Distribution Characteristics and Health Risk Assessment of 18 PAHs in a Coking Plant

To investigate the pollution characteristics and health risks of polycyclic aromatic hydrocarbons (PAHs) in coke plant soils, this study focused on a coke plant and set up 260 sampling points. A total of 780 soil samples were collected at different depths according to the contamination status of each point. By analyzing the contents of 18 PAHs in the samples, the overall pollution level of PAHs in the soil of the plant area under different determination criteria, and the contamination status and characteristics of different functional areas were discussed. The health risks associated with the 18 PAHs in the plant area were assessed in accordance with the "Technical guidelines for risk assessment of soil contamination of land for construction" (HJ 25.3-2019). Results show that: (1) The pollution level of this coking plant is relatively high, and the pollution in the plant area shows strong heterogeneity in space. The main PAHs in the plant area are 2-3 rings, accounting for 58.82%, while 4-6 rings accounting for 41.18%. The TEQ_Bap distribution characteristics of the six main risk PAHs within the plant are consistent with the content distribution of the total 18 PAHs (∑₁₈PAHs). (2) Among different functional areas, the sewage treatment area has the most severe pollution, followed by the chemical production area, the coke oven area, the boiler power plant area, the coal storage area, and the office area. The ratios of low- and high-ring PAHs in the various functional areas indicate differences in the sources of pollutants in each region. (3) The main health risk in the plant area arises from the carcinogenic risk of the compounds. After quantifying benzojfluoranthene and benzokfluoranthene separately, the total carcinogenic risk of the 18 PAHs increased by 0.93%-204.46%, and the total carcinogenic risk exceeding points of the 18 PAHs in the plant area increased by 5.