Status,Source And Risk Assessment Of Polycyclic Aromatic Hydrocarbons In Soil From The Water-Level-Fluctuation Zone Of The Three Gorges Reservoir,China

Polycyclic Aromatic Hydrocarbons(PAHs)are a class of persistent organic pollutants(POPs)with three toxicity that are widespread in the environment,soil is an important sink of PAHs in the environment,through a variety of ways to release into the atmosphere of PAHs,and finally through the wet and dry settlement into the soil.In the Three Gorges Reservoir,because of the circulation pattern of the winter storage and summer discharge,the water level changes in the water level fluctuation zone.The polycyclic aromatic hydrocarbons(PAHs)in the soil will be reentered into the water,which will not only cause soil and water pollution,but also cause great threat to human health.In this paper,the distribution,sources and risk assessment of PAHs in the soil of the Three Gorges Reservoir were studied systematically.The study aimed to understanding the soil contamination status and potential risk posed by PAHs in the soil of the Three Gorges Reservoir,and to providing the scientific basis for pollution control and management of PAHs of the WLFZ of the TGR.The main results are as follows:The results showed that the concentrations of PAHs ranged from 18.40 ng/g to392.29 ng/g(mean 98.11 ng/g)、23.30 ng/g to 259.22 ng/g(mean 73.95 ng/g)in June and September 2012;and 54.00 ng/g to 463.08 ng/g(mean 143.66 ng/g)、63.68 ng/g to558.76 ng/g(mean 175.50 ng/g)in June and September 2013.The concentrations of PAHs in the upstream countries were significantly higher than that in the middle and the lower reaches counties.The PAHs pollution spots in the soil of the water level fluctuation zone are mainly in the upstream,and the content of pollutants is increasing.The compounds of low ring were the major components of PAHs in this area.PAHs concentrations and different ring number PAHs were not significantly correlated with total organic carbon(TOC).By the ratio method,PAHs were mainly derived from coal,biomass and petroleum combustion,followed by oil sources.Ecological risk assessment indicated that the ecological risk of PAHs in the soil of the Three Gorges Reservoir was smaller.Health risk assessment showed that there was an increasing trend of ILCRs in this region.The incremental lifetime cancer risks(ILCRs)ranged from 10-9 to 10-6,The results indicated that the ILCRs of PAHs in the soil of the Three Gorges Reservoir was very small.