Acid Rain Data and Trends

In this section we summarize recent understanding of acid rain occurrences in various areas of the world. Driven mainly by data availability, we focus on wet deposition in remote areas of the world, in Europe, and in North America. 

Remote Areas Table 20.3 shows rain composition in five remote areas in 1980-81 based on the study of Galloway et al. (1982). 

These results indicate that indeed no single pH value is universally representative of precipitation in the absence of anthropogenic influences. The same is true for the individual compounds in precipitation. This is a direct result of the variability in natural sources of acid-forming compounds and alkaline materials and meteorological variability (wet and dry years, changes in wind flow patterns, low volume rainfall samples, etc.). 

TABLE 20.3 Mean Rain Composition in Remote Areas of the World Based on 1980-1981 Data 

FIGURE 20.9 Annual volume-weighted pH, for Europe for 1985 (Schaug et al. 1987). 

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