Polycyclic aromatic hydrocarbons in fine road dust from a coal-utilization city: Spatial distribution, source diagnosis and risk assessment.

Coal combustion can release large amounts of polycyclic aromatic hydrocarbons (PAHs), which persist in various environment matrices (e.g., road dust) and hence cause the carcinogenic risk to human health. In this study, an exhaustive characterization of road dust samples coupling their physicochemical characteristics and stable isotope compositions (δC and δN) was conducted to evaluate the source, level, spatial distribution, and carcinogenic risk of PAHs in a typical coal-utilization city. Concentrations of Σ PAHs ranged from 605.5 to 25,374.3 ng/g with a mean concentration of 4083.0 ng/g. Pollution levels of sites around the coal-fired power plant (Zone 1) were significantly higher than those in other zones (p < 0.05). PAH concentration showed significant correlations with both C and N fractions (p < 0.01). Compositions of δC and δN in road dust coupled to principal component analysis and the partitions and diagnostic ratios of PAHs contributed to associating road dust to several local sources of contamination. Coal combustion and vehicular exhaust were major sources of PAHs around the power plant and urban area. Results of incremental lifetime cancer risk showed 81.5% of all sampling sites suffered potential risk (>10) for both adults and children, while children around the power plant suffered the highest risk. Despite the estimation of only potential risk being posed by PAHs in road dust, human exposure to the various environmental matrices, scientific and systematic assessment of carcinogenic risks by PAHs in the total environment warrants further investigations.