this gas in the world. When sulphur dioxide reaches the atmosphere, it oxidizes to first form a sulfate ion. 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. The following are the stoichiometric equations for the formation of sulphuric acid: S (in coal) + O2„_ SO2 2 SO2 + O2„_ 2 SO3 SO3„_ + H2O H2SO4 Nitric oxide and nitric dioxide are also components of acid rain. Its sources are mainly from power stations and exhaust fumes. Like sulfur dioxide, these nitrogen oxides rise into the atmosphere and are oxidized in clouds to form nitric acid. These reactions are also catalyzed in heavily polluted clouds where iron, manganese, ammonia and hydrogen peroxide are present. In Canada, the main sulfuric acid sources are non-ferrous smelters and power generation. On both sides of the border, cars and trucks are the main sources for nitric acid(about 40% of the total), while power generating plants and industrial commercial and residential fuel combustion together contribute most of the rest. In the air, the sulfur dioxide and nitrogen oxides can be transformed into sulfuric acid and nitric acid, and air current can send them thousands of kilometers from the source. When the acids fall to the earth in any form it will have large impact on the growth or the preservation of certain wildlife. NO DEFENSE One of the direct effects of acid rain is on lakes and its aquatic ecosystems. There are several routes through which acidic chemicals can enter the lakes. Some chemical substances exis...