Distribution and source of alkyl polycyclic aromatic hydrocarbons in dustfall in Shanghai, China: the effect on the coastal area.

Alkyl polycyclic aromatic hydrocarbons (APAHs) are a group of persistent organic pollutants which are widely distributed in the atmospheric environment. To estimate the seasonal and spatial distribution of APAHs in dustfall in Shanghai, supercritical fluid extraction (SFE) followed by gas chromatography/mass spectrometry (GC/MS) were the analytical methods applied to the dustfall samples collected in this area from Dec. 2004 to Oct. 2005. Forty-one APAHs were found and divided into six groups which were alkyl naphthalenes (ANAs), alkyl phenanthrenes (APHs), alkyl anthracenes (AANs), alkyl fluoranthenes (AFLs), alkyl pyrenes (APYs) and alkyl chrysenes (ACHs). ANAs and APHs were two dominant APAHs in the proportion of more than 50%. The concentrations of total APAHs ranged from 1.6 to 9.0 microg g(-1). The ratios of APAHs to TPAHs (PAHs plus APAHs) fell into the range of 28 approximately 50%. The APAH levels were found to be higher in winter and spring than in summer and autumn. In terms of spatial distribution, concentration of APAHs was found to be higher in western Shanghai than eastern Shanghai. The source analysis showed that dustfall APAHs mainly derived from vehicle emissions and used crankcase oil. The annual fluxes of APAHs and PAHs in dustfall in urban Shanghai were 0.53 approximately 2.97 T and 0.96 approximately 5.34 T, respectively.