Size segragated samples were collected during high polluted winter haze days in 2006 in Beijing, China. Twenty nine elements and 9 water soluble ions were determined. Heavy metals of Zn, Pb, Mn, Cu, As, Cr, Ni, V and Cd were deeply studied considering their toxic efect on human being. Among these heavy metals, the levels of Mn, As and Cd exceeded the reference values of National Ambient Air Quality Standard(GB3095-2012) and guidelines of World Health Organization. By estimation, high percentage of atmospheric heavy metals in PM2.5indicates it is an efective way to control atmospheric heavy metals by PM2.5controlling. Pb, Cd, and Zn show mostly in accumulation mode, V, Mn and Cu exist mostly in both coarse and accumulation modes, and Ni and Cr exist in all of the three modes. Considering the health efect, the breakthrough rates of atmospheric heavy metals into pulmonary alveoli are: Pb(62.1%) > As(58.1%) > Cd(57.9%) > Zn(57.7%) > Cu(55.8%) > Ni(53.5%) > Cr(52.2%) > Mn(49.2%) > V(43.5%). Positive matrix factorization method was applied for source apportionment of studied heavy metals combined with some marker elements and ions such as K, As, SO4 2 etc., and four factors(dust, vehicle, aged and transportation, unknown) are identified and the size distribution contribution of them to atmospheric heavy metals are discussed.
PM2.5 and gaseous pollutants(SO2,HNO2,HNO3,HCl,and NH3) were simultaneously collected by Partisol- Model 2300 Sequential Speciation Sampler with denuder-filter pack system in the spring of 2013 in Beijing.Water-soluble inorganic ions and gaseous pollutants were measured by Ion Chromatography.Results showed that the concentrations of NH3,NH+ 4and PM2.5 had similar diurnal variation trends and their concentrations were higher at night than in daytime.The results of gas-to-particle conversion revealed that [NH3]:[NH+4] ratio was usually higher than 1; however,it was less than 1 and the concentration of NH+4 increased significantly during the haze episode,indicating that NH3 played an important role in the formation of fine particle.Research on the sampling artifacts suggested that the volatilization loss of NH+4 was prevalent in the traditional single filter-based sampling.The excess loss of HNO3 and HCl resulted from ammonium-poor aerosols and semivolatile inorganic species had severe losses in the clean day,whereas the mass of NH+ 4was usually overestimated during the single filter-based sampling due to the positive artifacts.Correlation analysis was used to evaluate the influence of meteorological conditions on the volatilization loss of NH+4.It was found that the average relative humidity and temperature had great effects on the loss of NH+4.The loss of NH+4 was significantly under high temperature and low humidity,and tended to increase with the increasing of absorption of gaseous pollutants by denuder.The total mass of volatile loss of NH+4,NO- 3and Cl- could not be ignored and its maximum value was 12.17 μg m-3.Therefore it is important to compensate sampling artifacts for semivolatile inorganic species.
