Polycyclic aromatic hydrocarbons (PAHs) in the surface soils of vegetable plots around the Guanting Reservoir
官厅水库周边蔬菜地表土中多环芳烃的污染

Guanting Reservoir is a strategic water resource for the city of Beijing. Forty-eight surface soil samples (0~20 cm) around the reservoir were collected from the Xiaofengying vegetable base, Yanqing County, in November 2008 to investigate the sources and contamination status of polycyclic aromatic hydrocarbons (PAHs) in the surface soil. The origins of the PAHs were determined by analyzing the ratio of isomeric PAH species and by factorial analysis/multiple linear regression. The concentrations of 15 PAH compounds (PAH15) in the soil samples showed normal distribution or lognormal distribution. The geometric and arithmetic means were (118.71±28.63) ng·g-1 (dry weight) and (139.57±85.65) ng·g-1, respectively. Based on the Dutch soil quality standard, 71% of the samples were classified into the low-contamination category. These concentrations were lower than many reported in the literature. The PAH compounds were dominated by 3~4 ring compounds, particularly PHE, FLA, FLO and PYR. The corrected isomeric ratio of FLA/(FLA+PYR) and ANT/(ANT+PHE) showed that the PAHs mainly came from combustion sources.Factorial/multiple regression analysis identified three principal sources, representing (1) coal burning/ vehicle exhaust, (2) biomass combustion/coking, and (3) petroleum burning, which account for 54.0%, 39.9% and 6.1% of the PAHs in the soil analysed, respectively. Therefore, apart from the PAHs from biomass burning in the local region, other PAHs were deposited from distant sources via atmospheric transportation.