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Aerosol Particles from Dried Salt-Lakes and Saline Soils Carried on Dust Storms over Beijing

並列摘要


Characteristics of individual particles from a super dust storm (DS) on 20 March 2002, and those of non dust storm aerosols for Beijing (NDS) and Duolun (DL) (a desert area) are deter mined using a variety of methods. In China, typically the source of aerosols in dust storms is thought to be deserts with aluminosilicates being the main constituent particles; how ever, this does not reflect a complete analysis with our evidence indicating potential alternate dust sources along the storm's transport path. Individual particle analysis of aero sols collected from a super dust storm on 20 March 2002 in Beijing shows that among all the 14 elements measured, only S and C1 have remark able positive correlation. 82.5% of all particles measured contained both S and C1, and the relative mass percent age of S and C1 in these particles is much higher than the aver age of all particles. 62.0% of all particles contained S, C1, and Na, in which the concentration of Na is 1.4 times higher than average. PMF (Positive Matrix Factorization) analysis indicates that NaC1 and Na2SO4 are major components of these particles with S and C1 showing significant positive correlation. More over, SO4(superscript 2-) and Cl(superscript -) also show significant positive correlation in bulk aerosol analysis. XPS (X-ray Photoelectron Spectroscopy) analysis of the surface of aerosols demonstrates that concentrations of Na and S on particles from the dust storm are higher than those from non-dust storm particles in Beijing and also for particles from. It is very likely that particles enriched with S, C1, and Na is from the surface soils of dried salt-lakes and saline soils enriched with chloride and sulfate. This evidence demonstrates that besides deserts, surface soils from dry salt-lakes and saline soils of arid and semi-arid areas are also sources of particulates in dust storms over Beijing.

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