Atmospheric Chemistry of Automotive Lead

Abstract

Techniques based upon X-ray powder diffraction (XRD) have been developed for the identification of lead compounds present in ambient air polluted by vehicle exhaust. Three of the compounds identified are known to be present in automobile exhaust: PbBrCl, PbBrCl-2NH4Cl, and α-2PbBrCl-NH4Cl. The other compounds-analyzed were PbBrCl-(NH4)2BrCl, PbSO4, and PbSO4-(NH4)2SO4, the latter being the predominant form of lead at four of five sampling sites. In laboratory experiments designed to elucidate the formation of these compounds, vehicle-generated PbBrCl was exposed to a range of gaseous and particulate pollutants and the products were examined by XRD. The major process affecting primary lead particulates was found to be coagulation with ambient aerosol accompanied by reaction of PbBrCl with neutral and acid sulfates. © 1979, American Chemical Society. All rights reserved.