Atmospheric emissions of microplastics entrained with dust from potential source regions

Abstract

Atmospheric microplastics play an important role in the microplastic cycle. However, their behaviors in high-altitude remote areas were still poorly constrained. Based on one year of samples from the northeast Tibetan Plateau, we investigated the status of atmospheric microplastics and their relationships with dust. The results indicated that number-based concentrations of atmospheric microplastics were 4.07±2.37 items m^-3 with the maximum in spring, while mass-based concentrations were 0.126±0.152 μg m^-3 with the maximum in winter. Atmospheric microplastics <50 μm accounted for 92.9%, with 95.4% being fragments, emphasizing the pervasive occurrence of small-sized fragmented microplastics in the northeast Tibetan Plateau. Analysis of Lagrangian particle dispersion model combined with potential source contributions revealed that dust emission in potential source regions significantly impacted atmospheric microplastic concentrations. The threshold shear velocity of microplastics and dust exhibited similar values, supporting their co-emissions from potential source regions. Once microplastics are entrained into the airflow, the lower updraft wind speed required for microplastic suspension facilitates long-range atmospheric transport. This study enhanced our insights into the atmospheric microplastic sources and supported future mitigation strategies for microplastic exposure in the remote ecosystem.