Microplastics in glaciers of Tibetan Plateau: Characteristics and potential sources

Microplastics (MPs) in glaciers of remote areas are a hot topic linking the global transport of atmospheric MPs. The Tibetan Plateau (TP) holds large volume of glaciers, providing an effective way to trace MPs transport. Moreover, MPs in glaciers may have adverse effects on the local ecosystem and human health. In this study, we investigate MPs in snowpits collected from six glaciers across the different domain of the TP. The average abundance of MPs in six snowpits is 339.22 ± 51.85 items L^-1 (with size ≥10 μm) measured by Agilent 8700 Laser Direct Infrared Chemical Imaging System (LDIR), represented by relatively high MPs abundance in the southern TP and low in the northern TP. The polymers with lower density, namely polyethylene (PE), polyamide (PA), and rubber, are the main MPs types, which are predominated by fragments with sizes smaller than 100 μm in each snowpit. Sources of MPs on glaciers include local tourism and vehicle traffic emissions of MPs. Meanwhile, long-range atmospheric transport of MPs from surrounded regions cannot be ignored. Backward trajectory analysis indicates cross-boundary transport of atmospheric MPs from South Asia play an important role on MPs deposited onto TP glaciers. Analysis further reveals that MPs in glaciers are associated with atmospheric mineral dust deposition. This study provides new data for the investigation of MPs in glaciers of remote areas, and a reference for studying MPs in the ice cores of TP glaciers.