| Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous constituents of particulate matter and well-known to be carcinogenic and mutagenic. PAH contamination is a matter of great public health concern all over the world. The information of this study is important for atmospheric organic pollution control and environment management. In this study, PM2.5 and PM10 samples were collected at six sampling sites, Monitoring Station of Yuxi(MS), Dongfeng Reservoir(DF), Yuxi No.1 middle school(YX), Dayingjie Town(DY), Yanhe industrial park(YH), Hongta Cultural and Sports center(HT) in Yuxi city during August 2014 to July 2015. According to the analysis the main conclusions are as follows:(1) Concentrations of PAHs are different at six sampling sites, For PM2.5, the highest concentration was found at DY site, followed by YH, HT, MS and YX site, the lowest concentration detected was DF site. For PM10, the highest concentration was found at DY site, followed by YH, YX, MS and HT site, the lowest concentration detected was DF site. The proportions of various rings PAHs to the total PAH concentrations are not the same at six sites. At DF sites, the concentration of 4-ring PAHs was the highest, followed by 5-ring,6-ring PAHs,2-and 3-ring PAHs was the lowest. For other sites, the concentration of 4-ring PAHs was the highest, followed by 2-and 3-ring PAHs,5-ring,6-ring PAHs was the lowest.(2) PAHs concentrations presented a clear seasonal pattern and which is similar between PM2.5 and PM10. The highest concentration was found in winter, autumn and spring followed, the lowest concentration was in summer. For different rings of PAHs, the concentration of 2-and 3-ring PAHs was the highest in summer, spring and autumn followed, the lowest concentration was in winter. The other rings is consistent with the distribution of PAHs concentration.(3) Result of health risk assessment of PAHs showed, for both coarse and fine particles, the concentrations of BaP at DY site were exceeded the national ambient air quality standard (2.5ng/m3) in China. In addition, the levels of BaP in autumn and winter are higher than spring and summer which is an alarming signal for pollution risks in relation to human health.(4) The results obtained from diagnostic ratios for six sampling sites showed that traffic emission(gasoline engine and diesel engine), coal combustion, liquid fossil fuel combustion and wood(biomass) combustion are the main source of PAHs in Yuxi.(5) The main sources of PAHs in PM2.5:traffic emission(44.62%) and coal combustion(35.52%) for spring; traffic emission(50.92%), biomass combustion(21.18%) and coke combustion(9.29%) for summer; traffic emission(58.21%), biomass combustion(10.65%) and coke combustion(9.90%) for autumn; traffic emission(56.70%) and coke combustion(11.48%) for winter.(6) The main sources of PAHs in PM10:traffic emission(47.97%) and coal combustion(28.66%) for spring; traffic emission(51.67%), biomass combustion(20.03%) and coke combustion(9.44%) for summer; traffic emission(62.08%) and biomass combustion(23.93%) for autumn; traffic emission(58.83%), biomass combustion(10.76%)and coke combustion(9.91%) for winter.(7) Results obtained from diagnostic ratios associated with PCA revealed that traffic emission is predominant source in Yuxi. Liquid fossil fuel combustion, coal combustion, coke combustion and wood(biomass) combustion are sources of PAHs in Yuxi.(8) The concentration of PAHs in PM2.5 and PM10 was negatively related to temperature, and positively correlated with wind speed. The input of air mass from south and southwest has great influence to PAHs concentration. This suggested that the pollution of Southeast Asia such as Vietnam, Laos and Burma is the cause of variation of PAHs concentration in Yuxi. Meanwhile the input of Qujing, Xuanwei area and Guizhou is one of contributor of PAHs concentration. |
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