Microplastic Characteristics in Equus kiang (Tibetan Wild Ass) Feces and Soil on the Southern Tibetan Plateau, China

Based on microplastics found in the soiland wild ass feceson the remote Tibetan Plateau, the source, transportation process,and environmental hazards of microplastics are further clarified. Microplastics (MPs) are emerging pollutants, and limitedresearchhas focused on their exposure to terrestrial wildlife and transportmode on the remote Tibetan Plateau (TP). Therefore, we investigatedMPs in the southern soil and feces of Equus kiang (Tibetan wild ass), a species peculiar to the TP, which is knownas the "third pole." We found that MP median abundanceswere 102 and 4.01 particles/g of dry feces and soil, respectively.In both media, the MP morphology mainly comprised & SIM;50 & mu;mslender fibrous particles. In total, 29 MP types were identified inthe feces, compared to 26 types in the soil. Among them, the acrylatecopolymer (35.9%) and polyurethane (24.9%) were predominant in thefeces, while polyurethane (22.5%) and silicone (20.4%) were predominantin the soil. After ingesting MPs at one location, E.kiang may become a source of MP pollution when movingto other meadows on the TP. The potential MP transport flux of a herdof 20 kiangs has been estimated at 1736 particles m(-2) a(-1). A unique "source-sink-source"MP transport model comprising an "atmospheric deposition-vegetation-feces-atmosphere"cycle on the TP was observed based on atmospheric transport simulationsand terrestrial food chain transfer processes. Owing to human settlementsin south and East Asia adjacent to the TP, atmospheric long-distancetransmission is an essential route for MPs to enter the TP.