Spatial and Seasonal Variation of Polycyclic Aromatic Hydrocarbons (Pahs) Deposition Flux and Sources in Shanghai

Spatial and temporal variations of PAHs deposition flux and sources may significantly facilitate risk evaluations of super magacity in China. A study on polycyclic aromatic hydrocarbons of wet deposition and dry deposition in Shanghai was conducted from January to December, 2019. 17 sites were investigated located in four representative functional areas, covering iron and steel industry (BS), petrochemical industry (JS), central city (CC) and agricultural area (CM). The results showed that atmospheric PAHs level in shanghai was the lowest in autumn and the highest in winter. As industrial area, BS and JS demonstrated higher PAHs deposition fluxes than those in CC and CM sites. Triangle map indicated that the PAHs distribution in winter and spring samples were more homogeneous, suggesting possible common origins, whereas that of summer and autumn seemed to be more dispersed. Isomar ratio and positive matrix factorization model were employed to identify the potential sources of PAHs in specific functional areas. BS was dominated by a high percentage (46%) of coal combustion. In JS site, the petroleum volatilization source percentage was 47.6%. The highest biomass burning (55.3%) contributions were in CM. Vehicle emission (49.3%) was identified as the predominant source of PAHs in CC. This study highlighted that local emission sources have a greater influence on PAHs deposition to specific functional regions in Shanghai.