| Ambient size-resolved particles in Xuanwei atmosphere were collected in December 2012 and December 2013 by using a Micro-orifice uniform deposit impactor(MOUDI). The polycarbonate filters were used for particle collection. Scanning Electronic Microscopy(SEM/EDS), Inductively Coupled Plasma Mass Spectrometry(ICP-MS), Electron Paramagnetic Resonance spectroscopy(EPR), MTT and DTT assay were employed to identify the morphologies, elemental composition and bioreactivity of size-resolved particles respectively, and Multiple Path Particle Dosimetry model(MPPD) was used to simulate the deposition fraction of the size-resolved particles in human respiratory.Our results showed that the average mass concentrations of the coarse/fine/ultrafine particles in Xuanwei atmosphere collected in December 2012 was 9.20 μg m-3, 18.23 μg m-3 and 12.85 μg m-3, and in December 2013 was.63μg m-3、50.29 μg m-3 and 20.64 μg m-3, respectively. Mass concentration of the ambient particles in different years had obvious variation, the mass levels of those particles in 2013 were higher than those in 2012. Fine particles were the major component of the Xuanwei ambient particulate matters in both 2012 and 2013. The results of SEM/EDS showed that airborne particles in Xuanwei air could be classified into regular and irregular particles according to their morphology and elemental composition.The regular particles primarily consisted of soot aggregates, fly ash and mineral particle. The irregular particles were mostly exsited in coarse particles. The soot aggregates were mainly found in fine particles. The regular mineral particles were the dominant type of particles in the ultrafine particles.The mass concentrations of 29 elements, including Li、Be、Na、Mg、Al、K、Ca、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Ga、As、Se、Rb、Sr、Ag、Cd、Cs、Ba、Tl、Pb、Bi、Th and U, were investigated in Xuanwei size-segregated air particles with ICP-MS. It demonstrated that the highest mass concentration of Al in 2012 particles and 2013 particles with values 4329.53 ng m-3 and 1962.39 ng m-3 and the element mainly distributed in fine and ultrafine particles. The results of ICP-MS results revealed that Pb and Cu had higher mass concentration(the values of Pb and Cu were 32.35 ng m-3, 34.35 ng m-3 and 18.63 ng m-3, 22.31 ng m-3 in 2012 and 2013, respectively) than other elements in minor elements. Both Pb and Cu were anthropogenic elements, Pb dominated in the fine particle fraction and Cu dominated in fine and ultrafine particle fraction. Co, the highest mass concentration in trace metals, mainly resided in coarse and fine particles.Enrichment factor analysis result revealed that elements were easily absorbed in fine particles. Be、Mg、K、Ca、V、Mn、Fe、Co、Ni、Ga、Rb、Sr、Cs and Ba were natural elements, Tl and Pb were considered natural and anthropogenic elements. As、Zn、Se、Ag、Cd and Bi could be enriched in all size ranges and it illustrated those elements were anthropogenic elements.MPPD results demonstrated that the deposition fraction of particles in human respiratory related with particle size range, particles with less than 0.5 μm could be easily deposited in pulmonary region, however particles with more than 0.5 μm deposited in head area. The pulmonary region had the higher deposition fraction than head and tracheobronchial in human respiratory in both years. Cd and Pb could be easily deposited in human respiratory, Fe and Cr had the lowest deposition fraction in 2012 and 2013. The deposition fraction of Zn、Cd and Pb had the higher values in head than that in pulmonary, however, deposition fraction of Cr、Co、Ni and Cu in human respiratory was different. The total deposition dose of major mental elements in 2012 was 1.8 times compared with that in 2013, and both 2012 and 2013 had the same result for the same depositon pattern: pulmonary > head > tracheobronchial.EPR results indicated that the magnitude of free radical intensity caused by size-resolved particles followed these patterns: coarse particles > fine particles > ultrafine particles for 2012 samples and 2013 samples. MTT assay results conclusively showed that cell activity increased gradually with increasing particle size at the same concentration of particles in 2012 and 2013. DTT assay results indicated that DTT activity was the highest in 0.010-0.018 μm and decreased gradually with increasing particle size. The results show a positive correlation between MTT and DTT methods, indicate that the smaller the particle size, the more likely to cause cells to produce reactive oxygen species, the stronger to inhibit the growth activity of cells. The correlation coefficient R2 between the elements and the rate of DTT consumption demonstrated that most elements of particles had no significant contributing to the ratio of DTT consumption, however, several demaged metal elements correlated with the ratio of DTT consumption, such as Zn、Cd、Pb. |
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