Temporal-spatial Distribution and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Soil of Xiangxi Bay in Three Gorges Reservoir Area

The US Environmental Protection Agency has listed 16 polycyclic aromatic hydrocarbons (PAHs) for priority control. Soil samples from Xiangxi Bay in the Three Gorges Reservoir Area (the water fluctuation zone, WLFZ; upper edge of water fluctuation zone, UEWLFZ; sediments) were analyzed for the concentration of these PAHs, using high performance liquid chromatography (HPLC). The results showed that the soil samples of Xiangxi Bay could be ranked, based on the concentration of PAHs, in the following order: UEWLFZ>WLFZ>sediment. The composition of PAHs varied from the three regions, with 3- and 4-ring PAHs dominating in sediments and 4- and 5-ring PAHs dominating in soil from the WLFZ and UEWLFZ. The composition of PAHs in soil from the WLFZ exhibited a higher coefficient of variation and a weaker correlation with the composition of PAHs in soil from the UEWLFZ and sediment. Soil from the three regions showed varying seasonal distributions of PAHs, which is closely related to the quantity and types of energy consumption in each season. PAHs in sediment from sites at the same altitude showed no evident differences, whereas WLFZ and UEWLFZ soil had higher levels of PAHs at the sites near Xiakou Town and the Yangtze River Estuary. Isomer ratio analysis showed that the sources of PAHs in Xiangxi Bay vary between seasons and regions, with incomplete combustion of fossil fuels and biomass forming the main sources in the soil of Xiangxi Bay. The lifetime carcinogenic risk assessment shows that PAHs in sediment, WLFZ, and UEWLFZ have a potential risk to human through ingestion and dermal contact, with PAHs in the soil of UEWLFZ posing the highest carcinogenic risk. The results provide a theoretical reference for the prevention and control of contamination by PAHs in Xiangxi Bay of the Three Gorges Reservoir area. © 2021, Science Press. All right reserved.