Sulfate particles past concentrations

The first major link between the indirect effects of aerosol particles and climate is whether there has been an increase in particles and in CCN due to anthropogenic activities. As discussed in Chapter 2, anthropogenic emissions of particles and of gas-phase precursors to particles such as S02 have clearly increased since preindustrial times, and it is reasonable that CCN have also increased. Ice core data provide a record of some of the species that can act as CCN. Not surprisingly, sulfate and nitrate in the ice cores have increased substantially over the past century (Mayewski et al., 1986, 1990 Laj et al., 1992 Fischer et al., 1998). For example, Figure 14.43 shows the increases in sulfate and nitrate since preindustrial times in an ice core in central Greenland (Laj et al., 1992). Sulfate has increased by 300% and nitrate by 200%. This suggests that sulfate and nitrate CCN also increased, although not necessarily in direct proportion to the concentrations in the ice core measurements. 

Figure 9.30b shows the sites of contact of the corrosion layer with 4BS crystals of the paste not much affected by the H2SO4 flows. A reaction of hydration of the 4BS crystals proceeds and the obtained particles interconnect with the hydroxide in the corrosion layer, after which their surface undergoes partial sulfation by the H2SO4 flows of low concentration, and small PbS04 crystals are formed. 

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