Contamination characteristics and risk assessment of polycyclic aromatic compounds in soil from industrial park of Wuda District, Inner Mongolia, China

Industrial Park of Wuda District is typical of industrial parks associated with coal bases in North China. Previous studies on this industrial park have focused mainly on inorganic components, such as mercury, fluorine, and water-soluble ions, with little research on polycyclic aromatic compounds (PACs). In this study, the contamination characteristics and potential health risks of alkyl polycyclic aromatic hydrocarbons (aPAHs) and 16PAHs in soil of the industrial park were examined. Under the combined influence of its own enterprises and the upwind coal fire area, the average concentration of sigma PACs was 10,176 mu g center dot kg(-1) and ranged from 177 to 42,794 mu g center dot kg(-1), exceeding the threshold for severe pollution. The average concentration of aPAHs was 7146 mu g center dot kg(-1), which was approximately twice that of the 16PAHs (3029 mu g center dot kg(-1)). The parent 16PAHs were dominated by medium and high carbon rings, while the aPAHs were dominated by alkylnaphthalenes and alkylphenanthrenes. PACs were concentrated in areas of heavy polluting enterprises such as coal chemical industries and coal-fired power plants that generate point source pollution. Using the characteristic ratio method and positive matrix factorisation (PMF) analyses, it was inferred that the study area was mainly affected by petroleum sources (coal and weathered coal gangue particles) and coal fire residue, followed by wastes from coal and biomass combustion. Coal coking and transportation sources have had fewer impacts. Additionally, the toxicity levels of PACs in the soil of the industrial park exceeded regulatory thresholds. The incremental lifetime cancer risk (ILCR) was in the range of 1.0 x 10(-7) to 1.7 x 10(-5), indicating that the PACs in the industrial park pose a potential threat to human health. Owing to the presence of publicly accessible areas affected by coal mining, coal fire, and industrial parks in North China, the potential for widespread PAC pollution is worth consideration and investigation.