| Understanding the physicochemical properties of aerosol particles is important to evaluate their impacts on climate and human health. In order to determine physicochemical properties of aerosols in background regions, we carried out three field campaigns in the Yellow River Delta (YRD) National Nature Reserve in the North China Plain, at Mt. Lu in southern China and around Svalbard island in Arctic. Individual particle samples were collected from January2011to August2013and physicochemical characteristics such as size distribution, morphology, mixing state and chemical composition of atmospheric aerosol particles were analysed through transmission electron microscopy (TEM) coupled with an energy-dispersive X-ray spectrometer (EDS). Besides, we discussed the source and transport pattern of atmospheric aerosol particles.Airborne particles were collected in the Yellow River Delta National Nature Reserve, a background site in the north China plain from January16, to January31,2011. Water-soluble ions in PM2.5and physicochemical characteristics of individual particles were measured in both haze and clear days using two ion chromatographs (ICS-90, Dionex) and through TEM-EDS, respectively. The average concentration of PM2.5was53.99±29.94μg/m3in this period and water-soluble ions composed approximately61.4%of the PM2.5mass on average. The total concentration of SO42-, NO3-and NH4+in PM2.5were18.96±11.53μg/m3, contribute69.8%to89.4%of water-soluble ions. The main particles observed with the TEM-EDS were S-rich and carbonaceous. We also analysed the secondary aerosol particles and found that S-rich, alkaline mineral and NaC1particle coverd with Ca(NO3)2and Mg(NO3)2accounted for about52%of the total particles.72h backward trajectories indicated extensive long-range transportation and low air flow of local region. Long-distance air mass have already accumulated pollutant for about11to19hours before arrival the sampling site. Therefore, the accumulation process near to the ground is a important fact that cause pollution.In this study, aerosol particles were collected at Mt Lu areas in southern China from August to September2011. Six aerosol types inculding sulfate, metal, mineral, fly ash, soot and organic particles were indentified, among which sulfate and metal particles are dominant (>80%) in particle number. The main compositions of fine metal and fly ash are Mn, Fe, Pb, Zn with minor Cr, Co, As, Cd. The result indicated that the metal particles were mainly originated from heavy industries, for example, non-ferrous metal smelting. Size distributions of aerosol particles were also measured through individual particle image analysis system method. The size distributions of sulfate and metal particles show unimodal in the0.05-2μm size range, with the peaks at0.6-0.7μm and0.3-0.4μm, respectively. These fine metal, fly ash and soot particles are completely internally mixed with sulfates. The internally mixed particles can significantly contribute to the CCN in the high-altitude atmosphere. Therefore, it is possible that the widespread metal particles with small sizes would possibly enhance the formation of sulfates, which aggravates the influence of acid rain (cloud) to human health and ecology system in southern China.Individual particle samples were collected around Svalbard island during8-12August,2013. Physicochemical characteristics of2530aerosol particles were analysed through transmission electron microscopy (TEM) coupled with an energy-dispersive X-ray spectrometer (EDS). According to their morphology and chemical composition, arctic aerosol particles were classifieled as five types:sea-salt, S-rich, Fe-rich, carbonaceous and mineral particle.72-h back trajectory analysis showed two types of air mass:ocean type in the arctic region and land type across Svalbard and Greenland. Air mass of the ocean type mainly contained sea-salt particles which accounted for54.7%in this type.95.4%particles were mineral dust in the land type. These results indicated that both natural and anthropogenic aerosol particles in Arctic can contribute to air pollution in some degree. PM2.5mass concentrations in arctic area were estimated using time-density factor according to the known PM2.5mass concentration in Xianghe, China. Finally, we estimated the PM2.5mass concentration ranging from0.55μg/m3to0.72μg/m3in arctic atmosphere.This thesis studied the physicochemical properties of individual aerosol particles in in the Yellow River Delta (YRD) National Nature Reserve in the North China Plain, at Mt. Lu in southern China and around Svalbard island in Arctic and sources of air mass, which provide the data for comprehending the pollution situation in background regions and theoretical basis for making control strategies of atmospheric particles pollution. |
PDF Full Text Request