Identifying Tracing Species from Source Regions of PM 2.5 on the Tibetan Plateau by Integrating Measurement and Modeling

The atmospheric environment of the Tibetan Plateau is significantly sensitive to pollutants transported from regions with intensive anthropogenic activity. It is therefore critical to identify source regions and transported air pollutants on the Tibetan Plateau. The present study developed a method to link multiple pollutants measured at receptor sites on the Tibetan Plateau to their source regions by integrating measurements and modeling. Ground-based measurements of over 150 species in fine particulate matter (PM 2.5 ) at the Nam Co Station were conducted for one year. Meanwhile, contributions from different source regions to PM 2.5 in each sample were quantified by using an emission inventory-coupled Lagrangian box model. The findings indicated that specific source regions were associated with distinct chemical species and sources. In the premonsoon season, transport from the northwestern South Asia was related to enhanced concentrations of black carbon, organic carbon, K +, anhydrosugars, Pb, and Zn. This suggested a strong influence from intensive biomass burning and industrial activities. However, increased contribution from the northwestern China to PM 2.5 was associated with increased concentrations of low-molecular-weight polycyclic aromatic hydrocarbons, Cl –, and several anthropogenic metals, reflecting impacts from mixed industrial and residential sources. During the monsoon season, concentrations of highly oxidized secondary organic aerosol (SOA) species increased with contribution from regions south of the receptor site, highlighting the importance of aged SOA in this season. The findings in this study not only improve our understanding of how transport from different regions shapes atmospheric composition in the Tibetan Plateau but also offer a new approach to investigate impacts of long-range transport on remote environments.