CBSE Class 9 Answered

Acid rain is rain that has become highly acidic due to contact with certain atmospheric gases such as sulfur dioxide and nitrogen oxides. These gases are mainly released by burning of fossil fuels. In the presence of sunlight, these pollutants form sulfates and nitrates that create sulfuric and nitric acids when dissolved in water.

Acid rains can impact aquatic ecosystems by harming individual organisms and by disrupting flows of energy and materials through the ecosystem. Acid deposition causes lower pH and higher aluminum concentrations, which results in the loss of fish and other aquatic species.

Acid precipitation may injure trees directly or indirectly through the soil. High altitude forests are especially vulnerable as they are often surrounded by clouds and fog which are more acidic than rain.

Soil biology can be seriously damaged by acid rain. Many microbes are unable to tolerate low pHs and are killed.

Acid rain can also cause damage to certain building materials and historical monuments.