| Polycyclic aromatic hydrocarbons(PAHs),as a group of ubiquitous persistent toxic substances,due to their moderate vapor pressure,low solubility and reactivity,mainly are from incomplete combustion of fossil fuel and biomass.Amounts of researchers are focusing on PAHs,a carcinogenic and mutagenic class of compounds.Hexi Corridor region,an area with large population and huge energy consumption,is an important commodity grain and heavy industrial base,in which PAHs pollution is very obvious.By now,the studies about the concentrations,source indentification,and lung cancer risk induced by the inhalation of atmospheric PAHs in Hexi Corridor region is very lack.Therefore,this study firstly combines the passive air samplers and GC-MS to analyze the atmospheric(mainly gas phase)PAH concentrations.Then source,the lung cancer risk from inhalation of atmospheric PAH was addressed by the total equivalent toxicity of(Benzene[a]pyrene,B[a]P)and risk assessment methods from WHO(the World Health Organization).In this study,the PAHs included 16 congeners recommended by U.S EPA(the USA Environmental Protection Agency).The results were listed as follows:The PAHs with 2?4rings were detected in almost all of the sampling points,however,the PAHs with 5?6 rings were detected in the part of some sampling points.Atmospheric PAH(mainly gas phase)concentrations in the Hexi Corridor region ranged from 0.129ng/m3 to 22.516ng/m3(5.634ng/m3),which were at a lower level compared with other regions in China..The seasonal variation of ?16-PAHs showed that the concentration of atmospheric ?16-PAHs were highest in winter,followed in spring and summer.The PAHs with 2-4 rings accounted for more than of 90%?16-PAHs,Naphthalene(NAP)and the PAHs with 3-ring were concentrated in the gas phase,The PAHs with 4-ring were greatly affected by temperature,and that with higher and lowest concentration levels were in summer and winter,respectivetly.For the spatial distribution of?16-PAHs in the Hexi Corridor region,the higher concentration of?16-PAHs were mainly concentrated in Zhangye,Jiuquan,and Wuwei,followed by Tianzhu,Guazhou,and Jinchang,and the lowest concentration was in Minqin,which may be related to the distribution of industrial structure and the population.The difficience between urban and rural area was not significant,however,the atmospheric PAHs in urban and rural area were far greater than that in the background sites.The more PAHs with higher ring number were in rural,which may due to the input external PAHs by the strong wind.In general,for the sources of atmospheric PAHs,the value of FLA/(FLA+PYR),and IcdP/(IcdP+BghiP)can be used to identify the source of PAHs.In this study,the results indicated that the PAHs in the Hexi Corridor region were mainly from the combustion of coal,biomass and liquid fossil fuel.Principal component analysis showed that the main source of atmospheric PAHs were combustion of the coal,liquid fossil fuels,coke,biomass and natural gas source.The source exhibited the obvious seasonal variation,however,the combustion of liquid fossil fuels and coke has become the major source of PAHs in the Hexi Corridor region.The B[a]P equivalent toxicity and the quantitative risk assessment methods recommended by WHO were used to assess the risk of lung cancer induced by inhalation of atmospheric PAHs.The result showed that the lung cancer risk was from 3.48 × 10-7 to 2.61 × 10-6 in the Hexi Corridor region,which were lower than the acceptable cancer risk range(from 10-6 to 10-4)recommended by U.S EPA and other regions.The lung cancer risk induced by inhalation of atmospheric PAHs in winter(2.61×10-6)was higher than that in summer(3.48×10-7),and the lung cancer risk in urban was higher than rural and background sites.The highest and lowest lung cancer risk was in Zhangye and Minqin,respectively,and the lung cancer risks induced by inhalation of atmospheric PAHs were at the relative safe level in the Hexi Corridor region. |
PDF Full Text Request