Spatial origin analysis on atmospheric bulk deposition of polycyclic aromatic hydrocarbons in Shanghai.

Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) onto soil threatens terrestrial ecosystem. To locate potential source areas geographically, a total of 139 atmospheric bulk deposition samples were collected during 2012–2019 at eight sites in Shanghai and its surrounding areas. A multisite joint location method was developed for the first time to locate potential source areas of atmospheric PAHs based on an enhanced three dimensional concentration weighted trajectory model. The method considered spatial and temporal variations of atmospheric boundary layer height and homogenized all results over the eight sites via geometric mean. Regional transport was an important contributor of PAH atmospheric deposition while massive local emissions may disturb the identification of potential source areas. Northwesterly winds were associated with elevated deposition fluxes. Potential source areas were identified by the multisite joint location method and included Hebei, Tianjin, Shandong and Jiangsu to the north, and Anhui to the west of Shanghai. PM and SO 2 data from the national ground monitoring stations confirmed the identified source areas of deposited PAHs in Shanghai. [Display omitted] • Significant declining trends of PAH deposition fluxes were observed in Shanghai. • Local emission accounted for 25–73% of the total deposition fluxes. • Regional transport from the northern and western parts of China had a great impact. • A multisite joint location method is proposed to screen emission areas of PAHs. • It provides an evidence to support effectiveness of the Clean Air Action of China. [ABSTRACT FROM AUTHOR]