Pollution Characteristics,Sources and Health Risk Assessment of Heavy Metals in PM2.5 in Zhaotong City
To study the pollution characteristics,sources and health risks of heavy metals in atmospheric PM2.5 in urban areas of Zhaotong City,four seasons of sampling were conducted at four sampling sites in Zhaotong City in November 2018,January,March and June 2019,and a total of 200 atmospheric PM2.5 samples were collected.Ten heavy metal elements(V,Cr,Mn,Co,Ni,Cu,Zn,As,Pb,Cd)in PM2.5 were analyzed by X-ray Fluores-cence Spectrometer.The results showed that the average concentration of PM2.5 in Zhaotong City was 41.88±27.05 μg/m3 and the total average concentration of 10 heavy metals was 347.27±72.81 ng/m3,accounting for 0.83%of PM2.5.Among them,the concentrations of Cr,Mn,Ni and Zn were higher,which were 75.23±22.97,64.05±8.77,50.22±4.20 and 41.27±24.66 ng/m3,respectively.The seasonal variation of the total average concentra-tion of 10 heavy metals was consistent with that of PM2.5,showing the characteristics of autumn>winter>spring>summer.The results of PMF showed that industrial sources,traffic sources,coal burning sources and dust sources were the main sources of heavy metals in the urban area of Zhaotong City.The annual average contribution rate of industrial sources was the highest,reaching 34.74%.The contribution of dust sources to heavy metals in spring reached 25.19%,which was much higher than that in other seasons,while the contribution of coal sources to heavy metals was the highest in winter,reaching 28.21%.Backward trajectory clustering of air mass and PSCF analysis showed that the southwest direction of Zhaotong City was the main transport path of PM2.5 pollution during the sampling period,and the polluted air mass from Myanmar,northern Yunnan and southern Sichuan cities in China has an important impact on the air quality of Zhaotong City.The results of health risk assessment showed that Mn was a non-carcinogenic risk to all populations.The carcinogenic risk values of Cr for adult males and fe-males reach 4.27×10-4 and 3.66×10-4,respectively,indicating that there was a carcinogenic risk.
Zhaotong Cityheavy metals pollutionPM2.5source of heavy metalshealth risk
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万方数据
