Acid Precipitation in the Northeastern United States: pH and Acidity.

Detailed chemical analyses reveal that acid precipitation (pH < 5.6) in the northeastern United States is caused by the strong mineral acids sulfuric and nitric. There is a large array of other proton sources in precipitation, weak acids and Bronsted acids; however, although these other acids contribute to the total acidity of precipitation, they have a minimal influence on the free acidity (ambient pH) of acid precipitation.