Distribution, Seasonal Variations and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Foliar Dust of Nanjing, China

Polycyclic aromatic hydrocarbons (PAHs) are of concern for both ecosystem and human health due to their potential teratogenic, carcinogenic, and mutagenic properties. The concentration of ∑16PAHs in foliar dust ranged from 49.4 to 19,018.1 µg kg−1, with a mean value of 7074.5 µg kg−1. There were significant seasonal variations in the concentration of ∑16PAHs, with the concentration in winter being almost twice as high as in summer. Similarly, the differences between PAH profiles in different seasons indicated that they had common sources, which were attributed to the combined effect of regional transport and local emissions. The diagnostic ratios of indicator compounds indicated that PAHs detected in foliar dust originated from a mixture of gasoline vehicle emissions, biomass, and coal combustion in Nanjing. According to the ecological risk classification of ∑16PAHs, the ecological risk caused by PAHs was high since the value of RQ∑16PAHs(MPCs) was ≥ 1 and RQ∑16PAHs(NCs) were ≥ 800. The mean values for RQ∑16PAHs(MPCs) and RQ∑16PAHs(NCs) were 14.8 and 2368.9, which indicated a relatively high ecological risks of PAHs in foliar dust in Nanjing.