| Popis: |
Particles from four samples of urban particulate matter collected in the U.S.A. were analysed by combined electron microscopy and microanalysis (EMMA). In the case of material collected at Baltimore, Maryland, lead was found to be present only in particles ranging from 0.05μm to about 0.3μm in size. The lead bearing particles did not seem to associate with other particles. Analysis of a fly ash specimen showed no qualitative or significant quantitative variation in chemistry as a function of size for the most prevalent type of particle found. Since it may be crucial to have information about particles smaller than 0.5μm in air pollution studies, EMMA should be included with spectrometric analysis, X-ray diffraction, scanning electron microscopy and electron probe microanalysis as a primary tool for particulate analysis. |
