Abstract: To investigate the soil pollution characteristics caused by coking industry production activities, a total of 1 437 soil samples were collected from three abandoned coking plants in Beijing, Chongqing and Taiyuan, with a maximum sampling depth of 40 m. 16 polycyclic aromatic hydrocarbons (PAHs) that are in the controlling list of US EPA was determined via gas chromatography-mass spectrometry (GC-MS). The maximum contents of ΣPAHs of the three coking plants were 10 647.2 mg·kg^-1(Beijing), 39 332.7 mg·kg^-1 (Chongqing)and 19 381.9 mg·kg^-1 (Taiyuan) respectively. The results indicate that the soils were severely contaminated by PAHs. Toxic equivalent factors (TEF) show that the carcinogenic high-cyclic PAHs were main toxic substances that accounts for more than 90% of the total toxicity contribution. The maximum concentrations of the eight PAHs, preferentially controlled according to the GB 36600-2018, decreased rapidly with the increase of depth. The decrease rate in the soil in the Chongqing coking plant was significantly lower than that of the other two sites, and this phenomenon was more obviously for high molecular weight PAHs. The PAHs derived from coal combustion in the three coking plants accounted for 88.46%-90.38% (Beijing), 83.56%-98.17% (Chongqing) and 74.56%-92.96% (Taiyuan), respectively. The PAHs pollution sources in the soil of the coking plants still exist and include a small part of oil spills and burning. Among the three sites, the maximum proportions of 8 kinds of pollutants, which exceeded the national first-class and second-class control values, are 8.23% and 5.18% (Beijing), 15.34% and 9.77% (Chongqing), and 13.72% and 8.68% (Taiyuan). In addition, the risk levels of the eight PAHs in Beijing and Chongqing were higher than that in Taiyuan. In summary, the results illustrate that the soil of the former coking plants still have high concentration of PAHs in the depth range of 0-20 m. The pollution characteristics of PAHs in the soil of coking plant sites were closely related to the locations and formation conditions. Formation conditions may largely affect the distribution and migration of PAHs in the soil, and the impact on high-ring PAHs were smaller. The results of the study may provide basis for soil remediation and environmental risk assessment of other coke-industry contaminated sites.

Key words: soil, coking plant, polycyclic aromatic hydrocarbons, pollution, toxicity, health risk