heating, smelters, diesel engines and marine and rail transport, which creates sulfuric acid in rain. Nitrogen dioxide will also react with the rain, caused largely by transportation (cars, trucks, planes, etc.) and electric utilities, producing nitric acid. There is a certain degree of naturally occurring acidity in rain water. This acid is from reaction with alkaline chemicals, found in soils, lakes and stream, and can occasionally occur when a volcano erupts as well. Bacterial action in soils and degasing from oceanic plankton also contribute to the acidity found in rain. More than 90% of the sulfur and 95% of the nitrogen emissions which occur in North America are due to the pollution created by humans.1 How Is Acid Rain Formed? Acid rain consists mainly of acids formed in the atmosphere. It consists of the oxides of sulfur, SO2 and SO3, and of nitrogen NO and NO2. Let us examine the major contributor to acid rain, sulfur oxides. Natural sources which emit sulfur dioxide include volcanoes, sea spray, plankton and rotting vegetation. Despite these natural occurrences, the burning of fossil fuels (such as coal and oil) can be largely blamed for the emissions. The chemical reactions begin as energy from sunlight, in the form of photons, hit ozone molecules (O3) to form free oxygen (O2), as well as single reactive oxygen atoms (O). The oxygen atoms react with water molecules (H2O), producing electrically charged, negative hydroxyl radicals (HO). These hydroxyl radicals are responsible for oxidizing sulfur dioxide and nitrogen dioxide, which produces sulfuric acid and nitric acid. Some particles will settle to the ground (in the form of acid deposition) or vegetation can absorb some of the SO2 gas directly from the atmosphere. When sulfur dioxide comes in contact with the atmosphere, it oxidizes and forms a sulfate ion. It becomes sulfuric acid as it joins with hydrogen atoms in the air and falls down to earth. Oxidation occurs most in clouds, especially in heavily polluted air, where other compounds such as ammonia and ozone help to catalyze the reaction, increasing the amount of sulfur dioxide changing to sulfuric acid. Not all of the sulfur dioxide is converted to sulfuric acid, and it is not uncommon for a substantial amount to float up into the atmosphere, move to another area, and return to earth as sulfur dioxide, unconverted. S (in fossil fuels) + O2 =* SO2 2 SO2 + O2 =* 2 SO3 Much of the sulfur dioxide is converted to sulfur trioxide in the atmosphere SO3 + H2O =* H2SO4 The sulfur trioxide can then dissolve within water to form sulfuric acid Nitric oxide and nitric dioxide are mainly from power plants and exhaust fumes. Similar to sulfur dioxide, reactions are heavily catalyzed in heavily polluted clouds where iron, manganese, ammonia and hydrogen peroxide are present. Also, the formation of nitric acid can trigger further reactions which release new hydroxyl radicals to generate more sulfuric acid. The following is a typical reaction, which is direct combination of nitrogen and oxygen at the high temperature inside a car engine. N2 + O2 + heat =* 2NO 2NO + O2 =* 2NO2 This nitrogen monoxide immediately reacts with oxygen and forms nitrogen dioxide in the following reaction 3NO2 + H2O =* 2HNO3 (aq) + NO The nitrogen will then dissolve in water in the atmosphere and produce nitric acid There are several other potential contributors to acid rain. These include oxidation by products of alkene-ozone reactions, oxidation by reactions of NxOy species and oxidation by peroxy radicals. Each of these reactions, however prove to be minor contributors and are rather insignificant. How Is Acid Rain Harmful? Environmental Hazards Aquatic Ecosystems Acid rain has an effect on virtually all ecosystems it touches. Perhaps the most prominent, and equally as troubling is the harmful results it produces when in contact with lakes, streams and ponds. Scientists studying the effects of acid rain went to a lake about 135 km away from the On

Some topics in this essay:
SO2 SO3, Plant Life, Ontario- Manitoba, H+ H-, , Water Acid, Structures Scientists, Human Health, Air Force, Memorandum Intent, acid rain, sulfur dioxide, sulfuric acid, effects acid rain, effects acid, nitrogen dioxide, nitric acid, + o2, hydrogen ions, sulfur dioxide nitrogen, clams snails, drinking water, + o2 =*, dioxide sulfur dioxide, dioxide nitrogen dioxide,