Chemical Speciation of Lead Compounds in Street Dusts

Abstract

Street dusts have been sampled at a variety of sites in England. The highest concentrations of lead were often found in the smallest (<38 μm) size fraction, with lower concentrations but greater masses of the metal associated with the larger particle size fractions. Lead compounds were preconcentrated by magnetic and density gradient separation, and identified by X-ray powder diffraction. Six lead species were found : PbSO4, Pb0, PbSO4-(NH4)2SO4, Pb3O4, PbO-PbSO4, and 2PbCC'3-Pb(OH)2. The most frequently observed compound was PbSO4, and its presence is explained by the weathering of PbSO4-(NH4)2SO4 deposited from the atmosphere. Elemental lead is apparently associated with sites at which vehicles are started from cold. It is concluded that only a minor proportion of the lead present in a street dust exists in a crystalline form susceptible to X-ray diffraction (XRD) analysis. © 1980, American Chemical Society. All rights reserved.