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Comparisons of urban and rural sites in close proximity to one another demonstrate, not surprisingly, that urban PM concentrations are greater than rural ones, particularly for coarse PM. This is mirrored by an enrichment in urban areas in the concentration of all inorganic elements and ions assayed for. There are several elements/ions for which the urban-rural difference is disproportionately greater than the total mass difference, however, indicating that these constituents are particularly enriched in urban areas (Ca, -, Fe, Al, Mg, Zn, Ti, Mn, V, Pb, Ni). This pattern is Si, NO3 most likely attributed to the greater suspension of road dust, and more intensive industrial and combustion activity in urban areas.
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