Distribution and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons and Heavy Metals in Coking Sites in China

Coking is a heavy industry in China, and its serious impact on the ecological environment in the production process cannot be ignored. This study collected the latest pollution data of the coking industry sites in various regions throughout China, reflecting the soil pollution status of the coking industry sites in the country as a whole. The ecological risks of the 16 polycyclic aromatic hydrocarbons (PAHs) in coke soils were evaluated and analyzed using the quality benchmark method and the toxicity equivalent method. The "Background Value of Soil Elements in China" was used as the reference standard, and the geo-accumulation index method and the potential ecological risk assessment method were used to evaluate the ecological risks. The ecological risks of various heavy metals were evaluated and analyzed. The results show that the M-ERM-Q value calculated by the quality benchmark method for coking site soils in all regions of the country was greater than 1.51, which indicates a high ecological risk, and the northern region had the highest risk level. According to the Dutch soil quality standard, the toxicity equivalent method revealed that the total toxicity equivalent concentration of 10 PAHs was greater than the Dutch standard, and thus the soil is in a polluted state. The ∑10TEQ in the northern region was much larger than the Dutch standard, which is consistent with the evaluation result of the quality standard method, which showed that Cd and Hg were the main pollutants in the coking site, and the other elements were relatively less harmful. The evaluation of potential ecological risks showed that the pollution of coking sites in northern regions is relatively serious, especially in the Shanxi and Hebei areas where the soil heavy metal damage was the most serious, reaching a strong level. © 2021, Science Press. All right reserved.