Pollution Characteristics, Source Identification and Ecological Risk of Polycyclic Aromatic Hydrocarbons in Soil of Water-Level Fluctuation Zone in The Three Gorges Reservoir.

Soil samples were analyzed in the water-level fluctuation zone of Chongqing from the Three Gorges Reservoir for the content and distribution characteristics of polycyclic aromatic hydrocarbons (PAHs). Meanwhile, PAH congeners were analyzed and the potential sources of PAHs in soil were identified by isomer ratio, and the ecological risk of PAHs was evaluated by ecological risk model. The results showed that the content of ∑16PAHs in these regions ranged from 180.2 - 618.0 ng·g^-1 (based on dry mass), and the median value was 421.1 ng·g^-1 (based on dry mass), which was in the medium-low pollution level. All 16 kinds of PAHs were detected, and phenanthrene was the monomer with the highest abundance, which accounted for 19.5% - 32.8% of ∑16PAHs. The content of Σ16PAHs in these different elevations ranged from 281.0 - 794.1 ng·g^-1 (based on dry mass), with the median val- ue of 610.2 ng·g^-1 (based on dry mass), showing an increasing trend with the increase of elevation. Whereas the composition ratio of PAHs was dominated by 3- and 4-rings. The composition of PAHs in soil exhibited a moderate coefficient of variation. Human activities and water level fluctuation had a great influence on the distribution of PAHs in the soil from different elevations. Ecological risk assessment results showed that the fluoranthene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, and benzo[g,h,i]perylene reached high-level risk. The isomer ratios indicated that incomplete combustion of fossil fuels and biomass were the main sources of soil PAHs. The results provided a theoretical reference for the prevention and control of PAHs in Chongqing of the Three Gorges Reservoir. [ABSTRACT FROM AUTHOR]