus, potassium, and organic matter) of sediments were also measured to investigate potential environmental drivers. Of the three lakes (Longpanga Tsho, Taujung Tsho, and Gokyo Tsho) studied, the third lake (Gokyo Tsho) showed the highest microplastic abundance predominantly composed of fibers and fragments with Contamination Factor and Microplastic Pollution Load Index values suggesting low to moderate contamination and minor risk. Correlation analysis revealed a strong negative association between microplastics and pH and a positive association with organic matter. However, non-metric multidimensional scaling ordination did not identify any environmental variable as a significant driver of spatial variation in microplastic composition. These findings highlight the vulnerability of these wetlands to microplastic pollution and suggest routine monitoring and targeted pollution control strategies to safeguard the ecological integrity of the Himalayan wetlands.