Dry deposition of atmospheric polycyclic aromatic hydrocarbons (PAHs) in the southeast suburb of Beijing, China

Dry deposition is an important path for pollutants entering soil and water. In this study, dustfall samples were collected at four representative sampling sites in the southeastern suburb of Beijing from March, 2005 to January, 2006, with a frequency of about once per month, and were analyzed for 16 USEPA priority PAHs using GC/MS. Results showed that the levels of Sigma 16PAHs in dustfall samples were 0.72-40.45 mu g g(-1). The levels of PHE and DahA were the highest and lowest among the 16 PAH compounds, with annual mean values of 2.07 mu g g(-1) and 0.009 mu g g(-1), respectively. Two and three ring PAH compounds were the dominant ones in dustfall samples. The distribution patterns of PAH compounds in different rings in dustfall were different from those in TSP and gas phase. Annual average fluxes of dustfall and PAHs were 1 296.67 mg m(-2) d(-1) and 5.14 mu g m(-2) d(-1), respectively. There were about 423387.6 t dustfall and 1.7 t PAHs depositing onto the surface of Tongzhou District in 2005. Impacts of ground dust, meteorologic parameters, air pollution indexes and deposition velocities on PAHs deposition were discussed. Correlation analysis showed that the fluxes of 2-3 ring PAH compounds had significant positive correlation with the concentrations of 2-3 ring PAH compounds in TSP, and the fluxes of 4 ring PAH compounds had significant positive correlation with those in both TSP and gas phase, while no significant correlation existed between the fluxes of 5-6 ring PAH compounds and the concentrations of 5-6 ring PAH compounds in TSP or gas phase. A regression model was established to estimate the PAH fluxes. (C) 2008 Elsevier B.V. All rights reserved.