Distribution and ecological risk assessment of polycyclic aromatic hydrocarbons in agricultural soil of the Chongming island in Shanghai

The concentration and ecological risk of Polycyclic aromatic hydrocarbons (PAHs)were investigated in thirty-three surface soil samples collected from cultivated land in Chongming Island in July 2008. Those samples were extracted using an accelerated solvent extractor (ASE) and determined by GC-MS. Results showed that the concentrations of PAHs ranged between 24.92-1 014.61 ng·g^-1 (dry weight), with a mean value of 192.83 ng·g^-1. The sixteen priority PAHs with exception of Indeno(1, 2, 3-cd)pyrene (IcdP) and Dibenzo(a, h)anthracene (DahA) were all detected in all the samples. The dominant compounds were 2-3ring and 4 ring PAHs, which accounted for 42.6% and 42.2%, respectively, while the 5-6 ring PAHs accounted for 15.7%. PAHs in soil were mainly derived from the fossil oil and the combustion of wood and coal, as determined by the concentration ratio method. The non-industrial combustion and automobile exhaust emissions in Chongming Island may be two of the important sources of PAHs in farmland soil. The analysis of ecological risk showed that the agricultural soil of Chongming Island had low ecological risk.