Chemical mass accounting of urban aerosol

Abstract

A chemical mass accounting technique emphasizing the importance of chemical speciation is developed for analyzing atmospheric-aerosol data. The technique demonstrates that total aerosol mass can generally be characterized from measurements of SO_4, Cl, Br, NO_3, NH_4, Na, K, Ca, Fe, Mg, Al, Si, Pb, carbonaceous material, and aerosol water, the predominant species being SO_4, NO_3, NH_4, Si, carbonaceous material, and aerosol water. Since water is the major species distributed between the gas and aerosol phases, the interrelation between water and electrolytic mass is explored. It is shown that aerosol water is significantly correlated with electrolyte mass. Calculated aerosol ionic strengths lie in the region where the relative humidity/ionic strength relation is most sensitive, thereby suggesting the importance of relative-humidity monitoring during aerosol sampling.

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