Aquatic chemistry of acid deposition

The importance of oxidative reactions, gas absorption into water, and the scavenging and partial dissolution of aerosols into water on the formation of acid precipitation were described. Chemical concepts needed to understand the acid deposition process were considered. A stoichiometric model was used to explain that the composition of rain resulted from titration of acids formed from atmospheric pollutants with the bases introduced into the atmosphere. The absorption equilibrium of sulphur dioxide and ammonia was used to represent their interaction with water. Base- and acid-neutralizing capacities were defined to measure residual acidity of acid precipitation and to interpret the interaction of acid deposition with the terrestrial and aquatic environment.