| Polycyclic aromatic hydrocarbons(PAHs)and phthalate acid esters(PAEs)characterized by the effects of carcinogenicity,teratogenicity and mutagenicity pose potential threats for the natural environment and human health.City is the densest area of human activities,its pollution problems have become an increasing concern.With the rapid growth of economy,the situation of urban air pollution is becoming more and more severe,especially for the pollution of particulate matter in winter.This paper selected the city of Xi'an as the study area.Two sampling sites were set up in the Yanta Campus of Shaanxi Normal University within the 3rd ring road near urban center and in the Changan Campus of Shaanxi Normal University outside the 3rd ring road near urban suburb.Sixty-nine atmospheric PM2.5 samples and sixty-four PM10 samples were collected.The concentrations of 16 priority PAHs and six priority PAEs of United States Environmental Protection Department(U.S.EPA)in PM2.5 and PM10 were detected by gas chromatography-hydrogen flame ionization detector(GC-FID)and high performance liquid chromatography-diode array detector(HPLC-DAD).Based on these,the compositional patterns and distribution characteristics of PAHs and PAEs in PM2.5 and PM10 were analyzed,and their environmental sources were identified by using the dignostic ratios,multivariate statistical analysis and receptor models.In addition,according to the exposure evaluation methods in the U.S.EPA,their health risk were evaluated to provide theoretical and practical basises for the protection and management of the urban environment.Through this study,the following conclusions and understandings were obtained:(1)In the south suburb of Xi'an City,the mass concentration of atmospheric PM2.5 ranged from 11.42 to 596.46 ?g·-3 with an average of 110.50 ?g·m-3 being 2.16 times higher than the ambient air quality standard of China(Grade two).The mass concentration of PM10 varied between 45.95 and 702.07 ?g·m-3 with a mean of of 184.77 ?g·m-3 being 1.46 times greater than the ambient air quality standard of China(Grade two).The mass concentrations of PM2.5 and PM10 in the two sampling sites differ.The mass concentrations of PM2.5 and PM10 had the highest values in winter and the lowest values in summer.(2)In PM2.5,the total concentration of 16 PAHs(?16PAHs)ranged from 14.28 to 266.04 ng·m-3 with an average of 62.62 ng·m-3.In PM10,the E16PAHs ranged from 9.69 to 348.99 ng·m-3 with an average concentration of 66.83 ng·m-3.In comarison with the contents of PAHs in atmospheric particles in other cities,the current contents of PAHs in PM2.5 and PM10 in the south suburb of Xi'an are relatively high.The ?16PAHs presented positive correlations with the mass concentrations of atmospheric PM2.5 and PM10.In PM2.5,the total concentrations of 6 PAEs(?6PAEs)ranged from 2.52 to 414.09 ng·-m-3 with an average of 85.61 ng·m-3.In PM10,the ?6PAEs ranged from 15.80 to 475.93 ng·m-3 with an average of 100.45 ng·m-3.Compared with the concentration of PAEs in atmospheric particles in other cities,the current contents of PAEs in PM2.5 and PM10 are at the middle level.The ?6PAEs were positively correlated with the mass concentrations of PM2.5 and PM10.(3)The average contents of Ace,BbF,BkF and BaP in PM2.5 in south suburb of Xi'an were higher than those in PM10,and the average contents of the remaining 12 monomeric PAHs in PM10 were higher than those in PM2.5.The average ?16PAHs in PM10 were higher than those in PM2.5.In addition to Ace,BkF,and DBA in PM2.5,the average concentrations of other monomeric PAHs in the Chang'an campus were higher than those in the Yanta campus.In addition to BKF,the average concentrations of other monomeric PAHs in PM10 were significantly higher on the Chang'an campus than those on the Yanta campus.The ?16PAHs first decreased,and then increased from spring to winter,especially summer having the lowest value and winter presenting the largest concentration.The average ?6PAEs in PM10 were higher than those in PM2.5,the contents of monomer DnBP and DEP in PM2.5 were higher than those in PM10,and the contents of monomer DEHP,DMP,DnOP and BBP in PM10 were higher than those in PM2.5.The average ?6PAEs in PM2.5 in the Changan campus were higher than those in the Yanta campus.The average concentrations of PAEs in PM2.5 except DnBP in Chang'an Campus were significantly higher than those in the Yanta Campus.In addition to DMP and DEP in PM10,the average monomer concentrations of the remaining PAEs in the Chang'an campus are significantly higher than thos in the Yanta campus.The average ?6PAEs in PM2.5 and PM10 in winter were significantly higher than those in other three seasons.(4)The 4-ring PAHs and 5-ring PAHs were dominant in PM2.5 and PM10,especially for BaA and BbF.In winter,the proportion of high ring PAHs increased and the low ring PAHs decreased.The PAEs in PM2.5 and PM10 were controlled by DEHP and DnBP,especially for DnOP in PM10.The percentages of DnOP and BBP to the ?PAEs in atmospheric PM2.5 and PM10 in the Changan campus were relatively high,while the proportion of DnBP in atmospheric particles in the Yata campus was reltively higher.The average ?6PAEs in PM2.5 and PM10 in winter were significantly higher than those in other three seasons,especially for DEHP,DnOP and DnBP.(5)The results of source analyses showed that PAHs in PM2.5 and PM10 were contributed to typical coal combustion and motor vehicle exhaust.PAEs in PM2.5 and PM10 were mainly related to the widespread usage of plasticizers.(6)PAHs in PM2.5 and PM10 had no obvious non-carcinogenic health hazard to the general population.The carcinogenic risk of human exposure to PAHs in PM2.5 and PM10 was within acceptable range.The total carcinogenic risk of 7 carcinogenic PAHs in PM10 was higher than that in PM2.5.The average daily dose of human exposure to PAEs in PM2.5 and PM10 was lower than reference dose(RfD)of U.S.EPA and tolerable daily intake(TDI)of European Union.PAEs in PM2.5 and PM10 had no obvious non-carcinogenic health hazard to the general human.However,the risk of children was higher than that of adults.The carsinogenci risk indice of human exposure to BBP and DEHP in PM2.5 and PM10 were below 10-6,indicating that the carcinogenic risk was negligible.The non-carcinogenic risk of PAHs and PAEs in PM2.5 and PM10 in winter was higher than that in the other three seasons.,and the risk of cancer in winter was much higher than that in the other three seasons. |
PDF Full Text Request