Pollution Characteristics And Health Risk Assessment On Polycyclic Aromatic Hydrocarbons In PM_2.5 In Huaxi And Nanming District Of Guiyang

Polycyclic aromatic hydrocarbons（PAHs） is a kind of persistent organic pollutants and widely exists in the environment, which have carcinogenesis, tetratogenesis and mutagenesis and do potential harm to the people exposured in the environment for a long time. Guiyang, a captital city in western China, has developed rapidly in the economy during the past 30 years which is associated with the air pollution problem. This paper emphatically discusses how to build a reliable,effective and simply method to detect PAHs in atmospheric PM_2.5 and applied to detect corresponding concentration in parts of Guiyang.According to the results and professional methods, health risk assessment was conducted for residents in parts of Guiyang.1. This research established a reversed phase high performance liquid chromatography gradient elution method of UVD combined with tandem FLD for determinng PAHs in PM_2.5. The detection limits range of16 kinds of PAHs are 1.12².56 μg/L, average recovery rate 73.6⁹0.6%,relative standard deviation 1.44%⁸.83%, which meet the related detection requirements. It has been proved that the method provide the advantages of good accuracy, high reliability, high sensitivity, good separation effeciency and easy operation. It reached the requirements of detection for PAHs in atmospheric PM_2.5.2. By the use of this method, PAHs were detected in atmosphericPM_2.5 from Huaxi district and Nanming district in Guiyang city. The detection results are as follows:（1） The resuls showed that seasonal concentrations of PAHs in winter were higher than in summer and annual average detection concentration of ∑PAHs in Huaxi district is slightly lower than in Nanming district.（2） PAHs detected in PM_2.5 exist mainly as the form of four rings,five rings and six rings. Compared with other seasons, in the winter, the concentration of four rings PAHs increase dramatically while five rings and six rings decrease apparently.（3） The ratio method results indicate that PAHs concentration display noticeable seasonal variation and coal combustion and vehiles emissions are the main source of pollutants. Coal combustion is the main pollution source in the winter, while in the summer vehicle emission is the dominant pollution resouce. The factor analysis shows that coal conbustion and motor vehicle exhaust are the main pollution sources from the factor loading of PAHs in PM_2.5 of two districts,.3. The research on PAHs in PM_2.5 was carried out from adults and children in Huaxi district and Nanming district with health risk assessment method, which was recommended by US EPA and WHO.The results are as follows:（1） Average daily exposure of breathing for adults and childrenwere 1.148E-05 mg/（kg·d） and 7.286E-06 mg/（kg·d） in Nanming district;average daily exposure of breathing for adults and children were1.063E-05 mg/（kg·d） and 6.741E-06 mg/（kg·d） in Huaxi district.（2） The average lifetime cancer of risk resulted from breathing and exposure for adults and children were 3.560E-05 and 2.259E-05 in Nanming district; the average lifetime cancer of risk resulted from breathing and exposure for adults and children were 3.294E-05 and2.090E-05 in Huaxi district. All the values exceed the acceptable maximum risk level for people. It suggested that there should be a potential carcinogenic risk for a long exposure in this environment.（3） The loss of life expectancy caused by breathing and exposure for adults and children are 221.3 min and 140.4 min in Nanming district, the loss of life expectancy caused by breathing and exposure for adults and children are 204.8 min and 129.9 min in Huaxi district.4) Compared with carcinogenic equivalent concentration of PAHs emitted by other sources, the rate of contribution of PAHs from vehicles emission is the highest and exceeded the acceptable maximum risk level for people.