Microplastics at the ‘roof of the Americas’: widespread presence in snow on Mount Aconcagua, Central Andes, Argentina

Microplastics (MPs) pollution has emerged as a pervasive contaminant in remote environments; however, its occurrence in high-altitude snow remains poorly constrained. Here, we provide baseline evidence of MP contamination in snow from four mountaineering camps on Mount Aconcagua (6,962 masl), the highest peak in the Americas and in the entire Western and Southern Hemispheres. Microplastics were identified using µFTIR-ATR spectroscopy. The mean MPs concentration was 38 MP L -1 , with site-specific values of 79 ± 37, 27 ± 8.3, 40 ± 16, and 5 ± 1 MP L -1 at the Plaza de Mulas base camp, and at the Canada, Nido de Condores, and Berlin higher elevations camps, respectively. Significantly higher concentrations at the base camp highlight the influence of intense human activity on MP accumulation, even in these remote high-mountain settings. Fibers (<5 mm), predominantly blue, were the dominant shape (90%), and polymer analysis revealed polyester, polyethylene, and epoxy as the main constituents. These findings indicate that snow is an effective matrix for assessing atmospheric deposition of MPs in andine environments. The spatial distribution of MPs suggests that local emissions associated with mountaineering activities represent a key source, although long-range atmospheric transport cannot be excluded. Our study provides the first documented evidence of the pollution of MPs in this world-famous climbing area, underscoring the vulnerability of high-altitude ecosystems to plastic pollution. Given the ecological significance and increasing human pressure in the Aconcagua Provincial Park, these results highlight the urgent need for targeted waste management strategies and regulatory actions to mitigate MP inputs in this fragile mountain environment.