Metal nanoparticles in glaciers: occurrence, transport, and implications for freshwater ecosystems

Abstract

Glaciers are critical freshwater reservoirs, yet their vulnerability to emerging contaminants remains poorly understood. Here, we investigated metal nanoparticles (MNPs) in snowpacks and runoffs from five glaciers of the southern Qinghai-Tibetan Plateau, revealing widespread presence, with Ti NPs and Al NPs predominating (up to 6983 and 111.5 ng L⁻¹, respectively). Single-particle analysis shows downstream accumulation and size enlargement of MNPs in glacial runoffs, significantly correlated with hydrodynamic conditions, underscoring the role of runoff dynamics in shaping MNP transport and retention. Laboratory experiments indicate that environmentally relevant concentrations of individual or combined MNPs did not significantly inhibit Chlorella sp. growth, whereas exposure to Ti NPs at around 15-fold the maximum detected concentration causes marked growth inhibition, suggesting current levels may be approaching a potential ecological risk threshold. Our study provides comprehensive insight into the occurrence, fate, and ecological risk of human-derived MNPs in remote glacier environments, highlighting the importance of global strategies to safeguard high-altitude freshwater resources and ecosystem health from emerging contaminants.