DISTRIBUTION, SOURCE IDENTIFICATION AND RISK ASSESSMENT OF POLYCYCLIC AROMATIC HYDROCARBONS IN ARABLE SOILS AT A TYPICAL LONG TERM COKING PRODUCTION BASE IN NORTH CHINA

Coking is a main industrial emission source of polycyclic aromatic hydrocarbons (PAHs) in China. A comprehensive study was conducted of the concentrations, spatial distribution, sources, and the potential human health risks of 16 priority PAHs in agricultural soil within 2000 m of a Coking Plant in Shanxi, North China, which has been in production for more than 20 years. Diagnostic ratios were employed to identify the sources of PAHs. Toxic equivalency factors of benzo[a] pyrene were used to evaluate the health-risk of PAHs. Results showed that the total concentrations of the 16 PAHs ranged from 2297 to 9421 ng/g. The mean total concentrations of 15 relatively stable PAHs (Sigma 15PAHs) in agricultural soil around the coking plant were 6591, 4518 and 2208 ng/g at the distances of 1000, 1000 similar to 1500 and 1500 similar to 2000 m, respectively, Sigma 15PAHs decreased with the increasing distance from the emission source. The 4-5-rings PAHs of fluoranthene, pyrene, benz[a]anthracene and chrysene were the most dominant components with an average percentage contribution of 52.72%. The PAHs in soils were mainly from pyrogenic sources, especially coal combustion. The benzo[a]pyrene concentrations of 7 carcinogenic PAHs accounted for 83% of the total 15 PAHs. The Sigma PAHs(7c) mainly contributed to the potential carcinogenic risk for humans, which declined with distances increasing in 2000 m. Long-term exposure to coking plants potentially induce human health risks.