The Dangers and Reality of Acid Rain
The Dangers and Reality of Acid Rain
Acidity is measured using a pH scale, with the number 7 being neutral. A substance with a pH value of less than 7 is acidic, while one of a value greater than 7 is basic. A substance with a pH of 6 is 10 times more acidic than another with a pH of 7. Usually the pH of 5.6 has been used as the baseline in identifying acid rain, although there has been much debate over the acceptance of this value. Interestingly enough, a pH of 5.6 is the pH value of carbon dioxide in equilibrium with distilled water. Hence, acid ran is defined as any rainfall that has an acidity level beyond what is expected in non-polluted rainfall. In essence, any precipitation that has a pH value of less than 5.6 is considered to be acid precipitation.
One of the main causes of acid rain is sulphur dioxide. Natural sources which emit this gas are volcanoes, sea spray , rotting vegetation and plankton. However, the burning of fossil fuels, such as coal and oil, are largely to be blamed for approximately half of the emissions of this gas in the world. When sulphur dioxide reaches the atmosphere, it oxidizes first . It then becomes sulphuric acid as it joins with hydrogen atoms in the air and falls back down to earth. Oxidation occurs the most in clouds and especially in heavily polluted air where other compounds such as ammonia and ozone help to catalyze the reaction, converting more sulphur dioxide to sulphuric acid. However, not all of the sulphur dioxide is converted to sulphuric acid. In fact, a substantial amount can float up into the atmosphere, move over to another area and return to earth unconverted. Nitric oxide and nitric dioxide are also components of acid rain. The sources of these components are mainly from power stations and exhaust fumes.
One of the most serious impacts of acid precipitation is on forests and soils. Great damage is done when sulphuric acid falls onto the earth as rain. Nutrients present in the soils are washed away. Aluminium also present in the soil is freed and this toxic element can be absorbed by the roots of trees. Thus, the trees are starved to death as they are deprived of their vital nutrients such as calcium and magnesium. Research has been made where...