Distribution of Polycyclic Aromatic Hydrocarbons in Coal Gangue and Emitted Gas with Low-Temperature Spontaneous Combustion in Situ

Five coal gangue samples from the Duerping Coal Mine in Shanxi, China, subjected to low-temperature combustion and their emitted gas samples were collected in situ at the combustion temperatures of 23, 33, 49, 57, and 70 °C. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in these samples were determined by high-performance liquid chromatography; these concentrations indicated that with decreasing combustion temperature, ∑ 16 PAHs in coal gangue tend to decrease, whereas ∑ 16 PAHs in emitted gas tend to increase. With the decrease of combustion temperature, the concentrations of Σ 6 LPAHs in coal gangue and emitted gas decreased, whereas the concentrations of Σ 10 HPAHs increased; therefore, the overall toxicity and carcinogenicity increased. The total index of PAHs in the samples ranged from 20.10 to 22.43 with a mean of 21.81. The ratio of Flua/(Flua + Pyr) ranged from 0.34 to 0.97 with a mean of 0.76. Finally, the proportions of Ant/(Ant + Phe), BaA/(BaA + Chr), and InP/(InP + Bghi) were approximately 1. These ratios and the total index of the PAHs could be used to identify the source of PAHs in the atmosphere and soil.