| Polycyclic aromatic hydrocarbons?PAHs?are an important component of fine particulate matter in atmosphere,and pose a greater hazard to the atmospheric environment and human health.The composition characteristics and toxicity of PM2.5-PAHs from different sources are different,which make them have regional differences.Identifying the key toxic substances and their sources is the basis for targeted control to protect human health.However,previous researches are mainly focused on urban environments with complex sources,while concerned the regions where large amounts of coking industries gather.This study set up one sampling site in a typical coking concentrated area-Jiexiu state in Shanxi,and one control site in a agricultural area-Fangshan in Shanxi.PM2.5 samples in different seasons were collected.The toxicity of PM2.5 was investigated by exposing lung cells to PM2.5suspension.The coking-special toxic components were identified through analyzing the correlation between the levels of individual PAH species and toxic indicators such as cell vitality,oxidative stress and inflammation.Based on the results,the PMF receptor model was used to explore the major sources of the above toxic factors,especially the contribution from coking emissions.The aim of our study is to provide experimental evidence for the establishment of targeted control measures to protect human health living in coking polluted areas.The main results were as followed:?1?The average concentrations of PM2.5 in Jiexiu and Fangshan were 202.82?g/m3and 43.43?g/m3,respectively.And the average concentrations of PM2.5-PAHs in Jiexiu and Fangshan were 1239.67 ng/m3 and 154.34 ng/m3.The results showed that the atmospheric pollution status in Jiexiu was much more serious than that in Fangshan.Compared with other cities in domestic and overseas,the concentrations of PM2.5 and PM2.5-PAHs in Jiexiu were significantly higher than those in other cities also.The concentrations of PM2.5 and PM2.5-PAHs in the two study areas had significant seasonal variation characteristics,which were highest in winter,followed by autumn.The levels in spring and summer were the lowest.?2?The monomer distribution of PM2.5-PAHs showed that the contribution of Bb F was the largest,accounting for more than 15%.The monomer distribution in winter was obviously different from other seasons,which is related to the significant increase of coal-burning activities in winter.Jiexiu and Fangshan had relatively similar distribution pattern of ring number,with the contribution of 4-ring and 5-ring PAHs accounting for 68.92%and 77.74%of the total PAHs,respectively.The proportion of high-ring PAHs in spring,summer and autumn was the largest,while the proportion of middle-ring PAHs increased significantly in winter.?3?The health risk of PM2.5-PAHs in the study areas were assessed by the Toxic Equivalent Method and the Incremental Lifetime Cancer Risk Method.It was found that the health risk of PM2.5-PAHs in Jiexiu was an order of magnitude higher than that in Fangshan.Cell exposure model results showed that the cytotoxicity of fine particulate matters in winter was much higher than that in other seasons.Pearson correlation analysis between the levels of individual PAH species and toxic indicators identified seven key toxic factors including Acy,Ace,Flu,Phe,Ant,Fla and Pyr.?4?Source apportionment using PMF receptor model showed that the PM2.5-PAHs in Jiexiu were primarily from coal combustion,accounting for 51.58%,followed by coking sources,accounting for 31.83%,and the contribution of traffic sources was the smallest,accounting for 16.59%.The contribution of coking sources to key toxic factors was 27.17%?92.32%. |
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