Sulfur aerosols, coarse

Fiber-bed scrubbers are used to collect fine or soluble particulate matter or as mist eliminators to collect liquid aerosols, including inorganic (e.g., sulfuric acid mist) and volatile organic compounds. Insoluble or coarse PM will clog the fiber bed with time, and VOCs that are difficult to condense will not be collected efficiently. 

As an indication of the effect of dust storm episodes on the aerosol concentration in the valley, the per cent Increase in the weekly total mass, coarse sulfur, chlorine, silicon, and iron concentration during a dust storm was computed. In addition, the absolute Increase in these quantities was also computed. The results of this analysis are shown in Table II. These data also indicate that a significant increase in aerosol concentration due to suspended lake bed materials occurs as far downwind as Independence. In order to quantify this effect, the sulfur to iron (S/Fe) and chlorine to iron (Cl/Fe) ratio at each site was examined. At Keeler, all the coarse sulfur and iron measured at the sampling site are suspended from the lake bed. At any site... 

The last anion to be discussed is nitrate. In the marine aerosol, nitrate is associated mainly with coarse particles. This fact is apparent in Fig. 7-21, but it has also been observed by Savoie and Prospero (1982). Sea water contains insignificant amounts of nitrate, so that the particulate nitrate must derive from the gas phase, that is, from gaseous nitric acid. As a gas-to-particle conversion process, one would expect the condensation of nitric acid to take place in the accumulation mode. The volatility of HN03 is much greater than that of H2S04, however. It appears that the condensation of sulfuric acid prevents the simultaneous condensation of nitric acid in the same size range. In this connection one should remember that with... 

Continental aerosol particles contain a significant fraction of minerals. The insoluble fraction consists mainly of the major crustal elements silicon, aluminum and trivalent iron, which occur as alumino-silicates, quartz, and iron oxides. Elements that are eluted from minerals by water are sodium, potassium, calcium (inpart), and magnesium. The water-soluble inorganic salt ftaction is dominated by am-monimn sulfate. Again, sulfate arises from the oxidation of sulfur dioxide, both by gas-phase and by aqueous phase reactions. Whereas the mineral components are mainly found in the coarse particle size range, ammonium sulfate resides mainly in the accumulation mode. Nitrate occurs partly in association with ammoniirm in the accumulation mode, and partly together with sodiirm and other cations in the coarse particle mode. Thus, nitrate often shows a bimodal size distribution. 

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