Snow as an indicator of atmospheric transport of anthropogenic particles (microplastics and microfibers) from urban to Arctic regions

We report anthropogenic particles (APs) > 100 mu m, including microplastics and microfibers, from 70 surface snow samples collected from the urban Greater Toronto Area, remote and sparsely inhabited regions in the Yukon and Northwest Territories, and the unpopulated high Arctic. Concentrations and proportions of particles of anthropogenic origin were conservatively estimated after blank and "anthropogenic origin" corrections were performed based on visual analysis and micro-Fourier transform infrared spectroscopy ( mu FTIR). APs were dominated by microfibers (95%-100%), with variable concentrations across and within regions. Microfibers were distinguished as synthetic, regenerated semi-synthetic, anthropogenically modified cellulosic, and natural cellulosic or proteinaceous. Among microfibers with confirmed anthropogenic origin, most were polyester/PET (8%-22%) and semi-synthetic rayon (1%-18%), with anthropogenic cellulose comprising a small proportion (3%-7%) across all regional areas. Greater diversity of coloured nonfibrous particles (fragments, films, and foams) in settled regions (i.e., Greater Toronto Area (GTA) and Carcross, Yukon) suggests direct input from local sources. Back trajectory analyses performed for days leading up to sample collection showed high-frequency transport ( > 10%) from population centres exceeding 200 km distance. Our findings of APs in snow from uninhabited areas support the hypothesis that APs, especially microfibers, undergo long-range atmospheric transport whereby snow can scavenge and deposit APs in remote northern regions.