To compare the inorganic chemical compositions of TSP(total suspended paniculate),PM_(10)(particulate matter with an aerodynamic diameter less than 10 μm) and PM_(2.5)(particulate matter with an aerodynamic diameter less than 2.5 μm) in southern and northern cities in China,atmospheric particles were synchronously collected in Dalian(the northern city)and Xiamen(the southern city) in spring and autumn of 2004.The mass concentrations,twenty-three elements and nine soluble ions were assessed.The results show that in Dalian,the mass concentrations of Mg,Al,Ca,Mn and Fe in spring were 4.0-10.1,2.6-8.0,4.1-12,1.2-3.6 and 2.9-7.9 times higher,respectively,than those in Xiamen.The dust storm influence is more obvious in Dalian in spring.However,in Xiamen,heavy metals accounted for 13.9%-17.9%of TSP,while heavy metals contributed to 5.5%-9.3%of TSP in Dalian.These concentrations suggest that heavy metal pollution in Xiamen was more serious.In addition,the concentrations of Na^+,Cl^-,Ca^(2+) and Mg^(2+) were higher in Dalian due to the influence of marine aerosol,construction activities and soil dust.The NO^(3-)/SO_4^(2-) ratios in Dalian(0.25-0.49) were lower than those in Xiamen(0.51-0.62),indicating that the contributions of vehicle emission to particles in Xiamen were higher.Coefficient of divergence values was higher than 0.40,implying that the inorganic chemical composition profiles for the particles of Dalian and Xiamen were quite different from each other.
Yiding MaZongshuang WangYufei TanShu XuShaofei KongGang WuXuefang WuHong Li
Ambient benzene homologues were measured at a site in the northeastern urban area of Beijing, China, from August 24 to September 4, 2012 by SUMMA canister sampling followed by laboratory determination using cryogenic cold trap pre-concentration-GC-MS/FID, and their health risks were also assessed. Daily total benzene homologues ranged from 0.99 to 49.71 μg/m3with an average of 11.98 μg/m3. Benzene homologues showed higher concentrations in the morning and evening than that at noontime. Comparison with previous studies revealed a trend of decrease for ambient benzene homologues probably due to the efective emission control in Beijing in recent years. Vehicular exhaust was the main source while volatilization of paints and solvents also made substantial contributions. Health risk assessment showed that BTEX(benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) and styrene had no appreciable adverse non-cancer health risks for the exposed population, while benzene has potential cancer risk of 1.34E-05. Available data from cities in China all implied that benzene imposes relatively higher cancer risk on the exposed populations and therefore strict control measures should be taken to further lower ambient benzene levels in China.
Lei LiHong LiXinmin ZhangLi WangLinghong XuXuezhong WangYanting YuYujie ZhangGuan Cao
