Abstract
By using two techniques to enrich the lead fraction of urban aerosol, the authors have identified the major components with the use of X-ray powder diffraction (XRD). The XRD results for Lancaster and Preston shown in a table indicate the persistent presence of (NH sub(4) ) sub(2) SO sub(4) [small solid circle] PbSO sub(4) , together with lesser amounts of PbSO sub(4) . The presence of this compound in the environment has not been reported previously. It is believed that (NH sub(4) ) sub(2) SO sub(4) [small solid circle] PbSO sub(4) is an intermediate in the conversion of vehicle-emitted lead halides to PbSO sub(4) , formed by reaction with atmospheric ammonia and acid sulfates. Although the results presented refer to an atmospheric aerosol aged by as much as 48 hr during high-volume sampling, they are thought to provide the best available guide for selection of compounds to be used in respiratory uptake studies.