Acid Rain, Dry deposition and wet deposition
Normal Rain water is already slightly acidic, because it reacts with Carbon dioxide in the air. The product of this reaction is a very weak acid called carbonic acid. The normal acidity of rain water is approximately 5.3 - 6 Ph. Acid rain or Acid deposition on the other hand, is below this. Acid rain is a form of precipitation, where acidic pollutants such as, Sulphur Dioxide and Nitrogen oxide, rise high into the atmosphere. These pollutants then react with oxygen and water to form a higher concentration, of far more acidic substances known as, Nitric acid or Sulphuric acid. These acidic substances can travel for hundreds of kilometres until they finally fall to the earth's surface.
Acid Rain is a form of wet deposition, where the wind blows acidic substances to wetter areas. This then falls to the Earth's surface in the form of rain, sleet, fog, mist or snow. The acidic substance flows through the ground, and makes its way into canals, mixing with sea water, damaging trees and other forms of life in the process. Dry deposition however, is when the wind blows acidic substances into drier regions. The acidic substances combine with dust or smoke to then fall to the earth as dry particles. The dry deposition of the acidic pollutants fall onto the ground, and other objects such as, cars and houses. |
CausesThere are a few causes to the occurrence of Acid Rain. Rotting vegetation and erupting volcanoes release chemicals that cause acid rain. Depending on the type of volcano, volcanoes can emit different types of acidic pollutants such as Sulphur dioxide, carbon dioxide and Nitrogen oxide. However, the major cause of acid rain is due to human activity in which the biggest factor is, the burning of fossil fuels. When human fossil fuels burn, SO2 and NOx are released into the atmosphere, reacting with water and oxygen to create another substance, which is a mild solution of sulphuric or Nitric acid. Other causes include, factories (smelting and refining) and vehicles, where they too, emit sulphur dioxide and Nitrogen Oxide pollutants. (nationalgeographic.com)
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