Temporal and Spatial Variety of Polycyclic Aromatic Hydrocarbons (pahs) Atmospheric Deposition in Chengdu Economic Region, China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous; some of them have been paid more attention due to their carcinogenic and mutagenic properties. Atmospheric deposition is an important process for air-surface exchange of polycyclic aromatic hydrocarbons (PAHs). A yearround bulk (wet plus dry) deposition sampling campaign in mountain, plain, and basin sites was conducted in Chengdu Economic Region (CER), Sichuan Province, which is one of the largest agricultural provinces in China, and the total PAH emission ranked the first in China in 2003 with average emission of 5.35 kg km. The spatial and temporal variations of particle deposition fluxes and the potential influences of climate and landform on the fate of PAHs were discussed.The atmospheric deposition of total PAHs deposition fluxes ranged from 176.8 g m yr to 1138.8 g m yr, with highest flux (1138.8 g m yr) at low mountain region with altitude less than 400 meters (Site S4), which maybe give an evidence of micro-cold-trapping effect in mountains. The deposition fluxes in cold seasons (spring and winter) were higher than in warm seasons (summer and autumn). The flux ratio of heavy molecular weight PAHs (HMWPAHs, 5+6 rings PAHs) in autumn was more than in other seasons. The flux ratio of 4 rings PAHs increased in winter and spring. Contaminant source seasonality and temperature were controlling factors for PAHs seasonal flux characteristics after the discussion on seasonal variations of PAHs and controlling factors.