Pollution Characteristics, Dry Deposition Fluxes, and Sources for Atmospheric Polycyclic Aromatic Hydrocarbons in the Bosten Lake Watershed

Abstract

Passive air samplers (PAS-PUF) and passive dry deposition (PAS-DD) samplers were applied in the Bosten Lake watershed located in Xinjiang to estimate the atmospheric concentrations and dry deposition fluxes for 15 US EPA priority polycyclic aromatic hydrocarbons (PAHs) during a heating period in 2016 and no-heating period in 2017, respectively. The results showed that the atmospheric PAHs concentrations in the Bosten oasis area ranged from 6.38 ng·m-3 to 245.43 ng·m-3 during the heating period and 2.33 ng·m-3 to 74.76 ng·m-3 during the non-heating period. The highest atmospheric PAHs concentrations were found in the residential area, followed by regions near Bosten Lake and Tazhong. The atmospheric dry deposition fluxes of PAHs in the Bosten Lake watershed ranged from 0.45 μg·(m2·d)-1 to 18.10 μg·(m2·d)-1 during the heating period and 0.25 μg·(m2·d)-1to 8.15 μg·(m2·d)-1 during the non-heating period. During the heating period, the atmospheric dry deposition fluxes in the residential area were significantly higher than those in the regions near Bosten Lake and Tazhong. However, the atmospheric PAHs dry deposition flux in Tazhong was much higher than that in other sites during the heating and no-heating periods. In general, the atmospheric PAHs dry deposition fluxes during the heating period were significantly higher than those during the non-heating period. PAH composition for the atmosphere and dry deposition were dominated by 3 and 4 ring congeners, especially by phenanthrene, fluorine, fluoranthene, and pyrene during two sampling periods. In addition, the congener diagnostic ratio shows that coal and biomass combustion were possible sources of atmospheric PAHs in the Bosten Lake watershed. The forward and backward trajectory analysis based on the HYSPLIT model demonstrated that the higher atmospheric PAH emissions from the residential area would be transported to Bosten Lake, which can affect the aquatic environment of this lake by dry deposition.