An In‐Depth Characterization of Urban Aerosols Using Electron Microscopy and Energy Dispersive X‐Ray Analysis     

Haider A. Khwaja  Pravin P. Parekh  Adil R. Khan  Daniel L. Hershey  Ronaq R. Naqvi  Abdul Malik  Khalid Khan 《洁净——土壤、空气、水》2009,37(7):544-554

The physical and chemical characterization of aerosols from three large cities, Karachi and Islamabad, Pakistan, and New York City (NYC), USA, was investigated. A scanning electron microscope equipped with an energy dispersive spectrometer (EDS) was used to determine particle morphology and elemental composition of the samples. A Bruker Spirit system in combination with a Sahara detector provided both computer controlled Automated Chemical Classification (ACC) and digital mapping features for analysis purposes. The use of these two features to characterize the elemental composition, particle size, and to determine specific classes or source types is described in this paper. Filters were analyzed for the following elements; Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Sr, Y, Zr, Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, La, Au, Hg, Tl, Pb, and U. The EDS work was qualitative not quantitative. Seven source types (mobile, cement, soil, steel mill, fossil fuel, sea salt and biological) contributed to particulate matter in the ambient air of both cities in Pakistan, whereas there were eight source types (diesel, road dust, automobile, iron, residual fuel oil, sea salt, ammonium sulfate and ammonium nitrate) for NYC. For all three urban centers, vehicular traffic emissions were the main contributor to particle number. Diesel emissions from trucks and buses were relatively more prominent in NYC aerosols, while gasoline emission from automotive exhaust was dominant in the two cities of Pakistan. The cement/limestone component from local cement industries was very evident in both particle surface characteristics and number for both Karachi and Islamabad, but not in NYC air. Sea salt aerosols were seen in the two coastal cities, Karachi and NYC. It was also witnessed in Islamabad aerosols and was attributable to the mining of rock salt at the world's richest salt mine, Khewra, situated upwind from the city.  相似文献