Microplastic contamination in high-altitude glacier lakes in Northern Anatolia

Microplastic (MP) pollution remains a growing global concern for aquatic ecosystems, including remote environments. In this study, we investigated the presence, distribution, and composition of MPs in surface water and sediment of eight high-altitude glacier lakes located in the Kaçkar and Keşiş Mountains, the northeastern part of Türkiye. For surface water samples, MP abundance ranged from 0.2 to 1.6 MP/L, with the highest concentration observed at Aygır Lake (S2). For sediment samples, MP abundance ranged from 13 to 121 MP/kg, with the highest concentration observed at Balık Lake (S1). Statistical analysis indicated significant spatial variations in microplastic abundance across the lakes. Five different polymer types were identified: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyamide (PA), and polystyrene (PS). Fibers were the dominant shape in water samples, comprising up to 70%, and fragments were the most common shape observed in sediment samples. Although the Pollution Load Index (PLI) indicated a low level of microplastic contamination across the sampling stations, the Polymer Risk Index (PRI) revealed a high to dangerous level of ecological risk due to the presence of hazardous polymer types. Our findings indicate that contamination caused by local human activities, such as summer tourism, camping, animal husbandry in nearby grasslands, and mountaineering, serves as a significant source of MPs in the study area. To reduce MP pollution in high-altitude glacier lakes, it is essential to implement long-term monitoring programs that track not only human activities but also airborne contamination and deficiencies in waste management.