Sources of Excess Acidity in Rainwater...think about it..
What causes such a dramatic increase in the acidity of rain relative to pure water? The answer lies within the concentrations of nitric oxide and sulfur dioxide in polluted air. As shown in Table II and Figure 1, the concentrations of these oxides are much higher than in clean air. Gas
Non-Natural Sources
Concentration Nitric oxide NO Internal Combustion 0.2 ppm Sulfur dioxide SO2 Fossil-fuel Combustion 0.1 - 2.0 ppm Table II
Humans cause many combustion processes that dramatically increase the concentrations of acid-producing oxides in the atmosphere. Although CO2 is present in a much higher concentration than NO and SO2, CO2 does not form acid to the same extent as the other two gases. Thus, a large increase in the concentration of NO and SO2 significantly affects the pH of rainwater, even though both gases are present at much lower concentration than CO2.
